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Texas pH Evaluation Project

Prepared by:

Texas Institute for Applied Environmental Research Tarleton State University

Stephenville, Texas

PR0810

November 2008

Texas pH Evaluation Project

Prepared for:

TMDL Program Texas Commission on Environmental Quality

Austin, Texas

Prepared by:

David Pendergrass Larry Hauck

Texas Institute for Applied Environmental Research Tarleton State University

Stephenville, Texas

PR0810

November 2008

Texas pH Evaluation Project Table of Contents

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TABLE OF CONTENTS

LIST OF FIGURES......................................................................................................... iii LIST OF TABLES .......................................................................................................... iv SECTION 1 INTRODUCTION......................................................................................1-1

1.1 Context................................................................................................................................ 1-1 1.2 Report Purpose and Organization....................................................................................... 1-1

SECTION 2 BACKGROUND .......................................................................................2-1

2.1 Water Quality and pH......................................................................................................... 2-1 2.2 Environmental Influences on Aquatic pH .......................................................................... 2-3

SECTION 3 DEFINITION OF STUDY AREAS AND METHODS OF DATA

ANALYSIS..............................................................................................................3-1 3.1 Definition of Study Areas................................................................................................... 3-1 3.2 Methods and Data Analysis................................................................................................ 3-2

SECTION 4 HISTORICAL DATA REVIEW OF IMPAIRED SEGMENTS AND

POTENTIAL SOURCES OF pH IMPAIRMENT......................................................4-1 4.1 Segment 0105—Rita Blanca Lake ..................................................................................... 4-1

4.1.1 Historical Data Review ................................................................................................ 4-1 4.1.2 Potential Sources of pH Impairment and Recommendations....................................... 4-3

4.2 Segment 0229—Upper Prairie Dog Town Fork Red River ............................................... 4-5

4.2.1 Historical Data Review ................................................................................................ 4-5 4.2.2 Potential Sources of pH Impairment and Recommendations....................................... 4-5

4.3 Segment 0401—Caddo Lake.............................................................................................. 4-9

4.3.1 Historical Data Review ................................................................................................ 4-9


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4.3.2 Potential Sources of pH Impairment and Recommendations..................................... 4-12 4.4 Segment 0402—Big Cypress Creek below Lake O’ the Pines ........................................ 4-13

4.4.1 Historical Data Review .............................................................................................. 4-13 4.4.2 Potential Sources of pH Impairment and Recommendations..................................... 4-13

4.5 Segment 0507—Lake Tawakoni ...................................................................................... 4-15


4.6 Segment 0605—Lake Palestine........................................................................................ 4-19


4.7 Segment 0606—Neches River above Lake Palestine....................................................... 4-23


4.8 Segment 0803—Lake Livingston..................................................................................... 4-25


4.9 Segment 0818—Cedar Creek Reservoir........................................................................... 4-30


4.10 Segment 1212—Lake Somerville................................................................................... 4-36

4.10.1 Historical Data Review ............................................................................................ 4-37 4.10.2 Potential Sources of pH Impairment and Recommendations................................... 4-37

SECTION 5 SUMMARY OF FACTORS CONTRIBUTING TO pH EXCURSIONS IN

LISTED TEXAS WATER BODIES AND RECOMMENDED ACTIONS..................5-1


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SECTION 6 REFERENCES.........................................................................................6-1 APPENDIX A CORRELATIONS OF SELECTED ANALYTES FROM IMPAIRED

SEGMENTS........................................................................................................... A-1

LIST OF FIGURES

Figure 2-1 National rainfall pH trends................................................................................... 2-5 Figure 2-2 Average annual precipitation in Texas 1971 – 2000 ........................................... 2-5 Figure 3-1 Map of Texas showing distribution of the eight reservoirs and two streams

considered in this study........................................................................................ 3-3 Figure 4-1 Map of Rita Blanca Lake (Segment 0105) .......................................................... 4-2 Figure 4-2 Satellite image of Rita Blanca Lake, Hartley County, Texas .............................. 4-3 Figure 4-3 Time history of pH for impaired AUs of Rita Blanca Lake, Segment 0105

(data for 1998 – 2006).......................................................................................... 4-4 Figure 4-4 Map of Upper Prairie Dog Town Fork Red River (Segment 0229) .................... 4-6 Figure 4-5 Time history of pH for impaired AUs of Upper Prairie Dog Town Fork Red

River, Segment 0229 (data for 2003 – 2006)....................................................... 4-7 Figure 4-6 Satellite image of Lake Tanglewood dam and Station 18317 of Segment

0229, Randall County, Texas............................................................................... 4-8 Figure 4-7 Map of Caddo Lake and Big Cypress Creek below Lake of the Pines

(Segments 0401 and 0402)................................................................................. 4-10 Figure 4-8 Time history of pH for impaired AUs of Caddo Lake, Segment 0401

(data for 1994 – 2006)........................................................................................ 4-11 Figure 4-9 Time history of pH for impaired AUs of Big Cypress Creek below Lake O’

the Pines, Segment 0401(data for 1994 – 2006) ................................................ 4-14 Figure 4-10 Map of Lake Tawakoni (Segment 0507) ........................................................... 4-16 Figure 4-11 Time history of pH for impaired AUs of Lake Tawakoni, Segment 0507

(data for 1999 – 2006)........................................................................................ 4-18


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Figure 4-12 Map of Lake Palestine (Segment 0605) and Neches River above Lake Palestine (Segment 0606) .................................................................................. 4-20

Figure 4-13 Seasonality of pH in Lake Palestine, assessment units 3, 9, and 10

combined............................................................................................................ 4-21 Figure 4-14 Time history of pH for impaired AUs of Lake Palestine, Segment 0605

(data for 1999 – 2006)........................................................................................ 4-22 Figure 4-15 Time history of pH for impaired AUs of Neches River above Lake Palestine,

Segment 0606(data for 1995 – 2006)................................................................. 4-24 Figure 4-16 Map of Lake Livingston (Segment 0803).......................................................... 4-27 Figure 4-17 Time history of pH for impaired AUs of Lake Livingston, Segment 0803

(data for 1999 – 2006)........................................................................................ 4-28 Figure 4-18 Seasonality of pH in Lake Livingston, assessment units 1 and 6 combined ..... 4-29 Figure 4-19 Map of Cedar Creek Reservoir (Segment 0818)................................................ 4-31 Figure 4-20 Cedar Creek Reservoir chlorophyll-a 17-yr trend (CCWP 2008) ..................... 4-32 Figure 4-21 Time history of pH for Cedar Creek Reservoir, Segment 0803(data for 1997 –

2006) .................................................................................................................. 4-33 Figure 4-22 Cedar Creek Reservoir pH and trend lines for excursions (red) and entire

dataset (black) .................................................................................................... 4-34 Figure 4-23 Time history for pH of impaired AUs of Lake Somerville, Segment 1212

(data for 1997 – 2006)........................................................................................ 4-38 Figure 4-24 Map of Lake Somerville (Segment 1212).......................................................... 4-39

LIST OF TABLES

Table 2-1 Ionic gradients in reservoirs across Texas selected from Ground and Groeger (1994)................................................................................................................... 2-2

Table 3-1 Segment names, impaired assessment units (AU), pH criteria, year first listed

for pH, and designated uses ................................................................................. 3-4 Table 3-2 Ecoregion descriptions for impaired segments derived from Griffith et al. (2004)

.............................................................................................................................. 3-5


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Table 3-3 Screening levels for nutrients and CHLA in Texas freshwater streams and reservoirs (TCEQ 2008a)..................................................................................... 3-5

Table 3-4 Summary of pH, alkalinity, DO, and specific conductance for each impaired

assessment unit. ND indicates no data................................................................ 3-6 Table 4-1 Watershed pollutant loadings (% contribution) per land use, adapted from

CCWP (2008)..................................................................................................... 4-35 Table 5-1 Summary of Recommendations for pH Impaired Segments Included in the

Study .................................................................................................................... 5-2


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List of Acronyms

ALCOA Aluminum Company of AmericaASCE American Society of Civil EngineersAU Assessment UnitBIC Berner International CorpCCWP Cedar Creek Watershed PartnershipCWA Clean Water ActFWSD Freshwater Supply DistrictMGD Million Gallons per DayMUD Municipal Utiility DistrictNADP National Atmospheric Deposition ProgramNOAA National Oceanic and Atmospheric AdministrationNETMWD Northeast Texas Municipal Water DistrictOSSF On-Site Sewage FacilityRRA Red River AuthoritySRA Sabine River AuthorityS.U. Standard UnitsSWQMIS Surface Water Quality Monitoring Information SystemTRWD Tarrant Regional Water DistrictTAMU Texas A&M UniversityTAMU-SCL Texas A&M University-Soil Characterization LaboratoryTCEQ Texas Commission on Environmental QualityTIAER Texas Institute for Applied Environmental ResearchTNRCC Texas Natural Resource Conservation ComissionTWDB Texas Water Development BoardTMDL Total Maximum Daily LoadTRA Trinity River AuthorityTSI Trophic State IndexUSACE U.S. Army Corp of EngineersUSEPA U.S. Environmental Protection AgencyWWTF Wastewater Treatment FacilityWMA Wildlife Management Area


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List of Chemical and Analyte Abbreviations

Alk AlkalinityCa CalciumCaCO3 Calcium carbonateCHLA Chlorophyll-aCO2 Carbon dioxideCO3

2- CarbonateDO Dissolved oxygenDO%sat Dissolved oxygen percent saturationEndTime End time of water sampleFeS2 Pyrite

H+ Hydrogen ionH2CO3 Carbonic acidH2SO4 Sulfuric acid

HCO3- Bicarbonate

Na SodiumNaHCO3 Sodium bicarbonateNH3-N Ammonia-nitrogenNO3-N Nitrate-nitrogenOH- Hydroxl ionOP OrthophosphorusSecchi Secchi depthSpCond Specific conductanceTP Total phosphorus

Texas pH Evaluation Project Introduction

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SECTION 1

INTRODUCTION 1.1 Context

Section 303(d) of the Clean Water Act (CWA) and U.S. Environmental Protection Agency (USEPA) Water Quality Planning and Management Regulations (40 Code of Federal Regulations [CFR] Part 130) require states to develop total maximum daily loads (TMDL) for water bodies not meeting designated uses where water quality-based controls are in place. TMDLs establish the allowable loadings of pollutants or other quantifiable parameters for a water body based on the relationship between pollution sources and in-stream water quality conditions, so states can implement water quality-based controls to reduce pollution from both point and nonpoint sources and restore and maintain the quality of its water resources (USEPA 1991).

As specified in the states’ water quality assessment guidance (e.g., TCEQ 2008a), all

water bodies are assigned to one of five categories ranging from Category 1 (attaining all water quality standards and no use is threatened) to Category 5 (water body does not meet applicable water quality standards or is threatened for one or more designated uses by one or more pollutants). By definition all water bodies on the State of Texas 303(d) list are Category 5 and are further assigned to one of three subcategories: Category 5a (a TMDL is underway, scheduled, or will be scheduled), Category 5b (a review of the water quality standards for the water body will be conducted before a TMDL is scheduled), or Category 5c (additional data and information will be collected before a TMDL is scheduled).

The State of Texas 2008 303(d) list (TCEQ 2008b) includes numerous water bodies

reported as having pH exceedances, either above or below applicable pH criteria. Texas Surface Water Quality Standards require a majority of water bodies to maintain a pH range of 6.5-9.0 with a few exceptions (TNRCC 2000a). Most of the water bodies listed for pH have been assigned to either Category 5b or Category 5c. 1.2 Report Purpose and Organization

The TCEQ is leading an effort to assess the water quality of several classified segments in Texas reported on the State of Texas 303(d) list for pH impairments. These classified segments include: • Rita Blanca Lake, Segment 0105, Category 5c, first listed in 2004 • Upper Prairie Dog Town Fork Red River, Segment 0229, Category 5c, first listed in

2006 • Caddo Lake, Segment 0401, Category 5c, first listed in 1996 • Big Cypress Creek below Lake of the Pines, Segment 0402, Category 5b, first listed in

2000 • Lake Tawakoni, Segment 0507, Category 5c, first listed in 2008 • Lake Palestine, Segment 0605, Category 5c, first listed in 2006 • Neches River above Lake Palestine, Segment 0606, Category 5c, first listed in 2002

Texas pH Evaluation Project Introduction

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• Lake Livingston, Segment 0803, Category 5c, first listed in 2008 • Cedar Creek Reservoir, Segment 0818, Category 5c, first listed in 2002 • Lake Somerville, Segment 1212, Category 5c, first listed in 2002 With the exception of Segment 0402, each of these segments is in Category 5c - additional data and information will be collected before a TMDL is scheduled. The numeric pH criteria will be addressed on Segment 0402 during the next standards revision.

TCEQ TMDL Program contracted with the Texas Institute for Applied Environmental Research (TIAER) to (1) acquire historical data and review information necessary to assess segment listings, (2) evaluate water quality using graphical and statistical methods, and (3) assist the TCEQ in preparing the justification for further study, listing category changes, standards adjustments, delisting, or developing TMDLs. This report is the culmination of a 3-month effort from June through August 2008 to obtain and analyze data on 10 TCEQ classified segments included in the State of Texas 2008 303(d) list for pH impairments. The report begins with a brief background section on basic pH principles followed by descriptions of the location of the designated segments and data analysis methods. These two sections are followed by analysis of each segment including environmental context, major point and nonpoint sources of nutrient enrichment, historical sampling data, listing information, and suggestions for future study. The report closes with a summary of findings and general trends in pH exceedances across the segments.

Texas pH Evaluation Project Background

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SECTION 2

BACKGROUND 2.1 Water Quality and pH

In the simplest terms, pH is a measure of hydrogen ion concentration: pH = - log10 [H+] (Eq. 1)

where [H+] is the hydrogen ion concentration in moles/liter. More specifically, it is a measure of the relative concentrations of hydrogen (H+) and hydroxyl (OH-) ions and is measured on a log scale ranging from 1-14, acidic (low) to basic (high). The unit of measurement of pH is standard units (S.U.), but common practice, as will be employed in this report, is to leave off the units when reporting numeric pH values. In pure water, both ions are in dynamic equilibrium and the pH is 7 (neutral). When H+ ions increase and OH- ions correspondingly decrease, water becomes more acidic and because of the negative logarithmic scale pH values become less than 7. Alternatively, if OH- is in greater abundance than H+, the water is more basic (i.e., pH > 7). Most aquatic organisms can tolerate a pH range of 6.0 ─ 9.0 but suffer significant reproductive and developmental problems, and eventually death, if the water they inhabit becomes too acidic or basic.

