total maximum daily load (tmdl) - dnr · completed: feb. 8, 2017 approved: mussel fork e. coli tmdl...

HUC 10280202 – Lower Chariton Subbasin

Water body ID#: 0674

Pollutant(s): Pathogens as indicated by Escherichia coli

Prepared by: Watershed Protection Section

Total Maximum Daily Load (TMDL)

for

Mussel Fork Adair, Linn, Macon and Sullivan counties

Pollutants of concern: Pathogens

Completed: Feb. 8, 2017

Approved:

Mussel Fork E. coli TMDL - Missouri

i

WATER BODY SUMMARY

Mussel Fork – Water body ID No. 0674

Pollutant(s): Pathogens as indicated by E. coli

Name: Mussel Fork

Location: Adair, Linn, Macon and Sullivan counties

Hydrologic Unit Codes (HUC):1

8-digit HUC (subbasin):

10280202 – Lower Chariton

12-digit HUCs (subwatersheds):

102802020301 – Headwaters Mussel Fork

102802020302 – Little Mussel Creek-Mussel Fork

102802020303 – Painter Creek-Mussel Fork

Water Body Identification Number (WBID)

and Hydrologic Class:2

WBID 0674 – Class C

Designated Uses:3

Protection and propagation of fish, shellfish and wildlife – warm water habitat

Whole body contact recreation category B

Livestock and wildlife protection

Secondary contact recreation

Human health protection

Drinking water supply

Irrigation

Impaired Uses:



Pollutant Identified on the 303(d) List: Escherichia coli, or E. coli (fecal indicator bacteria)

Length and Location of Impaired Segment: 46.7 kilometer (29 miles), from Sec. 18, T58N, R17W to Sec. 2, T62N, R18W

1 Watersheds are delineated by the USGS using a nationwide system based on surface hydrologic features. This system divides

the country into 2,270 8-digit hydrologic units (USGS and NRCS 2013). A hydrologic unit is a drainage area delineated to nest in

a multilevel, hierarchical drainage system. A hydrologic unit code is the numerical identifier of a specific hydrologic unit

consisting of a 2-digit sequence for each specific level within the delineation hierarchy (FGDC 2003). 2 For hydrologic classes see 10 CSR 20-7.031(1)(F). Class C streams may cease to flow during dry periods, but maintain

permanent pools that support aquatic life. 3 For designated uses see 10 CSR 20-7.031(1)(C) and 10 CSR 20-7.031 Table H. Presumed uses are assigned per

10 CSR 20-7.031(2)(A) and (B) and are reflected in the Missouri Use Designation Dataset described at 10 CSR 20-7.031(2)(E).

Location of the Mussel Fork watershed


ii

TABLE OF CONTENTS

1. Introduction ............................................................................................................................................... 1

2. Watershed Description ............................................................................................................................. 1

2.1 Geology, Physiography and Soils ....................................................................................................... 3

2.2 Rainfall and Climate ............................................................................................................................ 5

2.3 Population ............................................................................................................................................ 7

2.4 Land Cover .......................................................................................................................................... 7

3. Applicable Water Quality Standards ......................................................................................................... 9

3.1 Designated Uses .................................................................................................................................. 9

3.2 Water Quality Criteria ......................................................................................................................... 9

3.3 Antidegradation Policy ...................................................................................................................... 10

4. Defining the Problem .............................................................................................................................. 10

5. Source Inventory and Assessment .......................................................................................................... 12

5.1 Point Sources ..................................................................................................................................... 12

5.1.1 Municipal and Domestic Wastewater Discharge Permits ........................................................... 14

5.1.2 Concentrated Animal Feeding Operations (CAFOs) .................................................................. 15

5.1.3 General Wastewater and Stormwater Permits ............................................................................ 16

5.1.4 Illicit Straight Pipe Discharges ................................................................................................... 16

5.2 Nonpoint Sources .............................................................................................................................. 16

5.2.1 Agricultural Runoff .................................................................................................................... 17

5.2.2 Urban Stormwater Runoff .......................................................................................................... 18

5.2.3 Onsite Wastewater Treatment Systems ...................................................................................... 19

5.2.4 Natural Background Contributions ............................................................................................. 20

5.2.5 Riparian Corridor Conditions ..................................................................................................... 20

6. Numeric TMDL Target and Modeling Approach ................................................................................... 21

7. Calculating Loading Capacity ................................................................................................................. 22

8. Wasteload Allocation (Allowable Point Source Load) ........................................................................... 24

8.1 Municipal and Private Domestic Wastewater Discharges ................................................................. 24

8.2 CAFOs ............................................................................................................................................... 25

8.3 General Wastewater and Stormwater Permits ................................................................................... 25

8.4 Illicit Straight Pipe Discharges .......................................................................................................... 25

8.5 Considerations for Future Sources .................................................................................................... 25

9. Load Allocation (Nonpoint Source Load) .............................................................................................. 26

10. Margin of Safety ................................................................................................................................... 26

11. Seasonal Variation ................................................................................................................................ 27

12. Monitoring Plans ................................................................................................................................... 27

13. Reasonable Assurance .......................................................................................................................... 27

14. Public Participation ............................................................................................................................... 28

15. Administrative Record and Supporting Documentation ....................................................................... 29

16. References ............................................................................................................................................. 29


iii

LIST OF TABLES

Table 1. Hydrologic soil groups in the Mussel Fork watershed ................................................................... 3

Table 2. 30-year monthly climate normals ................................................................................................... 5

Table 3. Land cover in the Mussel Fork watershed ...................................................................................... 7

Table 4. Summary of recreational season E. coli data in Mussel Fork, WBID 0674 ................................. 11