Hydrogen ion concentration in water is directly proportional to aqueous carbon dioxide

(CO2) and inversely proportional to carbonate (CO32-) (Boyd 1990). When CO2 is removed from

a system at equilibrium, carbonate increases then hydrolyzes in the presence of water releasing a bicarbonate ion and OH- (Eq. 2). This results in more basic water.

CO3

2- + H2O ↔ HCO3- + OH- (Eq. 2)

When CO2 is increased, it joins with water to create carbonic acid (H2CO3) which

dissociates to release bicarbonate (HCO3-) and a hydrogen ion (H+) (Eq. 3). This makes water

more acidic. CO2 + H2O ↔ H2CO3 ↔ HCO3

- + H+ (Eq. 3) Aqueous CO2 is in dynamic equilibrium with atmospheric CO2. This component can be added to a summary of Equations 2 and 3:

CO2 (air) ↔ CO2 (dissolved) + H2O ↔ H2CO3 ↔ H+ + HCO3

- ↔ H+ + CO32- (Eq. 4)

Photosynthesis and respiration tend to govern the amount of CO2 in water. However, where bicarbonate is abundant, water is usually resistant to changes in pH caused by biochemical processes. Wetzel (2001) explains it this way:

An addition of hydrogen ions neutralizes hydroxyl ions formed by the dissociation of HCO3

- and CO32- but more hydroxyl ions are formed


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immediately by reaction of the carbonate with water. Consequently, the pH remains essentially unaltered, unless the supply of carbonate or bicarbonate ions is exhausted. Similarly, when hydroxyl ions are added they react with bicarbonate ion: HCO3

- + OH- ↔ CO32- + H2O.

Alkalinity generally refers to the amount of carbonate or bicarbonate in water. As demonstrated above, alkaline water tends to be basic and buffered from pH swings because of reactions with carbonate and bicarbonate. Thus alkalinity has often been used synonymously with buffering capacity, “basicness” of water, and even hardness [commonly measured as mg/L of calcium carbonate (CaCO3)], because in natural waters carbonate is often bound with calcium. In fact, all references to alkalinity in this study are in units of “mg/L as CaCO3”. Where calcium (Ca) and sodium (Na) are abundant in the soil, carbonate and bicarbonate can be stored as CaCO3 and sodium bicarbonate (NaHCO3). In productive alkaline waters where pH is consistently above 8.3, inorganic carbon in the form of dissolved CO2 is rare (CO3

2- becomes the dominant species of inorganic carbon) and algae and phytoplankton assimilate carbon from alternative sources such as CaCO3 and NaHCO3. As carbonate is hydrolyzed it releases OH- resulting in even higher pH (Eq. 2). Thus, the Texas Panhandle, which has soils high in calcium and sodium content (Table 2-1), can be very basic during warm summer afternoons when photosynthetic assimilation of inorganic carbon is at a maximum. Boyd (1990) noted that in some eutrophic waters with high levels of sodium and potassium pH can soar to 10 – 12 as photosynthesis uses up CO2 and equilibrium reactions cause the sodium and potassium carbonate compounds to dissociate. Table 2-1 Ionic gradients in reservoirs across Texas selected from Ground and Groeger

(1994). Values represent mean values from the individual reservoirs. Sample n = 15, 44, and 21 for West, Central and East populations, respectively.

Variable West Central East

Median 8.2 8.2 7.4 pH Range 7.9 – 8.5 7.9 – 8.4 6.6 – 7.9 Mean 129 134 39 Total Alkalinity

(mg CaCO3 L-1) Range 69 – 180 93 – 206 15 – 76 Mean 2444 533 178 Specific

Conductance (μS cm -1)

Range 1138 – 5932 287 – 983 89 – 274

Mean 144 49 14 Calcium (mg L-1) Range 56 – 759 24 – 76 6.5 – 26

Mean 436 41 15 Sodium (mg L-1) Range 48 – 2711 6 – 128 6.7 – 39

In regions where alkalinity is low, such as East Texas (Table 2-1), buffering capacity is

generally low as well, and large diel swings in dissolved CO2 caused by photosynthesis-respiration cycles can result in large changes in pH during warmer periods. Some natural waters contain virtually no carbonate and their alkalinity is effectively zero. During peak respiration the


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pH in these water bodies can reach as low as 4.5. Dips below 4.5 have been recorded in the Neches River above Lake Palestine (Crowe 2008) but as Boyd (1990) notes, such pH depressions are attributable to other mineral acids in the soil, such as sulfuric acid (H2SO4), and not the absence of alkalinity. 2.2 Environmental Influences on Aquatic pH

In reservoirs, eutrophication (high levels of primary production) is typically the dominant driving force behind pH fluctuations. During summer months when aquatic macrophyte and phytoplankton production is high, aqueous inorganic carbon (i.e. dissolved CO2) is removed through photosynthesis and pH rises. This process is especially apparent in deep, open water where phytoplankton are the dominant primary producers. In contrast, sunlight penetration of the water column is limited in fluvial and transition zones by turbidity, shading, and heavy detritus loads, reducing rates of CO2 removal by photosynthesis. In addition, microbial decomposition of the detritus in these zones can cause the rate of respiration to exceed the rate of production creating an excess of CO2 and lowering pH. Diel fluctuations in pH also occur in response to daily peaks and valleys in photosynthetic activity. In a eutrophic reservoir, summer diel peaks are expected to be higher than winter peaks because of seasonal differences in gross productivity. Although climate and hydrogeology have a significant influence on pH, in general, if the gross primary production to community respiration ratio (p:r) is high, pH will increase (resulting from a net decrease in CO2). If the ratio is small, pH will decrease (resulting from a net increase in CO2).

Recent research indicates that reservoir eutrophication is primarily an anthropogenic

phenomenon (Smith et al. 2006). In Texas, anthropogenic nutrient inputs to rivers and reservoirs “dwarf” natural sources according to Ground and Groeger (1994) who also postulated that nearly all surface waters in the state have been impacted by anthropogenic nutrient loading. The portion of eutrophication of Texas reservoirs attributable to human development (point and nonpoint sources), hereafter called cultural eutrophication (sensu Dodds 2006), is of special significance because it is an unnatural process yet has potential to be reasonably controlled with improved understanding of its underlying mechanisms. Point source discharges, such as wastewater treatment facilities (WWTFs), can indirectly alter pH in streams and reservoirs through nutrient enrichment causing high algal productivity. Nonpoint nutrient contributions from agriculture are of primary concern in many watersheds with nutrient enriched reservoirs because agricultural contributions often outpace point source contributions by a large margin (e.g., McFarland and Hauck 1999 and CCWP 2008). Exceptions to this rule of nonpoint source dominance apply where the reservoir is relatively small and the primary inflow is from point sources, such as in Rita Blanca Reservoir in the Texas Panhandle which is largely fed by the City of Dalhart WWTF (see Section 4.1).

Land use can exert influence on pH within the climatic, geological, and vegetative

context of the region. Impermeable cover in urban areas limits percolation by rainwater and its interaction with minerals found in soils and bedrock. Mine trailings in the form of pyrite (FeS2), abundant in east Texas, can increase the H2SO4 content of soil as FeS2 is oxidized; a process known to depress soil pH for a century after mining operations have ceased (Skousen 1990, Cole


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1994). Riverine segments are most susceptible to the effects of acidic groundwater discharge, especially during seasons when groundwater dominates stream inflows (Dodds 2002).

In streams, vegetative cover can affect pH on a seasonal basis, especially where

deciduous trees are abundant. For example, Crowe (2008) found that in the Neches River a large drop in stream pH in late fall from 6.6 to 4.8 coincided with sap-drop in the local forest. When trees go dormant during the winter, they draw less moisture from the soil and groundwater flows more freely, a phenomenon commonly signaled in temperate areas by an increase in stream discharge. As groundwater flows more freely through the sulfur-bearing soils typical of east Texas, it forms a dilute sulfuric acid before entering surface flows. Additional leaf fall during the fall and winter increases the coarse particulate matter loads which further increases the dissolved CO2 respired by microbes decomposing the leaf litter. These gains in CO2 contribute to lower surface-water pH (see Eq. 3).

In streams and reservoirs, the severity and direction (acid or basic) of pH fluctuations are

partly functions of regional geology. West and central Texas limestone geology contains relatively higher amounts of CO3

2- than east Texas, primarily in the form of calcium carbonate. Far-east Texas (ecoregion 35, Level III; Griffith et al. 2004) is characterized by acidic sandy-loamy soils. This geological difference alone accounts for much of the range of values in several ionic categories in Texas reservoirs (Ground and Groeger 1994; Table 2-1).

At the continental scale, climate exerts influence on local pH ranges. Rain is naturally

moderately acidic (pH ~ 5.6) because it interacts with atmospheric CO2 and airborne particles during descent. Upon landing, rain weathers soil and bedrock (to varying degrees) through physical and chemical action. Dissolved soil components flow with surface runoff and groundwater and can cause mild to drastic pH fluctuations in surface-water bodies, particularly streams. Across the continental United States, rainfall pH decreases west to east and this pattern applies to the large state of Texas that spans approximately 13 degrees of longitude: west Texas precipitation is consistently above 5.3 while eastern portions regularly receive rain with a pH under 4.8 (NADP 2008; Figure 2-1). Challenged to address the possible influences of acid rain on water quality in East Texas, TCEQ commissioned a report published in 2007 (Crowe et al. 2007) that found no classic signals of unnaturally acidic rainfall and thus dismissed anthropogenic causes as a regional concern. How much precipitation falls is also important to the mineral weathering processes that impact the pH of runoff and groundwater. Two segments in this study, Rita Blanca Lake and Upper Prairie Dog Town Fork Red River, are in the Panhandle where average precipitation totals 18 inches – 22 inches (457 mm – 559 mm) (TWDB 2007; Figure 2-2). In contrast, the other eight segments in this report are in regions of east Texas that receive 42 inches – 50 inches (1,067 mm – 1,270 mm) of precipitation per year.


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Figure 2-1 National rainfall pH trends (Source: NADP 2008).

Figure 2-2 Average annual precipitation in Texas 1971 – 2000 (Source: TWDB 2007).


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Texas pH Evaluation Project Definition of Study Areas and Methods of Data Analysis

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SECTION 3

DEFINITION OF STUDY AREAS AND METHODS OF DATA ANALYSIS

3.1 Definition of Study Areas

For the impaired water bodies included in this study, the following segment and assessment unit (AU) descriptions are from TCEQ (2008b). Segments are designated in the water quality standards and AUs are units created to facilitate sub-segment characterization.

Rita Blanca Lake (Segment 0105): From Rita Blanca dam up to normal pool level of 1176.5

m (impounds Rita Blanca creek). Segment 0105 contains only one AU. Upper Prairie Dog Town Fork Red River (Segment 0229): From a point 100 meters

upstream of the confluence of Salt Fork Creek in Armstrong County to Lake Tanglewood Dam in Randall County.

• AU 02—Palo Duro Canyon State Park upstream boundary to upper end of segment at Tanglewood Dam.

Caddo Lake (Segment 0401): From the Louisiana State Line in Harrison/Marion County to

a point 12.3 km downstream of SH 43 in Harrison/Marion County, up to pool elevation of 51.4 m (impounds Big Cypress Creek).

• AU 02—Harrison Bayou arm • AU 03—Goose Prairie arm • AU 05—Clinton Lake

Big Cypress Creek Below Lake O’ the Pines (Segment 0402): From a point 12.3 km

downstream of SH 43 in Harrison Marion County to Ferrell’s Bridge Dam in Marion County.

• AU 01—Lower 14.5 km • AU 02—17.7 km below Black Cypress Creek

Lake Tawakoni (Segment 0507): From Iron Bridge Dam in Rains County up to normal

pool elevation of 133.2 m (impounds Sabine River). • AU 04—Cowleech Fork of Sabine River arm

Lake Palestine (Segment 0605): From Blackburn Crossing Dam in Anderson/Cherokee

County to a point 6.7 km downstream of FM 279 in Henderson/Smith County, up to normal pool elevation of 105.2 m (impounds Neches River).

• AU 03—Mid-lake near Tyler PWS intake • AU 09—Flat Creek arm • AU 10—Upper Lake

Neches River above Lake Palestine (Segment 0606): From a point 6.7 km downstream of

FM 279 in Henderson/Smith County to Rhines Lake Dam in Van Zandt County. • AU 02—Prairie Creek to river km 11.3


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• AU 03—River km 11.3 to headwaters

Lake Livingston (Segment 0803): From Livingston Dam in Polk/San Jacinto County to a point 1.8 km upstream of Boggy Creek in Houston/Leon County, up to normal pool elevation of 39.9 m (impounds Trinity River).

• AU 01—Lowermost portion of reservoir, adjacent to dam • AU 06—Middle portion of reservoir centering on US 190

Cedar Creek Reservoir (Segment 0818): From Joe B. Hoggsett Dam in Henderson County

up to normal pool elevation of 98.1 m (impounds Cedar Creek). • AU 01—From dam to just above Clear Creek cove entrance • AU 02—Caney Creek cove • AU 03—Clear Creek cove • AU 04—Lower portion of reservoir east of Key Ranch Estates • AU 05—Cove off lower portion of reservoir adjacent to Clearview Estates • AU 06—Middle portion of reservoir downstream of Twin Creeks cove • AU 07—Twin Creeks cove • AU 08—Prairie Creek cove • AU 09—Upper portion of reservoir adjacent to Lacy Fork cove • AU 11—Upper portion of reservoir east of Tolosa • AU 12—Uppermost portion of reservoir downstream of Kings Creek

Somerville Lake (Segment 1212): From Somerville Dam in Burleson/Washington County

up to normal pool elevation of 72.5 m (impounds Yegua Creek). • AU 01—Eastern end of reservoir near dam • AU 03—Middle of reservoir near Birch Creek State Park

See Figure 3-1 for a state map showing all segments not meeting the criteria for pH and Table 3-1 for a summary of designated uses and pH criteria for each segment and its impaired assessment units. These 10 segments are concentrated in the eastern quarter of the state, with the exception of Segments 0105 and 0229 in the Panhandle. Altogether the segments span three Level-III and five Level-IV ecoregions (Griffith et al. 2004). Table 3-2 briefly summarizes ecoregion descriptions and the segments they contain.