Table 5. Municipal wastewater lagoons in the Mussel Fork watershed...................................................... 14

Table 6. CAFOs in the Mussel Fork watershed .......................................................................................... 15

Table 7. Cattle population estimates for pasture areas in the Mussel Fork, WBID 0674, watershed ......... 18

Table 8. Numbers of other livestock by county .......................................................................................... 18

Table 9. Estimated numbers of septic systems in the Mussel Fork watershed ........................................... 19

Table 10. Land cover in the riparian corridors of the Mussel Fork, WBID 0674, watershed ..................... 20

Table 11. TMDL and allocation values for Mussel Fork, WBID 0674, at selected flows .......................... 23

Table 12. Wasteload allocations for municipal wastewater dischargers ..................................................... 24

LIST OF FIGURES

Figure 1. Mussel Fork, WBID 0674, watershed ........................................................................................... 2

Figure 2. Hydrologic soil groups in the Mussel Fork, WBID 0674, watershed............................................ 5

Figure 3. Monthly minimum and maximum temperature normals ............................................................... 6

Figure 4. Monthly precipitation normals ...................................................................................................... 6

Figure 5. Distribution of land cover in the Mussel Fork, WBID 0674, watershed ....................................... 8

Figure 6. Monthly recreational season E. coli data from Mussel Fork ....................................................... 11

Figure 7. Permitted features in the Mussel Fork, WBID 0674, watershed ................................................. 13

Figure 8. Mussel Fork, WBID 0674, load duration curve .......................................................................... 23

LIST OF APPENDICES

Appendix A: Mussel Fork recreational season E. coli data ........................................................................ 32

Appendix B: Development of the Mussel Fork Bacteria Load Duration Curve ......................................... 33

Appendix C: Summary of Wasteload Allocations ...................................................................................... 35


1

1. Introduction

The Department of Natural Resources in accordance with Section 303(d) of the federal Clean Water

Act is establishing this Mussel Fork total maximum daily load, or TMDL. This TMDL report

addresses a 29 mile segment of Mussel Fork that was approved by the U.S. Environmental Protection

Agency for inclusion on Missouri’s 2016 303(d) List on July 12, 2016.4 This stream segment has

been determined to be impaired by disease causing pathogens as indicated by the presence of

Escherichia coli, or E. coli, bacteria, which are present at concentrations that exceed Missouri’s

water quality criteria for this pollutant. This report addresses the pathogen impairment of Mussel

Fork by establishing a TMDL for E. coli.

Section 303(d) of the federal Clean Water Act and Chapter 40 of the Code of Federal Regulations

(CFR) Part 130 requires states to develop TMDLs for waters not meeting water quality standards.

The TMDL process quantitatively assesses the impairment factors so that states can establish water

quality-based controls to reduce pollution and restore and protect the quality of their water resources.

The purpose of a TMDL is to determine the pollutant loading a water body can assimilate without

exceeding state water quality standards. Missouri’s Water Quality Standards at 10 CSR 20-7.031

consist of three major components: designated uses, water quality criteria to protect those uses and an

antidegradation policy. A TMDL establishes the pollutant loading capacity necessary to attain the

water quality standards established for each water body based on the relationship between pollutant

sources and instream water quality conditions. A TMDL consists of a wasteload allocation, a load

allocation, and a margin of safety. The wasteload allocation is the fraction of the total pollutant load

apportioned to point sources. The load allocation is the fraction of the total pollutant load apportioned

to nonpoint sources. The margin of safety is a percentage of the TMDL that accounts for any

uncertainty associated with the model assumptions as well as any data inadequacies.

In addition to E. coli, Mussel Fork is also impaired due to excess sediment. To address this

impairment, the U.S. Environmental Protection Agency established a TMDL on Sept. 25, 2006 with

targets for total suspended solids. This previously developed TMDL is available online at

dnr.mo.gov/env/wpp/tmdl/0674-mussel-fk-ck-record.htm.

2. Watershed Description

Mussel Fork is a 169 kilometer (105 mile) tributary to the Chariton River and is divided in

Missouri’s Water Quality Standards as two separate water body segments. The first 93.3 km (58 mi)

of Mussel Fork that extends upstream from the confluence with the Chariton River is identified as

water body identification number 0670. Upstream of this segment for approximately 46.7 km (29 mi)

is the impaired water body segment addressed by this TMDL report, water body ID number 0674.

The area draining to this impaired segment is approximately 326.5 square kilometers (126 square

miles). This watershed area is mostly rural and accounts for approximately 37 percent of the entire

Mussel Fork watershed and only 5.3 percent of the entire Chariton River basin. Municipal areas

make up only 3.1 km2 (1.2 mi

2) of the impaired watershed’s area and include portions of Green City,

Greencastle and Winigan. The impaired Mussel Fork watershed includes portions of four counties;

Adair, Linn, Macon and Sullivan (Figure 1).

4 Missouri’s current and past 303(d) lists of impaired waters can be found online on the department’s website at

dnr.mo.gov/env/wpp/waterquality/303d/303d.htm.

http://dnr.mo.gov/env/wpp/tmdl/0674-mussel-fk-ck-record.htm

http://dnr.mo.gov/env/wpp/waterquality/303d/303d.htm


2

Figure 1. Mussel Fork, WBID 0674, watershed


3

2.1 Geology, Physiography and Soils

The Mussel Fork watershed is located within the Grand/Chariton ecological drainage unit (MoRAP

2005). Ecological drainage units are groups of watersheds that have similar biota, geography, and

climate characteristics (USGS 2009). The characteristics of an ecological drainage unit are varied and

are partially based on the ecoregions they contain. Ecoregions are areas with similar ecosystems and

environmental resources.5 A level I ecoregion is a coarse, broad category, while a level IV is a more

defined grouping. The Mussel Fork watershed is entirely contained within the Loess Flats and Till

Plains level IV ecoregion. In general, this ecoregion is characterized as being primarily cropland and

having gentle slopes with deep to moderate loess deposits over glacial till. However, the portion of

the ecoregion where this water body is located is described as having more hills, lacking glacial till,

and having more woody vegetation along stream corridors than what is typical in other portions of

the ecoregion (Chapman, et al. 2002).

Soils in the Mussel Fork watershed are varied, but can be grouped based on similar characteristics.

Table 1 provides a summary of the hydrologic soil groups found in the Mussel Fork watershed.

Hydrologic soil groups categorize soils by their runoff potential. A soil’s hydrologic soil group

relates to the rate at which water enters the soil profile under conditions of a bare soil surface and

being thoroughly wetted. Group A represents soils with the highest rate of infiltration and the lowest

runoff potential under these conditions and Group D represents the group with the lowest rate of

infiltration and highest potential for runoff (NRCS 2007). The dominant soil group in the Mussel

Fork watershed is Group D. Group D soils consist chiefly of clay soils, soils with a permanent high

water table, soils with a claypan or clay layer at or near the surface, and shallow soils over nearly

impervious material. The second most represented soil group is the dual group C/D. These soils share

the soil characteristics of Group C soils, sandy clay loam soils, but have a high water table as is

common of soils in Group D. Group B soils include silt loam and loam, which have moderate

infiltration rates. These characteristics are shared with soils of the dual group B/D, but soils in group

B/D also have a high water table. There are no Group A soils in the watershed. Group A soils are

typically comprised of sand or gravel and very little clay. Areas where soils were not rated are

primarily areas described in the soil survey as being open water. Figure 2 shows the distribution of

these hydrologic soil groups throughout the watershed. It should be noted, that hydrologic soil groups

are only one factor influencing runoff in the watershed. Impervious surfaces, vegetative cover and

land use can also influence the potential for runoff regardless of the soil types present in those areas.

Table 1. Hydrologic soil groups in the Mussel Fork watershed (NRCS 2011)

5 Ecoregion is defined in Missouri’s Water Quality Standards at 10 CSR 20-7.031 (1)(I).

Hydrologic Soil Group

Area

(km2)

Area

(mi2)

Area

(%)

Group B 14.32 5.53 4.38

Dual Group B/D 21.99 8.49 6.73

Group C 18.54 7.16 5.68

Dual Group C/D 84.28 32.54 25.81

Group D 187.05 72.22 57.28

Not Rated 0.39 0.15 0.12

Totals: 326.57 126.09 100.00


4

Figure 2. Hydrologic soil groups in the Mussel Fork, WBID 0674, watershed


5

2.2 Rainfall and Climate

Weather stations provide useful information for developing a general understanding of climatic

conditions in a watershed. The closest weather station to the Mussel Fork watershed is located

28 km (17 mi) to the east in Kirksville. This weather station records daily precipitation and

temperature data and is expected to be representative of climatic conditions in the Mussel Fork

watershed (Table 2). Precipitation is an important factor related to stream flow and stormwater runoff

events that can influence certain pollutant sources. On the next page, Figure 3 presents a summary of

the monthly temperature normals calculated for the 30-year period of 1981 through 2010 and Figure

4 depicts monthly precipitation normals for this same period.

Table 2. 30-year monthly climate normals from Kirksville Weather Station (NOAA 2014)

Month Total PPTN Normal

mm (in)

Mean Max Temp. Normal

ºC (ºF)

Mean Min Temp. Normal

ºC (ºF)

January 32.76 (1.29) 0.78 (33.4) -9.61 (14.7)

February 41.91 (1.65) 3.61 (38.5) -7.50 (18.5)

March 64.01 (2.52) 10.22 (50.4) -1.83 (28.7)

April 93.47 (3.68) 16.78 (62.2) 4.11 (39.4)

May 136.65 (5.38) 22.17 (71.9) 10.33 (50.6)

June 134.62 (5.30) 27.17 (80.9) 15.83 (60.5)

July 131.32 (5.17) 29.72 (85.5) 18.39 (65.1)

August 102.87 (4.05) 28.94 (84.1) 17.17 (62.9)

September 103.12 (4.06) 24.67 (76.4) 11.89 (53.4)

October 84.33 (3.32) 17.89 (64.2) 5.67 (42.2)

November 66.80 (2.63) 10.06 (50.1) -1.00 (30.2)

December 41.15 (1.62) 2.56 (36.6) -7.39 (18.7)

Total PPTN & Avg Temp: 1,033.02 (40.67) 16.21 (61.18) 4.67 (40.41)

Note: PPTN = precipitation; Temp. = temperature


6

Figure 3. Monthly minimum and maximum temperature normals

Figure 4. Monthly precipitation normals


7

2.3 Population

State and county population estimates are readily available from the U.S. Census Bureau’s 2010

census; however the population of the Mussel Fork watershed itself is not. An estimate of the

watershed’s population can be determined using U.S. Census Bureau census block data from 2010.

Using this data, the population of the Mussel Fork watershed is estimated to be 1,002 people. The

population of the watershed has changed little since 1990 when census data from that year showed

the watershed as having a population of 1,024 people. Approximately 54 percent of the population

(543 people) resides within municipal areas in the watershed, which is also relatively unchanged

from 1990 estimates. No parts of the municipalities in the watershed are contained within U.S.

Census Bureau defined urban areas, which would be subject to municipal separate storm sewer

system permit regulations.