Texas water bodies are listed for concern if any of their nutrient or chlorophyll-a (CHLA)

samples exceed screening levels more than 20 percent of the time. Screening levels have been established as the 85th percentile values for each analyte in freshwater streams and reservoirs and they are provided in Table 3-3. These screening levels were used to assess the potential impact of cultural eutrophication through nutrient loading, a cause of pH exceedances in some segments.

3.2 Methods and Data Analysis

At the start of this investigation the TCEQ provided TIAER a nearly complete body of

surface water sample data for all of the 10 impaired segments in this study. These data were taken from TCEQ’s SWQMIS database. This data set included many samples that did not meet the requirements for inclusion in the 305(b) assessment, the section of the CWA that requires biennial state water quality assessment reporting and from which the 303(d) list is developed. A


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Figure 3-1 Map of Texas showing distribution of the eight reservoirs and two streams considered in this study.


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Table 3-1 Segment names, impaired assessment units (AU), pH criteria, year first listed for pH, and designated uses. Uses are according to Texas Surface Water Quality Standards (TNRCC 2000a).

Segment AU pH Criteria First

Listed Designated

Uses Low High

Rita Blanca Lake 0105_01 6.5 9.0 2004 NCR, L, WF Upper Prairie Dog Town

Fork Red River 0229_02 6.5 9.0 2006 CR, H

Caddo Lake 0401_02 6.0 8.5 0401_03 6.0 8.5 0401_05 6.0 8.5

1996

CR, H, PS

Big Cypress Creek below Lake of the Pines

0402_01 0402_02 6.0 8.5 2000 CR, H, PS

Lake Tawakoni 0507_04 6.0 9.0 2008 CR, H, PS Neches River above Lake

Palestine 0606_02 0606_03 6.0 8.5 2002

2004 CR, I, PS

Lake Palestine 0605_03 6.0 8.5 0605_09 6.0 8.5 0605_10 6.0 8.5

2006

CR, H, PS

Neches River above Lake Palestine

0606_02 0606_03 6.0 8.5 2002 CR, I, PS

Lake Livingston 0803_01 6.5 9.0 0803_06 6.5 9.0 2008 CR, H, PS

Cedar Creek Reservoir 0818_01 6.0 8.5 0818_02 6.0 8.5 0818_03 6.0 8.5 0818_04 6.0 8.5 0818_05 6.0 8.5 0818_06 6.0 8.5 0818_07 6.0 8.5 0818_08 6.0 8.5 0818_09 6.0 8.5 0818_11 6.0 8.5 0818_12 6.0 8.5

2002

CR, H, PS

Lake Somerville 1212_01 6.0 8.5 1212_03 6.0 8.5 2002 CR, H, PS

CR = contact recreation; NCR = non-contact recreation; H = high aquatic life use; I = intermediate aquatic life use; L = limited aquatic life use; WF = waterfowl habitat; PS = public water supply


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Table 3-2 Ecoregion descriptions for impaired segments derived from Griffith et al. (2004).

Ecoregion Level Segment III IV Level IV Brief Description

0105 25 25e High, dry, flat, large % is cropland, some grazeland, high oil/gas production, Ustic soil

0229 26 26c Badlands with little cropland, some grazeland, riparian vegetation includes cottonwood, willow, hackberry, highly saline Ustic soil

0507 33 33a 0818 33 33a

Post-oak savanna though most land is now pasture and range, Udic acid sandy to clayey loams in low-lying areas, many areas with dense underlying clay pan

1212 33 33b Hardwood forests with much pasture and range, irregular topography, Ustic sandy to sandy-loam soil

0401 35 35a 0402 35 35a 0605 35 35a 0606 35 35a

Mostly well drained sandy-loamy Ultisols and Alfisols, mix of hardwoods, loblolly pine, and grasses, gentle rolling slopes, some grazing pasture, lumber, oil/gas production

0803 35 35e Mostly longleaf pine forest on hilly, dissected topography, acidic sandy-loamy soil

Table 3-3 Screening levels for nutrients and CHLA in Texas freshwater streams and

reservoirs (TCEQ 2008a).

concerted effort was made to analyze the same body of data TCEQ used in its 305(b) assessments. For segments first listed in 2008 (0507 and 0803) TIAER analyzed samples from 1999 – 2006 per TCEQ guidance (TCEQ 2008a). Because some segments were first listed in 1996, 2000, 2002, 2004, or 2006, TIAER used additional data collected prior to 1999 that TCEQ used in their initial listings of these segments. A comparison of TIAER’s culled dataset to TCEQ’s dataset revealed near perfect matches to the number of samples assessed and the rate of exceedances. A summary of pH, alkalinity, dissolved oxygen (DO), and specific conductance data by segment and impaired assessment unit are provided in Table 3-4, which provides a general characterization of several water quality constituents associated with pH.

Freshwater Stream Reservoir

Ammonia NH3-N (mg/L) 0.33 0.11Nitrate NO3-N (mg/L) 1.95 0.37Orthophosphate OP (mg/L) 0.37 0.05Total Phosphorus TP (mg/L) 0.69 0.20Chlorophyll-a CHLA (μg/L) 14.10 26.70


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Table 3-4 Summary of pH, alkalinity, DO, and specific conductance for each impaired assessment unit. ND indicates no data.

Seasonality of median pH for each segment was calculated with ANOVA for segments

that qualified for parametric analysis, i.e., segments with normally distributed data. For segments with data that was not normally distributed (Segments 0507, 0606, 0818, 1212), overall seasonality was determined with a Kruskal-Wallis test, and Wilcoxon two-sample z-tests were used for between-season comparisons. Pearson correlation coefficients were determined by using the means of combined data for selected analytes from each segment. Correlation matrices are presented in Appendix A. Dissolved oxygen percent saturation (DO%sat), an indicator of primary productivity, was not available in the dataset acquired from TCEQ. To allow calculation

Segment AU nMedian Range Mean Range Mean Range Mean Range

RitBla 0105_01 18 9.4 7.9-10.5 312 208-443 11.4 4.9-20.0 1266 946-2029PraDog 0229_02 13 9.2 8.2-10.1 222 156-375 8.4 5.3-11.5 1769 1280-2350Caddo 0401_02 88 6.4 5.3-7.9 23 7-47 4.1 0.3-12.1 162 70-347

0401_03 8 6.2 4.9-7.9 16 5-47 3.6 0.2-12.1 120 73-3470401_05 86 6.3 5.5-7.3 13 6-26 4.4 0.1-11.0 115 68-160

BigCyp 0402_01 72 6.4 5.5-8.1 14 6-23 7.3 3.7-13.4 112 53-1610402_02 76 6.5 5.4-7.6 15 7-29 7.3 1.8-12.7 121 64-325

Tawako 0507_04 144 8.4 7.1-9.3 68 36-94 9.3 5.3-12.7 170 80-225Palest 0605_03 38 7.5 6.8-9.4 33 20-50 8.5 3.6-13.2 213 128-307

0605_09 19 8.3 7.3-9.2 41 27-52 8.5 5.3-13.7 249 203-3010605_10 10 8.2 7.3-8.9 45 22-62 8.1 4.6-10.3 293 256-353

NecPal 0606_02 38 6.7 3.5-7.0 42 5-114 4.2 0.4-9.7 332 80-18400606_03 17 6.7 5.4-7.7 33 5-69 5.0 0.2-8.1 304 130-622

Living 0803_01 104 8.2 6.7-9.9 89 59-144 9.8 3.6-16.1 346 264-3970803_06 43 8.6 7.2-9.6 95 43-116 9.6 1.9-23.0 432 368-539

CedCrk 0818_01 60 7.9 6.6-9.4 54 40-72 8.2 2.1-14.1 191 124-2700818_02 17 8.3 7.4-9.1 ND ND 8.5 4.1-16.1 166 128-1900818_03 17 8.4 7.4-9.7 ND ND 8.8 4.0-15.5 167 127-1920818_04 49 8.0 7.3-9.4 55 44-73 8.1 4.1-11.8 191 125-2730818_05 18 8.6 7.5-9.6 ND ND 9.4 5.9-16.0 168 125-2060818_06 157 8.0 6.5-9.4 56 42-101 8.1 1.9-15.2 197 123-3540818_07 15 8.6 7.6-9.3 ND ND 8.5 5.5-13.6 171 128-1920818_08 46 8.6 7.2-9.3 50 36-59 8.4 4.9-11.1 187 130-2450818_09 49 8.1 7.2-9.7 54 36-80 8.3 3.5-12.3 199 95-2870818_11 43 8.3 7.3-11.6 56 41-77 8.2 5.0-12.5 212 129-3270818_12 16 8.1 7.2-9.8 ND ND 9.1 4.8-13.0 600 138-1322

Somerv 1212_01 81 8.2 5.4-9.3 62 41-72 8.4 2.8-13.6 398 232-5711212_03 36 8.6 7.8-9.6 60 44-72 9.5 5.8-13.0 405 264-550

Sp. Cond.(μmhos/cm)pH

Alkalinity (mg/L as CaCO3)

DO(mg/L)


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of DO%sat, an equation from the American Society of Civil Engineers (ASCE 1960) was used to approximate DOsat using water temperature (T; °C):

DOsat =14.652 - 0.41022T + 0.007991T2 - 0.000077774T3 Eq. 5

Correlations between DO%sat and pH were determined with Pearson correlation coefficient analysis. As a matter of convention, all statements of statistical significance are based on α = 0.05. The term “impaired” is used in the context of stations, assessment units, and segments, and in all cases refers to failure to meet designated uses. Precipitation information was taken primarily from NOAA (2002). In a few cases, precipitation means are provided instead of medians indicating they originated from local weather stations closer to the segment under discussion. Historical stream discharge and reservoir storage data was taken from USGS gage data. Population numbers are based on the 2000 U.S. Census (U.S. Census Bureau 2008). There are several references to TCEQ’s Trophic State Index (TSI) ranks of reservoirs (TCEQ 2008c). The rankings were determined by Carlson’s Trophic State Index for chlorophyll-a (CHLA) and reservoirs are ranked relative to one another out of a total of 102 for which data were available. As examples, among the study reservoirs, Caddo Lake, ranked 53rd, is considered moderately eutrophic for CHLA whereas Rita Blanca Lake, ranked 102nd, is the most hypereutrophic. For reference, Lake Nacogdoches was ranked number one.


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Historical Data Review of Impaired Segments and Texas pH Evaluation Project Potential Sources pH Impairment

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SECTION 4

HISTORICAL DATA REVIEW OF IMPAIRED SEGMENTS AND POTENTIAL SOURCES OF pH IMPAIRMENT

4.1 Segment 0105—Rita Blanca Lake Rita Blanca Lake (Figure 4-1) is located in the extreme Northwestern Panhandle of Texas, south of Dalhart in Hartley County. Rita Blanca Creek was impounded in 1939, is owned by the Texas Parks and Wildlife Department, and is managed as a sanctuary for migratory birds, including 40,000-100,000 geese that visit the lake every year. A designated use of the lake is that of high quality waterfowl habitat (TNRCC 2000a). The lake is relatively small with a capacity of 12,100 acre-feet, a surface area of 212 ha and a maximum depth of 1.5 m. The Red River Authority (RRA 2008) states that the City of Dalhart WWTF is “the only significant inflow” (RRA 2008) and is supplemented by occasional rainfall (approx. 432-483 mm annually). The Dalhart WWTF is permitted for 1.5 MGD.

The local geology is highly alkaline limestone with high salt content that is expressed in the limnology of surface and groundwater in the region (see Table 3-4 for alkalinity and specific conductance in Rita Blanca Lake). The climate is also arid and these regional geological and climatic characteristics are consistent with systems dominated by evaporative processes (Gibbs 1970, Ground and Groeger 1994). 4.1.1 Historical Data Review

Segment 0105 is small and consists of one AU with one monitoring station (10060). Rita

Blanca Lake was first listed for pH exceedances in 2004 and currently ranks last among Texas reservoirs in TCEQ’s TSI, making it the most eutrophic lake in Texas for chlorophyll-a (CHLA) concentrations, secchi depth and total phosphorus concentrations. The CHLA mean from 14 samples was 349 μg/L. The mean Secchi depth was 0.08 m and an upward trend in algal content was apparent between 2006 and 2008 (TCEQ 2008c). The mean total phosphorus concentration was 3.36 mg/L and every sample assessed in the 303(d) list exceeded the total phosphorus and orthophosphate phosphorus screening levels. Ammonia and nitrate samples also consistently exceeded screening levels. Historical monitoring data for pH exists as early as 1972 and has continued with only a few brief interruptions through the present. Frequent pH exceedances above the current criteria of 9.0 occurred during the mid 1980s and again in recent years, 2002 – 2008. Since 2002, spring, summer, and fall had median pH values of 9.5, 9.7, and 9.8, respectively. Winter had a significantly lower median pH of 8.6.

Local geology is high in calcium carbonate (CaCO3), and alkalinity levels in Rita Blanca Lake reflected this fact with a range of 208-443 mg/L as CaCO3 from 2002 – 2007. The mean instantaneous DO was 11.4 mg/L and specific conductance was high, relative to Central and East Texas (Table 2-1), averaging 1267 μS cm-1. Interestingly, pH was not significantly correlated with a positive increase in DO%sat, as would be expected if algae and phytoplankton activity


4-2

Figure 4-1 Map of Rita Blanca Lake (Segment 0105).


4-3

were causing spikes in pH. This disconnect may be attributable to other factors driving DO levels such as microbial respiration processes and wind mixing—Dalhart wind averages approximately 20 km/h and is located in one of the windiest regions in the state (Berner International Corp 2008). Satellite images reveal several bright green drainage ditches leading from Dalhart to the reservoir, presumably draining runoff from residences and businesses (Figure 4-2). Clearly visible in the image are also several green circles of crop production; presumably from center-pivot irrigation.

Figure 4-2 Satellite image of Rita Blanca Lake, Hartley County, Texas (www.maps.live.com, accessed 08 August 2008).