These population estimates were completed using Geographic Information System, or GIS, software

and superimposing the watershed boundary over a map of census blocks. Wherever the centroid of a

census block fell within a watershed boundary, the entire population of the census block was

included in the total. If the centroid of the census block was outside the boundary, then the

population was excluded. Using a similar method, the population residing within municipal

boundaries was estimated by superimposing municipal areas over the map of census blocks.

2.4 Land Cover

Land cover calculations were made using the 2011 National Land Cover Database published by the

U.S. Geological Survey, or USGS (Homer et al. 2015). Land cover information is summarized in

Table 3. Figure 5 depicts the distribution of land coverages throughout the watershed.

As can be seen from this information, land coverages associated with agricultural activities dominate

the watershed and account for more than 62 percent of the watershed area. Of this, cropland only

accounts for approximately 5.6 percent of the watershed area and vegetated areas used for hay or

pasture make up nearly 57 percent of the watershed area. Forested areas also make up a large portion

of the watershed and account for more than a quarter of the total watershed area. Developed areas

make up only 4 percent of the watershed area and are primarily open spaces composed of lawn

grasses and having less than 20 percent imperviousness.

Table 3. Land Cover in the Mussel Fork watershed

Land Cover

Type Area

hectare (acre)

Area

km2 (mi

2)

Percent

Developed, High Intensity 0.81 (2.00) 0.01 (0.00) < 0.01

Developed, Medium Intensity 25.65 (63.38) 0.26 (0.10) 0.08

Developed, Low Intensity 140.13 (346.26) 1.40 (0.54) 0.43

Developed, Open Space 1,150.25 (2,842.33) 11.50 (4.44) 3.52

Cultivated Crops 1,829.19 (4,520.01) 18.29 (7.06) 5.60

Hay/Pasture 18,601.65 (45,965.60) 186.02 (71.82) 56.96

Forest 8,654.65 (21,386.06) 86.55 (33.42) 26.50

Shrub and Herbaceous 1,473.52 (3,641.14) 14.74 (5.69) 4.51

Wetlands 603.52 (1,491.33) 6.04 (2.33) 1.85

Open Water 175.23 (432.99) 1.75 (0.68) 0.54

Total: 32,654.60 (8,0691.10) 326.56 (126.08) 100.00


8

Figure 5. Distribution of land cover in the Mussel Fork, WBID 0674, watershed


9

3. Applicable Water Quality Standards

The purpose of developing a TMDL is to identify the pollutant loading that a water body can

assimilate and still attain and maintain water quality standards. Water quality standards are therefore

central to the TMDL development process. Under the federal Clean Water Act, every state must

adopt water quality standards to protect, maintain, and improve the quality of the nation’s surface

waters (U.S. Code Title 33, Chapter 26, Subchapter III). Water quality standards consist of three

major components: designated uses, water quality criteria to protect those uses, and an

antidegradation policy.

3.1 Designated Uses

Designated uses are the uses for a water body defined in the state Water Quality Standards at

10 CSR 20-7.031(1)(C) and assigned per 10 CSR 20-7.031(2) and Table H.6 These uses must be

maintained in accordance with the federal Clean Water Act. The following designated uses have been

assigned to WBID 0674 of Mussel Fork and are reflected in the Missouri Use Designation Dataset as

described at 10 CSR 20-7.031(2)E:7

Protection and propagation of fish, shellfish and wildlife – warm water habitat

Livestock and wildlife protection



Human health protection

Drinking water supply

Irrigation

The designated uses of Mussel Fork that are impaired due to high E. coli concentrations are whole

body contact recreation category B and secondary contact recreation. Whole body contact recreation

includes activities in which there is direct human contact with surface water that results in complete

body submergence, such as swimming. During such activities, accidental ingestion of the water may

occur and there is direct contact to sensitive body organs, such as the eyes, ears and nose. Category A

waters include water bodies that have been established by the property owner as public swimming

areas welcoming access by the public for swimming purposes and waters with documented existing

whole body contact recreation uses by the public (10 CSR 20-7.031(1)(C)2.A.(I)). Category B

applies to waters designated for whole body contact recreation, but are not contained within category

A (10 CSR 20-7.031(1)(C)2.A.(II)). Secondary contact recreation includes activities in which there is

limited, incidental or accidental contact with the water and the probability of ingesting appreciable

quantities of water is minimal. Such activities include boating, fishing and wading (10 CSR 20-

7.031(1)(C)2.B.).

3.2 Water Quality Criteria

Water quality criteria are limits on certain chemicals or conditions in a water body to protect

particular designated uses. Water quality criteria can be expressed as specific numeric criteria or as

general narrative statements. In Missouri’s Water Quality Standards at 10 CSR 20-7.031(5)(C) and

Table A, specific numeric bacteria criteria are given to protect whole body and secondary contact

6 The terminology used for naming designated uses varies from what is presented in the text of 10 CSR 20-7.031 and what is presented

in Table H. The terminology utilized in the text of the water quality standards rule is presented here. 7 The Missouri Use Designation Dataset documents the names and locations of the state’s rivers, streams, lakes and reservoirs, which

have been assigned designated uses (10 CSR 20-7.031 (1)(P)).


10

recreation during the recreational season, which is defined as being from April 1 through October 31.

For category B waters, the E. coli count during the recreational season shall not exceed a geometric

mean of 206/100 mL of water. To be protective of secondary contact recreation, the E. coli count

during the recreational season must not exceed a geometric mean of 1,134/100 mL. In addition to

these specific criteria, the general criteria at 10 CSR 20-7.031(4) are narrative statements that provide

aesthetic and acute toxicity protections for all waters of the state.

3.3 Antidegradation Policy

Missouri’s Water Quality Standards include the EPA “three-tiered” approach to antidegradation, and

may be found at 10 CSR 20-7.031(3).