4.1.2 Potential Sources of pH Impairment and Recommendations

The City of Dalhart WWTF is the dominant source of inflow to the lake, 40,000-100,000

migratory geese visit the lake every year, numerous drainage ditches lead from Dalhart to the lake, and crop circles from center pivot irrigation that dominate the landscape to the west and east may produce nutrient-rich runoff during infrequent wet-weather runoff events. The lake is also very shallow which allows for complete wind-mixing of nutrients, thus enhancing metabolic processes that contribute to the productivity of the lake. Cultural eutrophication† and lake management practices are clearly contributing to the hypereutrophy of the lake. Intense photosynthetic removal of CO2 likely is to blame for high-pH values. Although alkalinity is high in the region, it cannot buffer Rita Blanca Lake from pH spikes over 10 (Figure 4-3). This could be explained by high sodium in the region’s geology and surface waters (Table 2-1). Sodium bicarbonate is more soluble than CaCO3 and allows for larger accumulations of CO3

2- which subsequently hydrolyzes in water (Eq. 2) to produce hydroxyl ions (Boyd 1990). Thus, pH values above the criterion of 9.0 can be explained by primary production—enriched by cultural eutrophication—and the geologic context in which the eutrophication is occurring.

Rita Blanca Lake is experiencing cultural eutrophication and may be characterized as

hypereutrophic. The lake periodically experiences pH exceedances more than 1 standard unit † The portion of eutrophication attributable to human development.


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Figure 4-3 Time history of pH for the impaired AU of Rita Blanca Lake, Segment 0105 (data for 1998 – 2006).


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higher than the upper pH criterion of 9.0. Since cultural eutrophication is an explanatory variable in the pH exceedances and the lake is part of the State of Texas park system, it would at first seem that the TMDL process should be a high priority for restoration of Rita Blanca Lake. However, the shallowness of the lake in addition to its climatic and geologic setting and the seasonal abundance of migratory birds are all conditions that support eutrophication and elevated pH readings and portend difficulties in implementing sufficient control measures to reduce pH exceedances. Careful consideration should be given prior to embarking on the TMDL process regarding the priority of this water body compared to others in the state and as to whether the watershed protection planning process or consideration of standards revision might be viable alternatives to a TMDL. 4.2 Segment 0229—Upper Prairie Dog Town Fork Red River Assessment unit 2 of the Upper Prairie Dog Town Fork Red River begins at the upstream boundary of Palo Duro Canyon State Park and ends at Tanglewood Dam. The lone sampling station for this AU is 18317, approximately 100 m below the dam (Figure 4-4). TCEQ has records from other stations further downstream in AU 2 but the data predates the period of record for the 2006 303(d) list (data ranged from 1992 – 1998) and there were no exceedances at these stations. The City of Amarillo WWTF has two outfalls with a combine permitted discharge of 12 MGD. Outfall 001 is approximately 1 km below sampling station 18317, and outfall 002 is in the upper end of Lake Tanglewood. The segment is located in the middle of the Texas Panhandle in the Southwestern Tablelands ecoregion (Table 3-2), the arid “badlands.” Gustavson et al. (1982) described the geology as karst with an abundance of salts, gypsum, and dolomite. 4.2.1 Historical Data Review

This segment was first listed for pH in 2006 and, as of 2008, 8 of 13 samples have

exceeded the 9.0 criteria (Figure 4-5). During the last 5 years of record, the pH has not dipped below 8.2—not surprising considering the segment’s high alkalinity (156-375 mg/L as CaCO3). High pH readings occurred most often during the spring and summer, which had median values of 9.2 and 9.5, respectively. Dissolved oxygen hovered between 9 and 12 mg/L during the winter months and 3-8 mg/L during the summer. A possible explanation for the seasonal difference in DO is that flow over Tanglewood Dam (Figure 4-6) is greater during the winter and lower during the summer when a local power plant recycles much of the discharge from the City of Amarillo WWTF, outfall 002 (Pat Bohannan, personal communication, October, 2008). This implies that during summer months, seeps, which are often DO-poor, are a more significant source of flow in the channel. Further study is needed to confirm this speculation.


The Red River Authority considered nutrient-rich discharge from Lake Tanglewood and the City of Amarillo WWTF possible sources of eutrophication in the AU (RRA 2007). The TCEQ ranked Lake Tanglewood 91st in TSI and it has a CHLA TSI trophic class of hypereutrophic. Nitrate, orthophosphate phosphorus, and total phosphorus (mean 1.18


4-6

Figure 4-4 Map of Upper Prairie Dog Town Fork Red River (Segment 0229).


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Figure 4-5 Time history of pH for the impaired AU (station 18317) of Upper Prairie Dog Town Fork Red River, Segment

0229 (data for 2003 – 2006).


4-8

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mg/L) exceeded screening levels in all 16 lake samples as of 2006. The spillover dam exposes nutrient-rich, shallow outflow to full sun before it enters the stream bed less than 100 m upstream from station 18317 (Figure 4-6). As mentioned above, this might be a more significant source of nutrients during winter months when City of Amarillo WWTF flows are not recycled to the extent they are during the summer. Because the greatest number of exceedances occurred during the spring and summer, further research is needed to determine the seasonal impact of Lake Tanglewood overflow on the water quality at station 18317.

Figure 4-6 Satellite image of Lake Tanglewood dam and station 18317 of Segment 0229, Randall County, Texas (www.maps.live.com, accessed 08 August 2008).

Access may have restricted AU 2 sampling to station 18317, but it is questionable whether this site is representative of the entire assessment unit. Because of its proximity to Lake Tanglewood, station 18317 is strongly influenced by the eutrophication of the reservoir, hydrologic modification to the stream from presence of the dam, and the exposure of the shallow flow as it descends over the dam. The TCEQ should consider evaluating the availability of additional or alternative sample sites that would be distributed more evenly throughout the assessment unit. Data from additional sample sites should be added to the existing body of data and the AU re-evaluated before a decision is made regarding TMDL actions.

Because the City of Amarillo WWTF outfall 002 is downstream of station 18317 and pH

is not a concern in downstream AU 1 of Upper Prairie Dog Town Fork, it cannot be determined whether the WWTF discharge at outfall 002 is a source of pH impairment for the lower portion of AU 2. However, AU 1 did have several samples exceeding screening levels for CHLA, nitrate, orthophosphate phosphorus, and total phosphorus. It is within reason to presume that the lower portion of AU 2 could experience pH exceedances associated with WWTF discharge-supported eutrophication but the evidence is circumstantial. Unless additional sampling sites are monitored downstream, efforts to address this water quality concern should be directed at upstream processes affecting eutrophication in Lake Tanglewood.


4-9

4.3 Segment 0401—Caddo Lake Caddo Lake spans portions of Marion County, Texas, and Caddo County, Louisiana. It has a surface area of approximately 12,140 ha, an average depth of one meter, and a maximum depth of about three meters. Naturally impounded by a log jam that originated during the period 1799 – 1835, it has been permanently impounded since 1914 by earthen and concrete dams operated by the U.S. Army Corps of Engineers for purposes of water supply and recreation (USACE 2008). The lake is fed primarily by Big Cypress, Little Cypress, and Black Cypress Creeks. Big Cypress Creek flows out of Lake of the Pines and through the City of Jefferson before its confluence with the other tributaries to form the upstream marshy portion of the lake.

Nearly a third of Caddo Lake is a cypress swamp (Darville et al. 1998), situated in the

upper half of the lake. The watershed is heavily forested and is characterized by acid soils, low alkalinity (mean of 18 mg CaCO3 L-1), and relatively high amounts of rainfall (average of 1168-1270 mm annually). Warm annual temperatures also support dense communities of macrophytes and high rates of microbial decomposition in Caddo Lake’s shallow waters. These natural conditions predispose the lake to low pH.

4.3.1 Historical Data Review

Caddo Lake is divided into six AUs numbered 1, 2, 3, 5, 7, and 8. Assessment units 2, 3,

and 5 are currently listed for low-pH and the segment has been listed since 1996. According to recent data the majority of exceedances occurred in AU 2 at station 10286 and in AU 5, station 14236 (Figure 4-7) and from February 2003-July 2004 (Figure 4-8). The three impaired AUs for pH exceedances are also included on the 303(d) list for depressed DO. According to findings by Crowe et al. (2007), pH exceedances in the upper mid-lake during the same time period were associated with high flows from tributaries, especially following dry spells. The upper mid-lake is not included in impaired AUs 2, 3, and 5.

Darville et al. (1998) delineated three primary sub-habitats within the Caddo Lake

ecosystem using discriminant analysis with over 93% accuracy: riverine, wetland, and lake (open water). Their analysis used 20 water quality parameters, including pH, alkalinity, and assorted nutrients, and covered 79 sampling sites during the summer of 1997. Their pH data ranged 5.7-8.4 with the lowest readings occurring in the wetland sites and the highest readings in open lake water, presumably due to greater phytoplankton productivity and lower microbial respiration in open water. Mean alkalinity of their combined sites was 16 mg/L as CaCO3. Total phosphorus and nitrate concentrations were much lower in lake habitats, and Darville et al. attributed this to assimilation by phytoplankton. Finally, it is anticipated that conditions will be suitable in the wetland habitats for high microbial activity, which lowers the p:r ratio for the system and, typically, the pH as well.

The City of Jefferson is about 18 river miles upstream of Caddo Lake and has a WWTF outfall that discharges into an unnamed tributary of Black Cypress Creek about 10 km upstream of the confluence with Big Cypress Creek (Figure 4-7). The facility is permitted for 0.55 MGD. Big Cypress Creek below Lake of the Pines (Segment 402) is listed for low pH in the lower and


4-10

Figure 4-7 Map of Caddo Lake and Big Cypress Creek below Lake of the Pines (Segments 0401 and 0402).


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Figure 4-8 Time history of pH for impaired AUs of Caddo Lake, Segment 0401 (data for 1994 – 2006).

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4-12

middle assessment units of the river immediately upstream of Caddo Lake, and it is the next segment discussed. Black Cypress Creek is listed for depressed DO concentrations and bacteria concerns.

4.3.2 Potential Sources of pH Impairment and Recommendations Point source contributions are scarce around Caddo Lake. The City of Jefferson WWTF has a relatively small permitted discharge, which flows a long distance to Caddo Lake through a productive stream system—capable of rapid nutrient assimilation. The WWTF effluent is unlikely to have direct significant effects on the lake’s limnology. Nonpoint nutrient sources are also relatively scarce since only 10% of the watershed is dedicated to agriculture (NETMWD 2005). The NETMWD also reported that despite “substantial” retirement and recreational development around the lake, 88% of the land use was still forest and wetlands. The degree to which on-site sewage facilities (OSSFs) might contribute to nutrient enrichment could not be ascertained in this “desktop” study and remains largely an unknown.

It is fully anticipated that observed pH values and exceedances below the lower criterion for Caddo Lake are dominantly the result of natural conditions in the lake’s assessment units that are impaired. Respiration processes in swamps result in acid waters as CO2 is produced in large amounts, especially in a setting with naturally acidic soils and low alkalinity in surface waters. Thus, buffering capacity is naturally low on account of the geological and climatic context of Caddo Lake and its contributing watershed. Generally, swamps—some of which can be extremely acidic—are documented to support thriving communities of plants, animals, and microorganisms (Cain 1928, Benke et al 1984). More specifically, the Louisiana Department of Wildlife and Fisheries (Lester et al 2005) listed 18 animal species of concern found in cypress-tupelo-blackgum swamp habitats, and the Texas Parks and Wildlife Department (TPWD 2008) describes a rich fish diversity (71 species) and many kinds of waterfowl, mammals, and vegetation that are flourishing under the acidic conditions of Caddo Lake.

Caddo Lake is a unique and important natural resource of the state that warrants protection of its water quality. At the same time, the previously discussed findings of Darville et al. emphasized the role sample location has in the assessment process. The impaired AUs in Caddo Lake are all in wetland and riverine habitats where the p:r ratio is lower than in open water habitats and where lower pH values would be anticipated than in the main body of the lake. The majority of pH exceedances in the impaired AUs occurred during the 18-month period of February 2003 through July 2004 and for the subsequent three years of monitoring only one excursion has been observed (Figure 4-8). The pH exceedances during this period have been associated with high flows that followed dry periods (Crowe et al. 2007) and a similar pattern of pH exceedances was also noted during the same period in the major tributary to Caddo Lake ─ Big Cypress Creek (which is the next segment discussed). It is suggested that the pH exceedances in Caddo Lake may be related to characteristics of both the wetland and riverine habitat included in the impaired AUs and hydrologic patterns that were reported to have perpetrated the rash of exceedances in 2003 and 2004.

Continuation of the monitoring of Caddo Lake is recommended as well as investigation of the implications of station location on monitored pH. Additionally a re-evaluation of the low


4-13

pH criterion should be considered, since the excursions seem to be attributable to natural conditions present in the lake.

4.4 Segment 0402—Big Cypress Creek below Lake O’ the Pines Big Cypress Creek flows from below Lake of the Pines to the marshy headwaters of Caddo Lake (Figure 4-7). The City of Jefferson (Marion County) is the only major municipality discharging directly into the segment’s watershed and its WWTF discharges into a tributary of Black Cypress Creek approximately 10-km upstream of Big Cypress Creek. The watershed is well-forested (81%) with pine, cypress, and a mix of hardwoods including sweetgum (NETMWD 2005), especially in the eastern half. Soils are acidic, well-drained sandy-loams and the region receives approximately 1168-1270 mm annually of precipitation. 4.4.1 Historical Data Review

The two downstream AUs (AU 1 and AU 2) of Segment 0402, representing the 32 km between Black Cypress Creek and Caddo Lake, were first listed for low pH in 2000. Low pH exceedances were recorded in 17% and 13% of samples in AU 1 (stations 10295, 15022) and AU 2 (stations 14471 and 16254), respectively, and most of the exceedances occurred from February 2003 – July 2004 (Figure 4-9), as was experienced in Caddo Lake. Winter months (December – February) contained particularly low readings (range 5.4-5.9) and account for 41% of the exceedances. This seasonality is particularly stark considering only 26 samples were taken during the winter compared to 37, 57, and 28 samples for spring, summer, and fall, respectively. Calcium carbonate is nearly absent from the soil in the region (Griffith et al. 2004) and thus alkalinity in the impaired stations is extremely low (6-29 mg/L as CaCO3). Precipitation pH averages around 4.8 (Figure 2-1).