Tier 1 – Protects public health, existing in-stream water uses and a level of water quality necessary to

maintain and protect those uses. Tier 1 provides the absolute floor of water quality for all

waters of the United States. Existing instream water uses are those uses that were attained on

or after Nov. 28, 1975, the date of EPA’s first Water Quality Standards Regulation.

Tier 2 – Protects and maintains the existing level of water quality where it is better than applicable

water quality criteria. Before water quality in Tier 2 waters can be lowered, there must be an

antidegradation review consisting of: (1) a finding that it is necessary to accommodate

important economic and social development in the area where the waters are located; (2) full

satisfaction of all intergovernmental coordination and public participation provisions; and (3)

assurance that the highest statutory and regulatory requirements for point sources and best

management practices for nonpoint sources are achieved. Furthermore, water quality may

not be lowered to less than the level necessary to fully protect the “fishable/swimmable” uses

and other existing uses.

Tier 3 – Protects the quality of outstanding national and state resource waters, such as waters of

national and state parks, wildlife refuges and waters of exceptional recreational or ecological

significance. There may be no new or increased discharges to these waters and no new or

increased discharges to tributaries of these waters that would result in lower water quality. Waters in which a pollutant is at, near or exceeds the water quality criteria are considered in Tier 1

status for that pollutant. Therefore, the antidegradation goal for the impaired segment of Mussel Fork

is to restore stream water quality to levels that meet water quality standards.

4. Defining the Problem

Missouri’s Water Quality Standards use E. coli, bacteria found in the intestines of humans and warm-

blooded animals, as indicators of potential fecal contamination and risk of pathogen-induced illness to

humans. The department judges a stream to be impaired if the water quality criteria are exceeded in

any of the last three years for which there is a minimum of five samples collected during the

recreational season. This approach is detailed in the department’s 2016 Listing Methodology

Document, which is available online at dnr.mo.gov/env/wpp/waterquality/303d/303d.htm.

E. coli data for Mussel Fork has been collected since 1998 and was first listed as impaired on

Missouri’s combined 2004/2006 303(d) List. Most recently, Mussel Fork was included on the 2016

303(d) List due to documented exceedances of the whole body contact category B criterion in 2011,

2013 and 2016. In 2011, the criterion for the protection of secondary contact recreation was also

http://dnr.mo.gov/env/wpp/waterquality/303d/303d.htm


11

exceeded. Per federal regulations at 40 CFR§130.7(c)(1), TMDLs are required for all waters included

on a state’s approved 303(d) list.

Available recreational season E. coli data collected from water body 0674 of Mussel Creek is

summarized in Table 4. Although older data is available, only recreational season E. coli data available

since 2010 are presented. Data collected during this more recent period are expected to be the most

representative of current conditions that may be contributing bacteria loads to Mussel Fork. This data

is further summarized in the box plot presented in Figures 6. Individual E. coli measurements used to

calculate the values in Table 4 and Figure 6 are presented in Appendix A. These observed data are

used in this TMDL for illustration purposes only and were not used in the calculation of TMDL targets

or allocations for Mussel Fork.

Table 4. Summary of recreational season E. coli data for Mussel Fork, WBID 0674

Year

No. of

samples

Minimum

(count/100mL)

Maximum

(count/100mL)

Geometric Mean

(count/100mL)

2010 7 130 7,100 656

2011 6 250 33,000 1,172

2012 3 48 900 294

2013 5 19 10,000 511

2014 7 190 1,400 450

Figure 6. Monthly recreational season E. coli data from Mussel Fork (2010 – 2014)


12

5. Source Inventory and Assessment

Various sources may be contributing bacteria loads in varying degrees to Mussel Fork. For this

reason, a source inventory and assessment is included in this TMDL to identify and characterize

known, suspected and potential sources of pollutant loading specific to the Mussel Fork watershed.

Sources identified in this report are categorized as being either point (regulated) or nonpoint

(unregulated) in nature.

5.1 Point Sources

Point sources are defined under Section 502(14) of the federal Clean Water Act and are typically

regulated through the Missouri State Operating Permit program.8 Point sources include any

discernible, confined and discrete conveyance, such as a pipe, ditch, channel, tunnel or conduit, by

which pollutants are transported to a water body. Under this definition, permitted point sources

include permitted municipal and domestic wastewater dischargers, site-specific permitted industrial

and non-domestic wastewater dischargers, concentrated animal feeding operations, municipal

separate storm sewer systems, and general wastewater and stormwater permitted entites. In addition

to these permitted sources, illicit straight pipe discharges, which are illegal and therefore

unpermitted, are also point sources. The locations of each permitted outfall are presented on the

following page in Figure 7.

At the time of this writing, the Mussel Fork watershed contained eight permitted facilities. Two of

these facilities are municipal wastewater facilities, five are concentrated animal feeding operations,

or CAFOs, and one holds a stormwater land disturbance permit.9 There are no permitted municipal

separate storm sewer systems or industrial and non-domestic wastewater dischargers in the

watershed. The locations of the permitted structures and outfalls for the facilities present in the

Mussel Fork watershed are presented in Figure 7. More detailed discussions regarding these facilities

and their potential bacteria contributions appear in the following subsections.

8 The Missouri State Operating Permit program administers the federal National Pollutant Discharge Elimination System, or NPDES,

program for Missouri. The NPDES program requires all point sources that discharge pollutants to waters of the United States to obtain

a permit. 9 Permit numbers for Missouri are accurate as of Feb. 23, 2016. Permits associated with stormwater from land disturbance activities are

temporary and the number of effective permits of this type in a watershed may vary in any given year. Despite this variability, TMDL

targets and allocations will not change as a result of any changes in the number of these types of permits.


13

Figure 7. Permitted features in the Mussel Fork, WBID 0674, watershed


14

5.1.1 Municipal and Domestic Wastewater Discharge Permits

Domestic wastewater dischargers include both publicly owned municipal wastewater treatment plants

and non-municipal treatment facilities. Domestic wastewater is primarily household waste, which

includes graywater and sewage. Untreated or inadequately treated discharges of domestic wastewater

can be significant sources of bacteria to receiving waters (EPA 1986). Influences of pollutant loading

from domestic dischargers are typically most evident at low-flow conditions when stormwater

influences are lower or nonexistent. Table 5 lists the two municipal wastewater lagoons located in the

Mussel Fork watershed along with their design flows as stated in Missouri State Operating Permits.10

Table 5. Municipal wastewater lagoons in the Mussel Fork watershed

Permit No.

Facility

Name

Receiving

Stream

Design Flow

m3/s (ft

3/s)

Permit

Expires11

(Mo/Day/Year)

MO-0103322

Greencastle Lagoon

System

An unnamed tributary to

Mussel Fork (WBID 3960) 0.001 (0.041) 03/31/2017

MO-0112135

Green City Wastewater

Treatment Facility

An unnamed tributary to

Mussel Fork (WBID 3960) 0.004 (0.155) 03/30/2017

These two domestic wastewater treatment facilities discharge treated wastewater into tributaries of

Mussel Fork, however neither one currently disinfects their effluent nor do their permits contain

effluent limits for E. coli. Due to a lack of E. coli monitoring data from either of these facilities, the

significance of any bacteria loading from these facilities cannot be determined. However, since

neither of these facilities disinfect their effluent, there is a potential for significant bacteria loading to

occur. It should be noted that historically these facilities had been exempted from bacteria

limitations and disinfection requirements due to conditions set forth in 10 CSR 20-7.015(9)(B)1.D.,

which only requires E. coli permit limitations if discharges are within two miles of a water

designated for whole body contact recreation. Since issuance of these facilities’ permits, water

quality standard revisions approved by EPA on Oct. 22, 2014, have expanded designations of whole

body contact recreation to streams in closer proximity to these facilities. Therefore, E. coli limits and

any applicable disinfection requirements will be included upon permit renewal. Such requirements

will maintain bacteria loads from these facilities to concentrations that meet water quality standards.

In addition to the direct discharges from these municipal wastewater treatment facilities, potential

bacteria contributions may also occur from overflows occurring from the adjoining sanitary sewer

system. A sanitary sewer system is a municipal wastewater collection system designed to convey

domestic, commercial and industrial wastewater to a municipal wastewater treatment facility. This

system can include limited amounts of inflow and infiltration from groundwater and stormwater, but

it is not designed to collect large amounts of runoff from precipitation events. Untreated or partially

treated discharge from a sanitary sewer system is referred to as a sanitary sewer overflow. Sanitary

sewer overflows can be caused by a variety of reasons including blockages, line breaks, sewer

defects, power failures and vandalism. Sanitary sewer overflows can occur during either dry or wet

weather and at any point in the collection system and can include overflows from manholes, or

backups into private residences. Such discharges are unauthorized by the federal Clean Water Act.

10 Issued and proposed operating permits are available online at dnr.mo.gov/env/wpp/permits/index.html. 11 When a permit expires, a facility remains bound by the conditions of that expired permit until either the permit is terminated or a

new permit is issued.

http://dnr.mo.gov/env/wpp/permits/index.html


15

Occurrences of sanitary sewer overflows can result in elevated bacteria concentrations (EPA 1996).

Despite the potential for bacteria loading from sanitary sewer overflows, a query for reported

overflows during the past five years in the Missouri Clean Water Information System, or MoCWIS,

did not return any results from these facilities. For this reason, sanitary sewer overflows are not

expected to be a significant contributor of pathogens to Mussel Fork.

5.1.2 Concentrated Animal Feeding Operations (CAFOs)

Concentrated Animal Feeding Operations, or CAFOs, are typically animal feeding operations that

confine and feed or maintain animals for 45 days or more in any 12-month period, and confine more

than 1,000 animal units. Facilities with fewer animal units may be permitted as CAFOs voluntarily, if

discharges occur or other water quality issues are discovered per 10 CSR 20-6.300. Animal wastes

generated from CAFOs that are carried through stormwater runoff or by wastewater discharges can

be a source of bacteria to water bodies (Rogers and Haines 2005). In general, CAFOs are permitted

as no discharge facilities with some allowances for certain catastrophic storm or chronic weather

conditions.12

In Missouri, CAFO facilities are permitted with either site-specific permits or under one

of two general permits; the MO-G01 CAFO permit or the MO-GS1 state no-discharge CAFO permit.

Under the MO-G01 permit, CAFO facilities are not permitted to discharge manure or process

wastewater, but exceptions are granted for discharges caused by excess stormwater runoff in

situations where the facility’s designed storage volume becomes exceeded by either a catastrophic

storm event or a chronic wet weather event as they are defined in the permit. Under the MO-GS1

permit, CAFO facilities are not allowed to discharge for any reason, without exception, and any

discharge is therefore a violation. One CAFO facility, Smithfield Hog Production, is permitted with a

site-specific permit. As with the generally permitted facilities, Smithfield is a no-discharge facility

and must land apply its wastewater. An exception for emergency discharge is allowed for specific

catastrophic storm conditions as defined in the permit under Special Condition #2 (see page 8 of

dnr.mo.gov/env/wpp/permits/issued/docs/0118478.pdf.) Per this special condition, only the portion

of stormwater flow that exceeds the defined catastrophic storm event may be discharged. CAFO

facilities operating in compliance with all specified permit conditions should not contribute

significant loads to surface waters. Table 6 describes the five CAFO facilities located within the

Mussel Fork watershed.