Assessment units 1 and 2 are also listed for low DO. The impaired stations are located

near the marshy headwaters of Caddo Lake where respiration is expected to meet or exceed production (Darville et al. 1998). Relative to West Texas, the riparian zone is more densely vegetated and contributes a larger amount of leaf litter and large woody debris to the river channel, food resources for microbes and macroinvertebrates (TNRCC 2000b). Warm humid conditions support a high metabolism in East Texas waterways that at times becomes anoxic (Darville et al. 1998; NETMWD 2005).


The natural environment predisposes Big Cypress Creek to relatively low pH throughout

the year but winter exceedances predominate in measured values. This winter predominance is likely tied to sap-drop, increased groundwater contribution to surface water, and microbial decomposition of leaf litter. Significant effects on pH by sap-drop were discovered in the same ecoregion 120 km to the southwest (see Neches River above Lake Palestine, Section 4.7).


4-14

Figure 4-9 Time history of pH for impaired AUs of Big Cypress Creek below Lake O’ the Pines, Segment 0402 (data for 1994 – 2006).

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4-15

There are few cultural eutrophication agents in the watershed: the three municipalities, Jefferson, Karnack, and Uncertain, all have populations under 3,000 and the only major discharger, the City of Jefferson WWTF outfall (0.55 MGD permitted flow), discharges into Black Cypress Bayou more than 10 kilometers upstream of Big Cypress Creek. Lake O’ the Pines marks the upstream boundary of Segment 0402. Lake O’ the Pines is considered moderately eutrophic with occasional exceedances above nutrient screening levels. Considering the productivity of this system, the assimilative capacity of Black Cypress Bayou and Big Cypress Creek should be sufficient to attenuate most of the nutrient impact from Lake O’ the Pines and the City of Jefferson WWTF before streamflows reach the downstream AUs of Big Cypress Creek, though further research is needed to confirm this supposition.

As with Caddo Lake, many natural factors drive acidic processes in Big Cypress Creek

and cultural eutrophication does not appear to be a significant contributor to the pH exceedances. For these reasons, re-evaluation of the pH standard should be considered in this segment. The majority of exceedances occurred in sluggish wetland areas and during the winter season, which also suggests a need for an expanded sampling effort that extends the spatial and temporal scope of the dataset. 4.5 Segment 0507—Lake Tawakoni Lake Tawakoni is the most upstream reservoir of the Sabine River and it is situated about 48 km east of Dallas. It was dammed in 1960 for water supply and has evolved into a source for recreation. The north arm of the reservoir is fed by Cowleech Fork Sabine River and it is the only portion of Lake Tawakoni listed for any impairment (pH or otherwise) on the 2008 303(d) list (Figure 4-10). The depth of the Cowleech Fork arm ranges from 0 to 4.8 m. (TWDB 2003). The Cowleech Fork arm drains 458 km2 and much of the watershed has agricultural land uses such as grazed land, hay production, and crop production such as wheat, cotton, and sorghum. Cowleech Fork is intermittent until its confluence with Long Branch Creek which receives effluent from the City of Greenville WWTF (4.23 MGD permitted) about 17 km upstream of Lake Tawakoni. According to a special study by the Sabine River Authority (SRA 1999), the river becomes perennial at this juncture. Based on this circumstantial evidence, a considerable portion of flow into the Cowleech Fork of Lake Tawakoni would be WWTF effluent during dry periods. More study is needed to confirm this speculation. Ground and Groeger (1994) classified Lake Tawakoni as an East Texas reservoir where pH, specific conductance, alkalinity, and other measures of ionic composition were low (see Table 2-1). Indeed, alkalinity in the current dataset only ranged from 36-94 mg/L as CaCO3, and specific conductivity was 80-225 μS cm-1. Instream pH readings in the Neches River, just one county to the south, were heavily influenced by groundwater and regularly dropped below a pH of 5.0 (Crowe 2008). 4.5.1 Historical Data Review

pH is the only analyte for which the Cowleech Fork arm of Lake Tawakoni is listed, although some exceedances were noted for screening levels of CHLA, nitrate, and orthophosphate phosphorus. Data from stations 17836 and 10440 were used to determine


4-16

Figure 4-10 Map of Lake Tawakoni (Segment 0507).


4-17

attainment based on the pH criteria for this area. Seasonality of pH was significant in a Kruskal-Wallis test (X = 65.08, p < .0001) and is graphically apparent in the recent pH data for Cowleech Fork arm (Figure 4-11). Most pH exceedances occurred during the summer (56%) when the median pH was 8.9 (range 7.8-9.3). Summer-winter (z = -6.78, p < .0001) and summer-spring (z = -6.29, p < .0001) differences were the most distinct in Wilcoxon two-sample z-tests with summer having the higher pH.

Photosynthetic assimilation of NO3

- can cause alkalinity to increase with an accompanying rise in pH (Stumm and Morgan 1996), in addition to pH increases from CO2 uptake during photosynthesis. In Lake Tawakoni, there was a significant negative correlation between pH and NO3

- (r = -0.74, p < .0001) suggesting uptake of NO3- by primary producers

caused elevations in alkalinity and pH. CHLA was positively correlated with pH (r = 0.69, p < 0.0001), further supporting the role of a high p:r ratio and photosynthesis in increasing pH.


Evidence that cultural eutrophication is the most likely cause for high pH in Lake

Tawakoni is observed in a) the fact that natural environmental factors work to bring the pH down, b) summer peaks in pH, and c) significant correlations between pH and NO3

- (negative) and pH and CHLA (positive). Summer pH spikes coincide with the peak season for algae growth (indicated by CHLA) when temperatures are warm and sunlight is more abundant. However, algae is only an indicator of nutrient enrichment; the evidence for cultural nutrient enrichment is found in an examination of the potential point and nonpoint sources in the watershed. MB Wastewater Services L.L.C. is a permitted discharge immediately near station 17836 (Figure 4-10), but the permit was not issued until January 2006 and no discharge seems to have occurred before the end of the assessment period-of-record in November 2006. The City of Greenville WWTF could be a significant source of nutrient-enriched flows during dry weather for the Cowleech Fork arm. Exceedances of pH occurred most often during July – September when precipitation and lake levels were generally low. Because of proximity to the Cowleech Fork arm and size of discharge (permit limit of 4.23 MGD), the City of Greenville WWTF is a potential contributor of the nutrient enrichment causing cultural eutrophication and summer pH exceedances in this portion of Lake Tawakoni. However, nutrient loadings to the lake from nonpoint sources during the typical highest rainfall months of spring and early summer could also contribute to the conditions resulting in pH exceedances during mid and late summer. Regarding nonpoint source loading contributions, McFarland et al. (2001) made similar conclusions in the North Bosque River which is periodically intermittent and fed by a WWTF in the upper reaches before entering Lake Waco, a reservoir with nutrient enrichment concerns.

Significant exceedances in pH appear limited to the Cowleech Fork arm of the lake and are likely the result of cultural eutrophication processes beginning to be manifest in this upper arm of Lake Tawakoni that functions as a transition from riverine to lacustrine environments. Spikes occur shortly after high-rainfall months of the year, suggesting nonpoint source pulses of nutrients, along with WWTF flows, could be responsible for a large portion of the enrichment that spurs algal blooms in the Cowleech Fork arm and the corresponding exceedances in pH. Since the pH exceedances are associated with the typical summer season of maximum primary productivity, the impairment appears to be associated with nutrient enrichment. Hence, the pH


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Figure 4-11 Time history of pH for the impaired AU of Lake Tawakoni, Segment 0507 (data for 1999 – 2006).


4-19

exceedances in a reservoir with limited buffering capacity (i.e., relatively low alkalinity) are likely a harbinger of cultural eutrophication, an issue that can be addressed through the TMDL process. 4.6 Segment 0605—Lake Palestine Lake Palestine in northeast Texas was dammed in 1962 for municipal and industrial water use. There are numerous communities surrounding the lake that utilize this resource and the lake experiences heavy recreation use. The lake has a conservation pool capacity of 370,908 acre-feet but during a period of dry weather from spring 2005 – fall 2006 the storage was considerably lower than normal and dropped as low as 297,000 acre-feet in October 2006. The region receives on average about 864-990 mm of precipitation a year with peak median rainfall in May (114 mm) and June (86 mm) and low median rainfall in December – February (39-49 mm). Despite low pH in regional soils (Griffith et al. 2004), shallow groundwater (Crowe 2008), and some surface streams [e.g. Neches River above Lake Palestine (Segment 0606), Table 3-4], several stations in upper and mid Lake Palestine are listed for high pH exceedances (Figure 4-12). The City of Tyler (Westside) WWTF discharges into Black Fork Creek, a tributary of the Neches River above Lake Palestine, approximately 10 km upstream of Lake Palestine. This WWTF has a permitted discharge of 13 MGD; fully 10 times the discharge of the other six permitted facilities in the watershed combined (Crowe 2007). The City of Chandler WWTF (0.5 MGD permitted) discharges into a drainage ditch almost adjacent to the west shore in the upper arm of the lake just below the Neches River. Assessment unit 3 was first listed in 2006, followed by the addition of assessment units 9, and 10 in Lake Palestine in 2008. Assessment unit 3 has one sampling station, 16346, located on the east shore of the middle portion of the lake where the City of Tyler operates a raw-water intake. Crowe (2007) reported higher phytoplankton abundance here than in the upstream AUs where macrophytes were more abundant. Assessment unit 9 (stations 18371 & 18557) is located just inside the Flat Creek arm near the town of Moore Station. Assessment unit 10 (station 18643) is on the east shore immediately below the confluence of Kickapoo Creek and the Neches River; a transition zone with large amounts of submerged and floating macrophytes. 4.6.1 Historical Data Review

Lake Palestine is classified hypereutrophic and has a TSI ranking of 88 (TCEQ 2008c).

A large number of CHLA exceedances were noted in all three AUs resulting in a status of Concern for Screening Level in the 2008 303(d) list. In a t-test of seasonality for pH, all seasons differed significantly except for winter-spring (graphically depicted on Figure 4-13). Seventeen of the 20 exceedances in Segment 0605 occurred from August – October (Figure 4-14). The other three occurred in May, June, and November. The exceedances are not extreme ─ most were under 9.0 and the highest, 9.4, occurred only one time (Sept. 2002, station 16346). During the dry weather and low-storage period of 2005 – 2006, pH at all stations was below 8.0. Pearson correlation analysis indicated a significant relationship between pH and CHLA (r = 0.61, p < 0.0001) and pH and DO%sat (r = 0.60 p < 0.0001).


4-20

Figure 4-12 Map of Lake Palestine (Segment 0605) and Neches River above Lake

Palestine (Segment 0606).


4-21

Figure 4-13 Seasonality of pH in Lake Palestine, assessment units 3, 9, and 10 combined.

Center bars are medians, plus signs are means and boxes without overlapping notches are significantly different (p < 0.05). Width of boxes denotes relative n (winter = 14, summer = 18).

4.6.2 Potential Sources of pH Impairment and Recommendations Seasonality, CHLA, and DO%sat were all significantly correlated with pH and the lake has been listed as hypereutrophic by the TCEQ (2008c), which all strongly suggest that exceedances are a response to photosynthetic activity by primary producers. Where macrophytes and attached algae are dominant, light penetration is reduced and this lowers phytoplankton abundance. This is the case in the shallow, turbid, upstream reaches where macrophyte productivity is high yet DO and pH are not concerns. Phytoplankton is the dominant primary producer where the sampling stations are located in the impaired AUs, including station 18643 (AU 10), which is located in the upper lake east shore but was noted by Crowe (2007) for high CHLA.

There are only two likely point sources of nutrient enrichment, based on their size and

location, affecting the listed assessment units: City of Tyler (Westside) WWTF and The City of Chandler WWTF. Art Crowe (TCEQ Region 5, Tyler Office, personal communication, July 2008) also confirmed the likely impact of the Tyler facility which discharges into Black Fork Creek, a tributary of the Neches River above Lake Palestine. Interestingly, several other sampling stations exist along the Neches River and Lake Palestine in closer proximity to the Tyler outfall and they are not listed for any impairment. The maintenance of pH below 8.5 at these stations, in spite of nutrients from WWTF effluent, is likely attributable to three things, 1) the influence of acidic groundwater into the narrow riverine channel of the Neches, 2) canopy cover that discourages algal growth, and 3) the upstream influx of acidic flows from the Neches

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Figure 4-14 Time history of pH for impaired AUs of Lake Palestine, Segment 0605 (data for 1999 – 2006).

AU 3 16346 AU 9 18371 18557 AU 10 18643


4-23

River above the Black Fork Creek confluence. These natural environmental sources of low-pH waters and barriers to eutrophication are removed once the Neches River opens into the lacustrine zone of Lake Palestine. Urban nonpoint sources abound in the watershed with lake-front homes, recreation facilities, marinas, etc. Besides Tyler, with a population of 83,650 and Chandler (pop. 2,099), there are four towns with populations under 800 situated within 10 km of the reservoir.

A TMDL seems reasonable in this segment where cultural eutrophication appears very likely to be at the root of high pH exceedances with the sources potentially being both point and nonpoint sources. Natural processes explaining high-pH exceedances are simply lacking for Lake Palestine. In addition, because problems are restricted to a season (late summer-early fall) and a particular group of primary producers (phytoplankton) and are within close range of the 8.5 pH criteria, it is recommended that a study of inter-annual phytoplankton structure and function be conducted (sensu Roelke et al. 2004) to determine whether a focused control mechanism could be put in place to limit blooms of phytoplankton during certain times of the year.

4.7 Segment 0606—Neches River above Lake Palestine The Neches River above Lake Palestine begins in Henderson/Smith Counties, 6.7 km downstream of FM 279, and ends at Rhines Lake Dam in Van Zandt County (Figure 4-12). The segment is in the same ecoregion as Lake Palestine (35a) and is subjected to approximately the same climate. The immediate watershed is less populated than Lake Palestine and land use is more agricultural based on a qualitative assessment of maps and satellite images. The City of Van (pop. 2,362) is the only local municipality that drains into the segment directly (or nearly so) upstream of the impaired assessment units. It has a WWTF (0.6 MGD permitted) with an outfall in Big Sandy Creek about 4 river kilometers upstream of its confluence with the Neches River. It is worth repeating that low pH and alkalinity are characteristic of the regional soils and waterways (Griffith et al. 2004, Crowe 2008, TNRCC 2000b). Due to extremely low alkalinity (Ground and Groeger 1994), pH fluctuations of higher magnitude and a generally lower mean than West Texas streams are to be expected. 4.7.1 Historical Data Review

Only the upper two AUs (2 & 3) are listed for low pH exceedances. Station 10597 was

used to assess AU 2, and station 10598 was used to assess AU 3. They were first listed for pH in 2002 but have been listed for low DO since 1996. The lowermost assessment unit (AU 1) is listed for bacteria and was first listed for bacteria in 2008. Seasonality was not significant for pH, but exceedances only occurred between August and March with 7 of the 11 exceedances occurring between October and January. Excursions of pH were almost an annual event from 1998-2006 and ranged between 4.9 and 5.8 except for an event in late 2006 that dropped the pH in the lower station (10597) to 3.5 (Figure 4-15). This event was tied to moderate rain events (approximately 25-40 mm) in mid-October that ended a prolonged period of dry weather in the basin (Crowe 2008). The rain was not sufficient to cause runoff but filtered into the soil, re-emerging several weeks later as isolated pools in the river channel that had been dry at the start


4-24

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Figure 4-15 Time history of pH for impaired AUs of Neches River above Lake Palestine, Segment 0606 (data for 1995 –

2006).


4-25

of the month. Crowe (2008) postulated that seasonal sap-drop and leaf-fall coupled with the timing and intensity of rainfall contributed to the low pH. Citing the high abundance of hardwoods in the watershed, Crowe suggested that when the trees go dormant it provides shallow groundwater a longer period of saturation time in the sulfuric soils characteristic of the area. A mild sulfuric acid is the product that enters the streambed through seeps following low-runoff rains. Because rainfall is typically stronger and more regular than it was in 2006, such extreme drops in pH are not common. Nevertheless, the 2006 event appears to have been a natural process driven by hydrogeology, climate, and vegetation.

The median pH across all assessed samples was 6.7 and DO averaged 4.4 mg/L. These values are indicators of low p:r ratios, and it is reasonable to assume that microbial breakdown of leaf litter is a major driver of biochemical processes in this reach of the Neches River. The dense canopy likely drops large amounts of organic matter into the stream and shades the channel with strong effect (based on satellite imagery), precluding significant algal growth and the commensurate photosynthetic assimilation of CO2. 4.7.2 Potential Sources of pH Impairment and Recommendations

Low-pH exceedances do not appear to be unnatural in this stream based on the evidence presented above. There is little readily identifiable as significant point or nonpoint sources in the watershed of the impaired AUs, since the major discharger and urban area (i.e., the City of Tyler) would impact the Neches River below the impaired AUs. The regional alkalinity is naturally so low that pH “perfect storms” will occur periodically with little remedy. There is simply little in the hydrogeology to buffer against dramatic swings in hydrogen ion concentration.

Under the ambient conditions identified in this study, it would be reasonable to re-evaluate the lower pH criterion for Segment 0606, since the pH exceedances appear to be associated with natural conditions rather than cultural eutrophication as the term is broadly defined in this study. 4.8 Segment 0803—Lake Livingston Lake Livingston, an impoundment of the Trinity River in Southeast Texas, was dammed in 1969. It is the largest dam built for water supply in the state of Texas, the lake covers 33,590 ha and has 1,750,000 acre-feet of water at normal pool elevation (40 m). It has an average depth of 7 m, a maximum depth of 27.4 m, and more than 724 km of shoreline. There are numerous recreational facilities on the lake shore which is heavily developed with residential neighborhoods, particularly along the east shore in Onalaska (pop. 1,174) and West Livingston (pop. 6,612). Huntsville (pop. 35,078) is the only major city in the watershed and has a WWTF (1.6 MGD permitted) that discharges into a tributary about 20-km upstream of the west fork of Lake Livingston. The Trinity River is the major tributary contributing flow into the impoundment. The lake is located in the Southern Tertiary Uplands ecoregion (35f) where longleaf pine abounds along with some open beech forests (Table 3-2). Soils are sandy-loamy and generally acid (pH ranges about 4.5 – 7.5) with very low alkalinity. Rainfall totals about 1090-1245 mm


4-26

per year; May is the wettest month (median 107 mm) and July is the driest (53 mm). However, precipitation is appreciable throughout the year with 76-102 mm falling each month from September through January. 4.8.1 Historical Data Review

Assessment units 1 (stations 10899, 14003, and 14004) and 6 (stations 10911 and 14010)

were listed for the first time in 2008 for high pH concerns (Figure 4-16). Assessment unit 1 is located near the dam and 14 of 104 samples were above the 9.0 criteria. The median pH at AU 1 was 8.2. All pH exceedances in the segment were recorded during summer months (June – August) except one in May 2005, a year that accounted for 6 of the 14 exceedances (Figure 4-17). Assessment unit 6 is located in the mid-lake region between Onalaska and West Livingston, centered on US Highway 190. Seven of the eight exceedances in AU 6 occurred in the summer and only two of the exceedances were recorded at station 14010. Six of the eight exceedances were from 2003, the other two were in the summers of 2000 and 2001, leaving no exceedances from 2003 – 2006 in AU 6. Across both AUs all but two samples in exceedance were taken after 13:00 hours and most were taken after 14:00 hours, which are sample collection times favoring high pH values from photosynthesis and CO2 uptake processes. An anonymous source at the Trinity River Authority (TRA) cited high turbidity in AUs 7-11 (upper reservoirs and coves) to explain the lack of phytoplankton-induced pH exceedances in those portions of Lake Livingston (personal communication 28 July 2008). For the combined dataset of impaired AUs 1 and 6, summer pH values are statistically higher (p < 0.05, pH meansummer = 8.8) than those of the other three seasons (Figure 4-18).

Lake Livingston is classified as hypereutrophic and ranked 73rd among Texas reservoirs

(TCEQ 2008c) based on the Carlson TSI index. Throughout the reservoir (including the AUs listed for pH) nitrate, total phosphorus, and orthophosphate phosphorus are a concern based on exceedances of screening levels. The upper arms of the reservoir appear very eutrophic in satellite images based on their green and olive-green color; however, the upper portion of the reservoir has not experienced excessive pH values.

In late September 2005, Hurricane Rita created large waves (up to 1 m) and surges that

damaged the upstream side of Livingston Dam. This event occurred within the period of record assessed by the 2008 303(d) report (TCEQ 2008a); however, no exceedances were recorded after August 2005, and no atypical pH patterns were noted in the months following Rita. It is concluded that Hurricane Rita, as a large episodic event for the lake, did not in its aftermath exacerbate pH excursions.


The seasonality of the exceedances, the time of day they were recorded, the high nutrient

loads, and the hypereutrophy of the lake point to algal blooms as the driver of pH exceedances in Lake Livingston. Because the natural ecology of the region should predispose the lake to low pH, it is likely that cultural eutrophication is to blame for the nutrient enrichment.


4-27

Figure 4-16 Map of Lake Livingston (Segment 0803).


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4-29

Figure 4-18 Seasonality of pH in Lake Livingston, assessment units 1 and 6 combined.

Center bars are medians, plus signs are means, and boxes without overlapping notches are significantly different (p < 0.05). Width of boxes denotes relative n (fall = 21, summer = 57).

There are over a dozen minor permitted discharges (< 0.3 MGD each) in the lower half of the lake alone and nearly a dozen more occupy space very close to the lake in the upper half. Waterwood MUD No. 1 (0.1 MGD) empties into a tributary of a cove about 1 km upstream of 14010 in AU 6 and this could be a point source of steady nutrient enrichment locally affecting the mid-lake region where the sampling station is located. The largest outfall near the lake is the City of Trinity (0.6 MGD; pop. 2,721) between the two northwest arms. Because these permitted facilities are small and the lake volume is so large, point sources surrounding the lake probably do not pose more than localized nutrient concerns.

The lake is a major center for recreation and is surrounded by residential neighborhoods,

marinas, golf courses, and businesses. Urban runoff must be a significant source of nutrient loading throughout much of the year based on monthly precipitation records. It would be useful to study the relative nutrient contributions of urban and agricultural runoff and their effects on primary productivity in the lake.

Finally and likely most importantly, Lake Livingston is in the Trinity River Basin which

is heavily impacted by the urban runoff and WWTF effluents of the Dallas-Fort Worth Metroplex. The enormous volume of water flowing into the Trinity River from point and nonpoint discharges in Dallas-Fort Worth begs attention, in spite of the distance of Lake Livingston from the cities. Unfortunately, such a thorough investigation of Trinity River inflows

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and Dallas-Fort Worth area contributions to the pH excursion issue in Lake Livingston was beyond the scope of this study. It is noted, however, that all AUs in the Trinity River above Lake Livingston (Segment 0804) for which there were sufficient data to allow assessment are indicated to have a concern for screening level exceedances for CHLA, nitrate, orthophosphate phosphorus, and total phosphorus (TCEQ 2008d) and that the most downstream U.S. Geological Survey gauge before Lake Livingston had an annual average flow of 216 cms (7,627 cfs) for the period of 1988-2007. This information on nutrient screening level exceedances and large annual flows in the Trinity River immediately above Lake Livingston bespeaks very large nutrient contributions to the lake from its major tributary, the Trinity River.

The symptoms of the high pH exceedances in some AUs of Lake Livingston are most likely associated with seasonal algal blooms and generally high phytoplankton concentrations in the reservoir as a response to cultural eutrophication. The watershed of Lake Livingston is large (multiple thousands of square miles) and the watershed includes the Dallas-Fort Worth Metroplex, all of which indicate a myriad of nutrient sources contributing to the lake. Despite the enormity of the undertaking, the source of the impairment appears to be cultural eutrophication which is amenable to being addressed by the TMDL process. 4.9 Segment 0818—Cedar Creek Reservoir Cedar Creek, a tributary of the Trinity River, was dammed in 1965 to provide water for Forth Worth and Tarrant County, Texas. The conservation storage is 644,785 acre-feet and the surface area is 133 km2 (TRWD 2008) with a maximum depth of 18.9 m. Three islands in the reservoir totaling 64.7 ha are protected by the TPWD as a bird sanctuary and Wildlife Management Area (WMA).

According to the TRA (2008), the watershed is not heavily populated but it is being

rapidly developed. The City of Terrell, roughly 38 km to the north, operates the largest WWTF (3 MGD permitted) in the watershed. The City of Kaufman is about 19 km to the north and has a WWTF permitted at 1.2 MGD. In addition, there are several smaller dischargers (0.125 - 0.626 MGD permitted) distributed along the length of the reservoir (Figure 4-19; note that the Cities of Terrell and Kaufman are not in the area shown on this map). West Cedar Creek MUD near the west side of the reservoir discharges into a spillway supplying the Trinity River to the southwest and does not affect the reservoir. Pasture (64%) and row-crop (6%) agriculture dominate the landscape around the reservoir and increased ranching has been cited as a cause of worsening soil erosion and sedimentation in the reservoir (CCWP 2008). The northern post-oak savanna (ecoregion 33a) is characterized by a gently rolling morphology with scattered hardwood forests and finely-textured, loamy soils. Rainfall averages 990 mm annually and May is the wettest month (median 114 mm). August is the driest month (median 38 mm) and winters are only slightly dryer than other seasons.


4-31

Figure 4-19 Map of Cedar Creek Reservoir (Segment 0818).


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4.9.1 Historical Data Review

There are 14 AUs in Cedar Creek Reservoir and beginning in 2002 all except AUs 10, 13,

and 14 have been listed for high pH exceedances. There are no other chemical or bacterial constituents causing impairment to the reservoir, but ammonia, total phosphorus, and orthophosphate phosphorus have been sufficiently elevated to cause concern for screening level exceedances. Chlorophyll-a concentrations have also been rising since 1992 (Figure 4-20) and since 1999 have exceeded screening levels numerous times in most of the AUs. The DO%sat, an indicator of primary productivity, was somewhat correlated with pH (Pearson coefficient = 0.62, p < 0.0001) using data from all impaired AUs.

Nearly 90% of the exceedances in the reservoir were recorded during the summer (Figure

4-21). All seasons were significantly different (p < 0.02) from one another in Wilcoxon two-sample tests, with the greatest differences between summer-winter (z = -10.6, p < 0.0001) and summer-spring (z = -8.7, p < 0.0001) comparisons. Most non-summer exceedances occurred during fall and winter of 1999 – 2000; since then, exceedances have been strictly a summer phenomenon. There was a regional drought in 2005 – 2006 and by December 2006 the reservoir reached a record low of 95.69 m, 2.45 m below normal. Significant rains during the next several months quickly brought lake levels back to normal. There were no major changes in magnitude or frequency of pH exceedances during this time. Figure 4-20 Cedar Creek Reservoir chlorophyll-a 17-yr trend (CCWP 2008). Annual

percentage rate (APR) indicates the percentage increase in CHLA per year.

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AU 1 13845 16745 16748AU 2 16744AU 3 16743AU 4 13848 16749AU 5 16746AU 6 15812 16741 16747 16750 17090AU 7 16739AU 8 16751 16752AU 9 13854 16753AU 11 16772AU 12 16774

Figure 4-21 Time history of pH for Cedar Creek Reservoir, Segment 0803 (data for 1997 – 2006). An outlier (11.6) from

station 16772 on 6 October 2004 was removed for graphical considerations.


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During the last decade, Cedar Creek Reservoir has trended towards higher median pH and the magnitude of exceedances has also increased. Figure 4-22 displays all of the pH samples from the impaired AUs, except for AUs 2, 3, 5, and 7 because these AUs were only sampled between 1999 and 2000 (representing a period outside of the 2008 assessment period) and should thus be excluded from long-term trend analyses. An outlier from AU 11 in 2004 was also excluded for graphical considerations. The paucity of exceedances during 2001 – 2002 may be attributable to a lack of sample data from AU 12 from 2001 – 2004; an assessment unit with a high rate of exceedances that is located in the uppermost portion of the reservoir (station 16774). Assessment units 2, 3, 5, and 7 accounted for nearly half of the abundant exceedances in 1999 – 2000, and when they are removed the frequency of summer exceedances during those two years is comparable to that of other years. Assessment units 2 (station 16744), 3 (station 16743), 5 (station 16746), and 7 (station 16739) represent the four major coves on the middle and lower east-side of the reservoir.