Table 6. CAFOs in the Mussel Fork watershed

Permit No. Facility Name Class13

Animal

Units

Manure Generated

(gallons/year)

MO-0118478 Smithfield Hog Production, Valley View Farm IA 49,459 80,287,225

MO-GS10083 L and D Farms IC 2,880 2,061,480

MO-GS10199 Lawrence Vasey IC 2,880 4,481,826

MO-GS10360 King Farms IC 1,920 1,982,717

MO-GS10490 Chris Dickell IC 1,984 1,589,575

Source: Missouri Clean Water Information System (MoCWIS)

Another potential source for bacteria loading from these operations is runoff from areas where animal

wastes are land applied as fertilizer. Land applications occurring on areas under the control of a

12

Storage structures should be properly designed, constructed, operated, and maintained to contain all manure, litter, process

wastewater plus the runoff and direct precipitation from the 25-year, 24-hour design storm event for the location of the CAFO. 13 An operation’s class size is a category that is based upon the total number of animal units confined at an operation. Class IA

facilities have 7,000 animal units or more. Class IC facilities have 1,000 or more animal units, but less than 3,000 animal units.

http://dnr.mo.gov/env/wpp/permits/issued/docs/0118478.pdf


16

CAFO are subject to conditions found in the permit and the nutrient management plans developed by

the facility. For these reasons, land application conducted by the CAFO facilities in compliance with

permitted conditions should not be contributing significant bacteria loads to Mussel Fork. However,

animal wastes from these CAFOs that are sold as fertilizers for areas not under the control of the

CAFO are not regulated by the department and may be potential nonpoint sources of bacteria. Such

land applications could occur either inside or outside of the watershed. Additionally, manure

fertilizers originating from locations outside the watershed may be transported for application to

areas within the watershed. For these reasons, bacteria contributions from manure applications cannot

be quantified, but could be significant due to the amount of land available for agricultural uses.

Unregulated agricultural nonpoint sources of bacteria, including animal feeding operations that do

not require a state operating permit, are discussed in greater detail in Section 5.2.1 of this document.

At this time there are no specific data available to determine the exact number or location of

unregulated animal feeding operations in the Mussel Fork watershed.

5.1.3 General Wastewater and Stormwater Permits

General and stormwater permits are issued based on the type of activity occurring and are meant to

be flexible enough to allow for ease and speed of issuance, while providing the required protection of

water quality. General and stormwater permits are issued to activities similar enough to be covered

by a single set of requirements, and are designated with permit numbers beginning with “MO-G” or

“MO-R” respectively. As of Feb. 23, 2016, there were no facilities in the Mussel Fork watershed

operating under a general wastewater permit and only one facility (Chris Dickell, Permit no. MO-

RA05456) with a general land disturbance stormwater permit. The department assumes that the

activities associated with this type of stormwater permit do not actively generate bacteria and that

activities conducted in compliance with all specified permit conditions, including all monitoring and

discharge limitations, will not contribute significant bacteria loads to surface waters. It is therefore

expected that compliance with this permit will be protective of the applicable designated recreational

uses within the watershed. If at any time the department determines that the water quality of streams

in the watershed is not being adequately protected, the department may require the owner or operator

of the permitted site to obtain a site-specific operating permit per 10 CSR 20-6.010(13)(C).

5.1.4 Illicit Straight Pipe Discharges

Illicit straight pipe discharges of domestic wastewater are also potential point sources of bacteria.

These types of sewage discharges bypass treatment systems, such as a septic tank or a sanitary sewer,

and instead discharge directly to a stream or an adjacent land area (Brown et al. 2004). Although

considered point sources, illicit straight pipe discharges are illegal and are not authorized under the

Clean Water Act. At present, there are no data about the presence or number of illicit straight pipe

discharges in the Mussel Fork watershed. For this reason, it is unknown whether straight pipe

discharges contribute bacteria loads to Mussel Fork. Due to the illegal nature of these discharges, any

identified illicit straight pipe discharges must be eliminated.

5.2 Nonpoint Sources

Nonpoint source pollution refers to pollution coming from diffuse, non-permitted sources that

typically cannot be identified as entering a water body at a single location. They include all other

categories of pollution not classified as being from a point source, and are exempt from department

permit regulations as per state rules at 10 CSR 20-6.010(1)(B)1. These sources involve stormwater

runoff and are minor or negligible under low-flow conditions. As indicated in Section 2.2, the


17

potential for runoff in the watershed is high. Typical nonpoint sources of pollution that have the

potential to influence water quality include various sources associated with runoff from agricultural

and non-MS4 permitted urban areas, onsite wastewater treatment systems, natural background

contributions and riparian corridor conditions.

5.2.1 Agricultural Runoff

Stormwater runoff from lands used for agricultural purposes is a potential source of bacteria loading

to water bodies. Activities associated with agricultural land uses that may contribute pathogens to a

water body include manure fertilization of croplands or pastures, and livestock production.

Stormwater runoff from croplands and grasslands that are fertilized with animal manure may be

potential sources of pathogens to waters due to improper applications or from soil erosion. As noted

in Section 2.4 of this document, cropland comprises approximately 5.6 percent of the Mussel Fork

watershed and areas categorized as being hay or pasture account for about 57 percent of the area.

Bacteria inputs resulting from soil erosion are more likely to occur from cropland areas, but bacteria

carried through stormwater runoff is a potential problem for both land use types if application rates

are too high, are made prior to inclement weather, or are made to frozen ground or other conditions in

which the manure cannot be readily incorporated into the soil (Fulhage 2000). In this region of the

state, manure fertilizers (other than those from CAFOs) are most likely generated from cattle.