Figure 4-22 Cedar Creek Reservoir pH and trend lines for exceedances (red) and entire

dataset (black). An outlier was removed (pH = 11.6; 06 September 2004, AU 11) for graphical considerations.

Among mainstem AUs, the lower half of the reservoir comprising AUs 1, 4, and 6, had the lowest rate of pH sample exceedances and nine of the ten lowest pH values (6.5-7.2) were sampled in AUs 1 and 6. Seven of the ten highest values (9.4-11.6) were sampled in AUs 9, 11, and 12, which are located in the upper portion of the reservoir. The very highest values, 9.74, 9.76, and 11.6, were taken from AUs 12, 12, and 11, respectively. All of the coves except Lacy Fork (AU 10) and Cedar Creek (AU 13) were pH-impaired based on samples from 1999 – 2000. The pattern is not stark, but it does suggest greater pH problems in the upstream reaches and

y = 0.00018x + 1.30918

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coves of the reservoir, all of which are relatively shallow, presumably well-mixed, and receive waters from permitted dischargers and nonpoint sources. In the lower middle reservoir, AU 6 (stations 15812, 16741, 16747, 16750, and 17090) contained the most sampling stations (5) and contributed the most pH samples (156) and exceedances (38 of 123 mainstem exceedances), but the excursion rate was the second lowest in the reservoir. It is bounded on the north by Twin Creeks Cove. To the east is Enchanted Oaks, a residential community with a shoreline dominated by boat docks. The Cherokee Shores WWTF discharges into AU 6. Assessment unit 8 (stations 16751 and 16752) is in Prairie Creek Cove, a relatively narrow waterway surrounded on all sides by residential property and docks. It receives effluent from East Cedar Creek FWSD (0.626 MGD). Assessment unit 12 in the upper western arm and AU 11 in the upper mainstem surround the largest of the three islands protected by the TPWD for birds. 4.9.2 Potential Sources of pH Impairment and Recommendations The summer-seasonality of exceedances coupled with near-parallel perennial increases in both CHLA and pH promote an eutrophication explanation for pH impairment. Attempts to moderate pH should focus on reducing the nutrient loadings that enhance algae and phytoplankton abundance in the lake. As stated in Section 2 of this report, runoff is typically the largest contributor of nutrient pollution in Texas reservoirs. In 2007, the CCWP analyzed modeling data from Texas A&M University (TAMU) to determine the relative load contributions of sediment, phosphorus, and nitrogen, arising from urban land, WWTFs, pasture, and row-crops (Table 4-1; CCWP 2008). According to their analysis, agriculture is the largest contributor of loadings; row-crops, in particular, contribute a disproportionate amount of sediment and phosphorus to the reservoir. However, urban land use is expected to rise dramatically in the north watershed in coming decades (NCTCOG 2003) and this increase will likely diminish the extent of crop land and pasture. Yet urban runoff itself contributes more phosphorus per acre than pasture land, though less than crop land (see Table 4-1). Permitted discharges will also increase in size and number as the population in the watershed grows. Table 4-1 Watershed pollutant loadings (% contribution) per land use, adapted from

CCWP (2008). Source (% of total watershed) Sediment Phosphorus NitrogenUrban land (6.39%) 7.37 13.29 7.37 WWTFs 0.10 12.11 7.21 Pasture (63.52%) 15.73 22.57 44.06 Crop land (6.17%) 41.79 42.52 23.51

Cultural eutrophication in the middle portion of the reservoir is more likely to be

influenced by urban runoff and point source nutrient enrichment than the upper third based on the density of development in the middle reaches. The townships of Seven Points (pop. 1,145) and Tool (2,275) on the west side, and Mabank (2,151), Gun Barrel City (5,145), Payne Springs


4-36

(683), and Eustace (798) on the east side all lie adjacent to the lake or within 5 km of its coves. Prairie Creek Cove (AU 8) is a very narrow waterway (50-150 m wide) and is surrounded by the community of Gun Barrel City. East Cedar Creek FWSD (0.626 MGD permitted) discharges directly into the cove and as of 2003 delivered 23.38 mg/L of total nitrogen on average (CCWP 2008). The City of Mabank WWTF (0.4 MGD permitted) also discharges into a tributary of Prairie Creek roughly 5 km upstream of the cove.

Caney Creek Cove (AU 2) and Clear Creek Cove (AU 3) were only sampled for pH from

February 1999 – October 2000, but around 30% of the samples were above the 8.5 criteria. Furthermore, the coves connect to AU 1 and the station nearest to the coves in AU 1 (16748) recorded 12 of the 15 exceedances in the assessment unit. With only a few exceptions, exceedances in the coves coincided with exceedances at station 16748 while the near-dam stations in AU 1 (16745 and 13845) recorded pH levels within the upper criterion of 8.5. This pattern suggests problems in AU 1 are attributable to the location of a station in close proximity to the coves. The boundaries of the cove assessment units should be considered for extension towards the mainstem to include station 16748, leaving the other two near-dam stations to represent AU 1 since their data appears less-influenced by the cove limnology.

The upstream end of the reservoir receives the inflow of King’s Creek from the northwest

and Cedar Creek from the northeast. As noted earlier, the Cedar Creek arm is not listed for pH. King’s Creek carries the discharge of WWTFs in Terrell and Kauffman. These facilities, though relatively large, are a lengthy distance from the reservoir and their influence is probably attenuated by King’s Creek to a significant degree. A more likely source of enrichment is derived from the crops and pasture that dominate the northern half of the watershed. The upper reaches of the reservoir itself are a protected bird sanctuary and migratory bird populations could provide seasonal, localized pulses of phosphorus and nitrogen.

The pH exceedances appear to be a response to seasonally high primary productivity in

Cedar Creek reservoir, which in turn appears most likely caused by cultural eutrophication. The TMDL process is an appropriate means to address the high pH exceedances that are a secondary response to cultural eutrophication. 4.10 Segment 1212—Lake Somerville Lake Somerville, an impoundment of the Yegua Creek watershed in the Brazos River basin, was dammed in 1967 for flood control, conservation, and other uses. It covers 4,638 ha and depths range from 2 m (shallow upstream reaches) to 9 m (near the dam). Oil and gas operations are active in the watershed and numerous trails, parks, campgrounds, and marinas are established around the immediate vicinity of the lake. The City of Somerville sits on the northeast corner of the lake with a WWTF outfall in a tributary downstream of the dam. Vegetation in the region is primarily hardwood (post-oak) forests, rangeland and pasture. Soils are somewhat less leached than those of far-east Texas, but have a similar sandy-loam texture and are slightly to moderately acidic with low alkalinity (TAMU-SCL 2006). The region receives approximately 914 mm – 1041 mm of precipitation per year, with typically highest rainfall in May and Oct. The driest months are July and August.


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4.10.1 Historical Data Review TCEQ’s assessment data of Lake Somerville pH included 24-hr maximum and minimum

values, an approach that diverges from the protocols used in the other nine segments in this study where it does not appear that 24-hr pH data were included in the assessment process. All of the exceedances were from high pH values and occurred in summer months, June – August, when primary productivity is at its peak (Figure 4-23). Only two of the three stations in the listed AUs actually recorded pH exceedances: station 11881 in AU 1 (near-dam) and station 16879 in AU 3 (mid-lake), (Figure 4-24). Station 11885 is in a cove on the north shore, east of station 16879, and was sampled monthly from April 1999 – March 2000 with no exceedances. Across all sites and dates, only one of the samples in exceedance of the pH criteria was taken in the morning. Fourteen of 15 exceedances occurred in the afternoon.

TCEQ classified Lake Somerville as hypereutrophic (TCEQ 2008c). TCEQ ranked Lake

Somerville 98th in the TSI and noted that CHLA values are still trending upward. Based on phytoplankton data from Roelke et al. (2004), spikes in pH above criteria (9.0) as well as pH dips below 8.5 corresponded with algal biomass spikes and dips (see July 1999, July-August 2000, and February – August 2001 for examples; Figure 4-24). pH was also strongly correlated with DO%sat (r = 0.76, p <0.0001) and never exceeded 9.0 except during summer afternoons when primary production usually peaks. This analysis indicates that pH exceedances are primarily a response to algal blooms that occur on a nearly annual basis.

4.10.2 Potential Sources of pH Impairment and Recommendations High primary productivity in the lake is very likely the cause of the pH exceedances, but the cause of the lake’s hypereutrophy is unknown. Surprisingly, none of the four AUs on the lake were identified as having concerns for nutrients, though there were a handful of phosphate phosphorus samples that exceeded screening levels. Although the phytoplankton and algae in Lake Somerville are apparently maximizing available nutrients, the sources of nutrients to the lake cannot be determined at this time. There are no permitted dischargers in the immediate vicinity of the lake, except the City of Somerville WWTF, which discharges well below the dam. The ALCOA plant in Rockdale is situated about 50 km upstream of Lake Somerville and discharges into East and Middle Yegua Creeks. From 2002 – 2004 ALCOA outfalls combined for an average daily discharge of over 72 MGD. According to the BRA (personal communication, October, 2008) many years of testing upstream and downstream of ALCOA in East and Middle Yegua Creeks indicates that ALCOA discharges actually improved water quality in those tributaries. Therefore it is unlikely that ALCOA operations are exacerbating pH exceedances in Lake Somerville.

The high pH exceedances in Lake Somerville are most likely linked to the hypereutrophy of the reservoir. The sources of nutrients for this eutrophication are not clearly apparent from the data readily available for this study. The TMDL process is designed to address the nutrient input issues that appear to be driving pH exceedances, even if this “desktop” study could not determine conclusively point or nonpoint sources contributing to the hypereutrophic status of Lake Somerville.


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AU 1 11881 AU 3 11885 16879


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Figure 4-24 Map of Lake Somerville (Segment 1212).


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Summary of Factors Contributing to pH Excursions in Texas pH Evaluation Project Listed Texas Water Bodies and Recommended Actions

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SECTION 5

SUMMARY OF FACTORS CONTRIBUTING TO pH EXCURSIONS IN LISTED TEXAS WATER BODIES AND RECOMMENDED ACTIONS

Fluctuations in pH are ultimately an intrinsic quality of most reservoirs and streams,

including those in this study. If primary production outpaces respiration, there is a net loss of CO2 through photosynthetic assimilation and pH increases. If respiration processes dominate, CO2 is replaced faster than primary producers can assimilate it and pH drops. Problems arise when pH peaks and valleys become exaggerated during times of high abundance of producers and microbes and by naturally low alkalinity concentrations that limit the buffering capacity of the water body. Natural upsets in the production-respiration balance do occur, but cultural eutrophication increases the frequency and magnitude of the upsets. Annual summer algal blooms resulting in pH exceedances and poor water quality caused primarily by cultural eutrophication occur in many reservoirs throughout the State.

Through the analysis of data and information from this “desktop” study, it appeared that

the pH exceedances resulting in the 303(d) listing of the ten study segments fell into two broad categories. Category one were those water bodies in a climatic and geologic setting predisposed to naturally have pH exceedances, and category two were those water bodies where nutrient enrichment from anthropogenic point and nonpoint sources resulted in seasonally high primary productivity that in turn resulted in elevated pH values due to uptake of CO2. The recommended actions for the ten segments are provided in Table 5-1 and additional elaboration is provided immediately below.

In the Texas Panhandle alkalinity is very high and primary producers are subjected to

high levels of sun exposure. Thus pH levels are maintained over 8.0 throughout the year. In addition, high sodium content in the geology enables high accumulation of carbonate during seasons of peak productivity which leads to pH spikes well above the 9.0 criteria. Cultural eutrophication exacerbates the alkaline and saline condition of Texas Panhandle surface waters by nurturing high amounts of primary producers through nutrient enrichment. The morphology and management of Rita Blanca Lake would cause rapid eutrophication in any watershed, but in Northwest Texas there is little in the natural environment to curb the high pH spikes. The lone station used for assessment in Upper Prairie Dog Town Fork Red River is situated immediately below a reservoir where cultural eutrophication causes phytoplankton blooms and the underlying geology of the station and low canopy cover lend additional support for high pH exceedances as the data show.

In East Texas alkalinity is very low, precipitation is acidic, soils are acidic, and stream

canopy cover is usually dense. These factors contribute greatly to the low-pH of the upper portion of Caddo Lake, Big Cypress Creek below Lake of the Pines, and the Neches River above Lake Palestine. Low-end exceedances are not infrequent in this region, and are even to be expected. In these cases, the current minimum criterion of 6.0 may be high if maintenance of natural conditions is the end point. Alternatively, since exceedances are associated with winter months when groundwater flows more freely and instream leaf litter decomposition is

Summary of Factors Contributing to pH Excursions in Texas pH Evaluation Project Listed Texas Water Bodies and Recommended Actions

5-2

maximized, seasonal relaxation of criteria may be an option. All three of these classified segments that periodically experience low pH and for which re-evaluation of the minimum pH criterion is recommended could be amenable to further investigation through strategic location of continuous monitoring stations.

The segments of greatest concern are those listed for high pH despite their location in

ecoregions with naturally low soil pH and surface water alkalinity. This group of segments includes Lake Tawakoni, Lake Livingston, Cedar Creek Reservoir, and Lake Somerville. Phytoplankton production is causing pH exceedances in this group as evidenced by the summer seasonality of the exceedances, the significant correlation between pH and DO%sat, and other factors unique to each reservoir. Nonpoint sources are the most likely contributors of nutrient enrichment in these reservoirs. Point source influence varied among the reservoirs but generally impacted phytoplankton growth in localized patches (e.g. impairment in coves of Cedar Creek Reservoir). Table 5-1 Summary of Recommendations for pH Impaired Segments Included in the

Study.

Name Segment/ Assessment units

Suspect cause of pH exceedances

Recommended Actions

Rita Blanca Lake 0105_01 Cultural eutrophication & natural conditions

TMDL process or other watershed-based approach (watershed protection plan) §

Upper Prairie Dog Town Fork Red River

0229_02 Unrepresentative station location

Consider additional monitoring station locations and more data collection

Caddo Lake 0401_02, 03, 05 Natural conditions Review of standards (low pH criterion re-evaluation)

Big Cypress Creek below Lake O’ the Pines

0402_02, 03, 05 Natural conditions Review of standards (low pH criterion re-evaluation)

Lake Tawakoni 0507_04 Cultural eutrophication

TMDL process or other watershed-based approach (watershed protection plan)

Lake Palestine 0605_03, 09, 10 Cultural eutrophication


Neches River above Lake Palestine

0606_02, 03 Natural conditions Review of standards (low pH criterion re-evaluation)

Lake Livingston 0803_01, 06 Cultural eutrophication


Cedar Creek Reservoir

0818_01, 02, 03, 04, 05, 06, 07, 08, 09, 11, 12

Cultural eutrophication


Lake Somerville 121_01, 03 Cultural eutrophication


§ While Rita Blanca Lake is experiencing hypereutrophication as a result of cultural eutrophication processes, the geology, morphology, climate, and the use of the lake as migratory waterfowl habitat predisposes the lake to conditions that naturally favor high pH exceedances. Hence, the recommendation for a TMDL must be tempered by these confounding factors.

Texas pH Evaluation Project References

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SECTION 6

REFERENCES

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Benke, A. C., T.C. Van Arsdall, Jr., and D.M. Gillespie. 1984. Invertebrate productivity in a

subtropical blackwater river: the importance of habitat and life history. Ecological Monographs 54: 25-63.

Berner International Corporation. 2008. <http://www.berner.com/sales/energy_windspeed.html>.

Accessed 20 August 2008. Boyd, C. E. 1990. Water quality in ponds for aquaculture. Alabama Agricultural Experiment

Station, Auburn University. Birmingham Publishing Company, Birmingham, Alabama. Cain, Stanley A. 1928. Plant succession and ecological history of a central Indiana swamp.

Botanical Gazette 86: 384-401. CCWP (Cedar Creek Watershed Partnership). 2008. Cedar Creek watershed protection plan.

<http://nctx-water.tamu.edu/docs/2008-06-19/CedarCreekWPP.pdf>. Accessed 04 August 2008.

Cole, G. A. 1994. Textbook of limnology. 4th ed. Waveland Press, Inc., Prospect Heights, Ill. Crowe, A. L. 2008. An east Texas riddle--or what the old folks have always known. The water

monitor 1:1. Texas Commission on Environmental Quality. Crowe, A. L. 2007. Lake Palestine diurnal survey, October 2005 – 2006. Field Operations

Division—Region 5 Tyler, Texas Commission on Environmental Quality. Tyler, Texas. Crowe, A. L., M. Prater, and R. E. Cook. 2007. Acid rain potential in east Texas reservoirs. AS-

198. Field Operations Division—Region 5 Tyler, Texas Commission on Environmental Quality. Tyler, Texas.

Darville, R., D.K. Shellman, Jr., and R. Darville. 1998. Intensive water quality monitoring at

Caddo Lake, a ramsar wetland in Texas and Louisiana, USA. Caddo Lake Institute, Aspen, Colorado and Austin, Texas. Conference Paper Team Wetlands, Arlington, Virginia. 15-17 April 1998.

Dodds, W. K. 2002. Freshwater ecology: concepts and environmental applications. Academic

Press, San Diego. Dodds, W. K. 2006. Eutrophication and trophic state in rivers and streams. Limnology and

Oceanography 51: 671-680.


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Gibbs, R. J. 1970. Mechanisms controlling world water chemistry. Science 170: 1088-1090. Griffith, G. E., S. A. Bryce, J. M. Omernik, J. A. Comstock, A. C. Rogers, B. Harrison, S. L.

Hatch, and D. Bezanson. 2004. Ecoregions of Texas (color poster with map, descriptive text, and photography). USGS (map scale 1:2,500,000), Reston, VA.

Ground, T. A., and A. W. Groeger. 1994. Chemical classification and trophic characteristics of

Texas reservoirs. Lake and Reservoir Management 10: 189-201. Gustavson, T. C., W. W. Simpkins, A. Alhades, and A. Hoadley. 1982. Evaporite dissolution and

development of karst features on the rolling plains of the Texas Panhandle. Earth Surface Processes and Landforms 7: 545-563.

Lester, G. D., S.G. Sorensen, P.L. Faulkner, C.S. Reid, and I.E., Maxit. 2005. Louisiana

comprehensive wildlife conservation strategy. Louisiana Department of Wildlife and Fisheries. Baton Rouge, LA.

McFarland, A., and L. Hauck. 1999. Existing nutrient sources and contributions to the Bosque

River Watershed. PR9911. Texas Institute for Applied Environmental Research. Stephenville, TX.

McFarland, A., R. Kiesling, C. Pearson. 2001. Characterization of a Central Texas reservoir with

emphasis on factors influencing algal growth. TR0104. Texas Institute for Applied Environmental Research. Stephenville, TX.

NADP (National Atmospheric Deposition Program/National Trends Network). 2008.

<http://nadp.sws.uiuc.edu.>. Accessed 11 August 2008. NCTCOG (North Central Texas Council of Governments). 2003. North central Texas 2030

demographic forecast. North Central Texas Council of Governments Research and Information Services. Arlington, TX.

NOAA (National Oceanic and Atmospheric Administration). 2002. Climatography of the United

States No. 81 Supplement No. 1: monthly precipitation probabilities and quintiles 1971 – 2000. NOAA, National Environmental Satellite, Data, and Information Service, National Climatic Data Center. Asheville, NC.

NETMWD (Northeast Texas Municipal Water District). 2005. Basin highlights report 2005.

Hughes Springs, TX. Roelke, D., Y. Buyukates, M. Williams, and J. Jean. 2004. Interannual variability in the seasonal

plankton succession of a shallow, warm-water lake. Hydrobiologia 513: 205-218. RRA (Red River Authority of Texas). 2008. Canadian River Basin highlights report: 2008. Red

River Authority of Texas. Wichita Falls, TX.


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RRA. 2007. Red River Basin highlights report: 2007. Red River Authority of Texas. Wichita Falls, TX.

Skousen, J. G., C. A. Call, and R. W. Knight. 1990. Natural revegetation of an unreclaimed lignite surface mine in east-central Texas. The Southwestern Naturalist 35: 434-440.

Smith, V. H., S. B. Joye, and R. W. Howarth. 2006. Eutrophication of freshwater and marine

ecosystems. Limnology and Oceanography 51: 351-355. SRA (Sabine River Authority of Texas). 1999. Cowleech Fork special study—subwatershed

7.07. <http://www.sratx.org/srwmp/tcrp/state_of_the_basin/special_studies_on_priority_ watersheds/1999/Subwatershed7_07/default.asp>. Accessed 05 August 2008.

Stumm, W., and Morgan, J.J. 1996. Aquatic Chemistry. 3rd ed. John Wiley and Sons, Inc. New

York. TAMU-SCL (Texas A&M University-Soil Characterization Laboratory). 2006.

http://soildata.tamu.edu/. Accessed 29 July 2008. TCEQ (Texas Commission on Environmental Quality). 2008a. Draft 2008 Guidance for

Assessing and Reporting Surface Water Quality in Texas (March 19, 2008). TCEQ, Austin, TX.

TCEQ. 2008b. Draft 2008 Texas 303(d) list (March 19, 2008). TCEQ, Austin, TX. TCEQ. 2008c. Trophic Classification of Texas Reservoirs: 2008 Texas water quality inventory

and 303(d) list. TCEQ, Austin, TX. TCEQ. 2008d. Draft 2008 Texas Water Quality Inventory Water Bodies Evaluated (March, 19,

2008). TCEQ, Austin, TX. TNRCC (Texas Natural Resource Conservation Commission). 2000a. Texas Surface Water

Quality Standards. §307.1-307.10. Adopted by the Commission: July 26, 2000; Effective August 17, 2000 as the state rule. Austin, Texas.

TNRCC. 2000b. Texas water quality inventory 2000: Volume 2: Basins 1-11: narrative basin

summaries, basin maps, graphical basin summaries, and water body fact sheets. SFR-050/00. TCEQ, Austin, TX.

TPWD (Texas Parks and Wildlife Service). 2008. <http://www.tpwd.state.tx.us/spdest/findadest/

parks/caddo_lake>. accessed 22 July 2008. TRA (Trinity River Authority). 2008. Trinity River Authority 2008 basin highlights report.

Trinity River Authority. Arlington, TX. TRWD (Tarrant Regional Water District). 2008.

<http://www.twrd.com/prod/Lakes_CedarCreek.asp>. Accessed 02 August 2008.


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TWDB (Texas Water Development Board). 2007. Water for Texas. Texas Water Development

Board, Austin, Texas. TWDB. 2003. Volumetric survey of Lake Tawakoni. Texas Water Development Board,

Hydrographic Survey Group. Austin, TX. USACE (U.S. Army Corps of Engineers). <http://www.mvk.usace.army.mil/lakes/caddolake/

main.php?page=mainContent>. Accessed 21 July 2008. U.S. Census Bureau. 2000. <http://www.census.gov/>. Accessed 05 August 2008. USEPA (U.S. Environmental Protection Agency). 1991. Guidance for water quality-based

decisions: the TMDL process. Office of Water, USEPA 440/4-91-001. Wetzel, R. G. 2001. Limnology: lake and river ecosystems. 3rd ed. Academic Press, San Diego.

Texas pH Evaluation Project Appendix A

A-1

APPENDIX A

CORRELATIONS OF SELECTED ANALYTES FROM IMPAIRED SEGMENTS


A-2


A-3

Pearson correlation coefficients (r) were calculated by combining data from impaired stations in each segment and taking the means of the selected analytes including pH (median), alkalinity (Alk, mg/L as CaCO3), DO (mg/L), specific conductance (SpCond, μmhos/cm), total nitrate nitrogen (NO3, mg/L), secchi depth (Secchi, m), CHLA (μg/L), and the sample end time (EndTime). One asterisk indicates p < 0.05; two asterisks indicate p < 0.01. A “--” indicates insufficient data. Table A-1. Rita Blanca Lake (Segment 0105).

Table A-2. Upper Prairie Dog Town Fork Red River (Segment 0229).

Table A-3. Caddo Lake (Segment 0401).

pH Alk DO SpCond NO3 Secchi CHLApHAlk -0.40DO -0.05 -0.10SpCond 0.21 0.44 -0.04NO3 -0.48 -0.23 0.64 -0.48Secchi -0.01 0.25 0.18 -0.10 0.56CHLA 0.44 -0.34 -0.05 -0.21 -0.37 -0.16EndTime -0.37 0.43 0.08 0.10 0.32 0.23 -0.69**

pH Alk DO SpCond NO3 Secchi CHLApHAlk -0.52DO -0.46 -0.27SpCond 0.36 -0.11 -0.32NO3 0.14 0.19 0.51 0.21Secchi -0.54 -0.003 0.45 -0.28 -0.59CHLA -0.54 0.17 0.78* -0.39 0.55 0.36EndTime 0.19 0.34 -0.46 0.34 0.02 -0.26 -0.34

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.58**DO 0.07 -0.27SpCond 0.13** 0.52* -0.25**NO3 -- -- -- --Secchi -0.02 -0.02 0.40** -0.34** --CHLA 0.29 0.14 -0.27 -0.10 -- -0.38EndTime 0.06 -0.09 0.22** 0.03 -- 0.05 -0.13


A-4

Table A-4. Big Cypress Creek (Segment 0402).

Table A-5. Lake Tawakoni (Segment 0507).

Table A-6. Lake Palestine (Segment 0605).

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.58**DO -0.05 -0.19SpCond 0.34** 0.46** -0.07NO3 -0.27 -0.20 -0.34 -0.16Secchi 0.16 0.02 0.26** 0.30* 0.05*CHLA 0.02 0.53** -0.53** 0.16 -0.30 -0.14EndTime 0.004** 0.20 -0.14 0.002 0.24 -0.19* 0.01

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.38**DO -0.29** -0.30*SpCond 0.2* 0.70** -0.08NO3 -0.74** -0.44** 0.61** -0.11Secchi 0.23* -0.11 -0.01 0.04 -0.17CHLA 0.69** 0.35* 0.02 0.13 -0.45* -0.08EndTime 0.24** 0.23 0.05 0.38** -0.32* -0.004 0.31*

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.71**DO 0.24 -0.08SpCond 0.38** 0.68** -0.11NO3 -- -- -- --Secchi -0.02 -0.18 0.10 -0.31* --CHLA 0.61** 0.69** -0.01 0.41** -- -0.10EndTime 0.35** 0.16 0.25 0.08 -- -0.04 0.26


A-5

Table A-7. Neches River above Lake Palestine (Segment 0606).

Table A-8. Lake Livingston (Segment 0803).

Table A-9. Cedar Creek Reservoir (Segment 0818).

Table A-10. Lake Somerville (Segment 1212)

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.54**DO -0.01 -0.78**SpCond -0.68** 0.05 -0.08NO3 0.31 -0.30 -0.07 -0.75Secchi -0.26 -0.54** 0.59** 0.21 0.59**CHLA 0.07 0.38** -0.46** 0.18 -0.46** 0.27EndTime 0.43** 0.49** -0.25 -0.15 -0.25 -0.22 0.33*

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.39*DO 0.14 -0.03SpCond 0.21 0.75 -0.01NO3 -0.58** -0.38* -0.02 -0.16Secchi 0.26** 0.22 0.003 -0.70** -0.53CHLA 0.54** 0.44** 0.06 -- -0.59** 0.14EndTime 0.39** 0.001 0.19* 0.02 -0.30 -0.11 0.11

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.41**DO 0.02 -0.19**SpCond 0.14** 0.70** 0.03NO3 -0.25 -0.07 -0.01 0.06Secchi 0.09 0.15 -0.19** -0.08 -0.18CHLA 0.40** 0.55** -0.13* 0.22** -0.05 -0.15**EndTime 0.002 -0.001 0.16** 0.08 -0.11 -0.06 -0.12*

pH Alk DO SpCond NO3 Secchi CHLApHAlk 0.03DO 0.48** -0.18SpCond 0.31** 0.86** 0.18NO3 -0.22 0.57 -0.20 -0.21Secchi -0.37** -0.61* -0.12 -0.30** 0.17CHLA 0.07 0.48* -0.09 0.45* 0.68 -0.34EndTime 0.40** 0.46* 0.03 0.15 0.15 -0.19 0.32


A-6

texas ph evaluation project - tiaertiaer.tarleton.edu/pdf/pr0810.pdf · texas ph evaluation project...

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