Application rates and timing vary depending upon a number of factors, such as crop type, manure

quality and soil need. However, a typical application is less than 10 tons per acre and can be as high

as 20 tons per acre. When poultry litter is used, application rates are less and range from two to four

tons per acre. (Zachary Erwin, University of Missouri Extension, email communication, March 16,

2016).

In addition to manure spreading, livestock within the watershed may act directly as sources of

bacteria to streams due to either manure being deposited directly into a waterway or from manure

being carried by runoff from pasturelands or low density animal feeding operations that do not

require a CAFO permit. Although grazing areas are typically well vegetated, livestock tend to

concentrate near feeding and watering areas causing those areas to become barren of plant cover,

thereby increasing the possibility of erosion during a storm event (Sutton 1990). Stormwater runoff

can carry manure from these areas to nearby streams. Additionally, when livestock are not excluded

from a stream, direct manure contributions from cattle or other livestock to a water body become

more likely.

The permitted CAFO facilities in the Mussel Fork watershed are hog facilities and animal numbers

and manure rates are known as shown in Table 6. The number of other livestock that may be present

in the Mussel Fork watershed is unknown. Even so, an estimate of cattle numbers can be calculated

using the available land cover data in Section 2.4 and county cattle population numbers provided in

the U.S. Department of Agriculture’s 2012 Census of Agriculture. From these data, a number of

cattle per square mile of grassland for each county in the Mussel Fork watershed can be estimated.

And from these derived cattle densities, the number of cattle within the Mussel Fork watershed can

be estimated (Table 8). For beef cattle, the U.S. Department of Agriculture estimates that a 1,000

pound animal produces approximately 26.8 kilograms (59.1 pounds) of manure per day (USDA

1995).


18

Table 7. Cattle population estimates for pasture areas in the Mussel Fork, WBID 0674, watershed14

County

Cattle

(No. of animals)

Pasture

km2 (mi

2)

Cattle Density

No./km2 (No./mi

2)

Watershed Pasture

km2 (mi

2)

Watershed Cattle

(No. of animals)

Adair 37,295

674.02

(260.24)

55

(143)

34.14

(13.18) 1,878

Linn 46,905

850.12

(328.23)

55

(143)

17.38

(6.71) 956

Macon 42,691

916.73

(353.95)

47

(121)

39.63

(15.30) 1,863

Sullivan 40,638

979.27

(378.10)

41

(107)

106.01

(40.93) 4,346

TOTALS =

197.16

(76.12) 9,043

In addition to hogs and cattle, several other types of livestock operations may be present in the

Mussel Fork watershed. If present in the watershed, these other types of livestock could potentially

contribute bacteria loads to Mussel Fork. Table 8 summarizes the county-level data for these other

livestock that are noted in the 2012 Census of Agriculture. Some of these livestock may be confined

in lower-density animal feeding operations that may be acting as point sources, but are not regulated

under department regulations. There are no other data available to estimate the number or distribution

of these animals in the Mussel Fork watershed.

Table 8. Numbers of other livestock by county15

Livestock

Type

Adair County

(no. of animals)

Linn County

(no. of animals)

Macon County

(no. of animals)

Sullivan County

(no. of animals)

Sheep & Lambs 1,064 735 1,804 645

Goats 748 513 1,375 127

Equine 963 419 1,616 737

Poultry 9,456 891 2,003 754

5.2.2 Urban Stormwater Runoff

Urban stormwater runoff has been found to carry high levels of bacteria and can be expected to

exceed water quality criteria for bacteria during and immediately after storm events in most streams

throughout the country (EPA 1983). E. coli contaminated runoff can come from both heavily paved

areas and from open areas where soil erosion is common (Burton and Pitt 2002). Common sources of

E. coli contamination in urban stormwater have been documented as being from birds, dogs, cats, and

rodents (Burton and Pitt 2002). Therefore, in general, urban runoff is a potential contributor of

pathogens to surface waters. However, the Mussel Fork watershed is primarily a rural watershed with

very few urban spaces. Land cover data analyzed in Section 2.4 of this document identifies less than

5 percent of the watershed as being in a developed category. Of these areas categorized as being in

some level of development, the majority is contained within the boundaries of three small

municipalities. The largest of these municipalities is Green City with a population of 657, however

14 This analysis assumes all areas identified as being hay or pasture are being used for cattle grazing and that cattle are evenly

distributed on these areas. 15 Values that are “Not Given” were withheld by the U.S. Department of Agriculture to avoid disclosing data for an individual farm.


19

only 1.3 km2 (0.5 mi

2) of this municipality extend into the Mussel Fork watershed. Greencastle, a

municipality of 275 people accounts for 1 km2 (0.4 mi

2) of the watershed and Winigan, an

unincorporated community of only 44 people, covers 0.8 km2 (0.3 mi

2). Due to this small amount of

urban space in the watershed, urban stormwater runoff is not expected to be a significant contributor

of pathogens to Mussel Fork.

5.2.3 Onsite Wastewater Treatment Systems

Approximately 25 percent of homes in Missouri utilize onsite wastewater treatment systems,

particularly those in rural areas where public sewer systems may not be available (DHSS 2016).

Onsite wastewater treatment systems treat domestic wastewater and disperse it on the property where

it is generated, such as a home septic system. When properly designed and maintained, such systems

do not serve as a source of contamination to surface waters; however, onsite wastewater treatment

systems can fail for a variety of reasons. When these systems fail hydraulically (surface breakouts) or

hydrogeologically (inadequate soil filtration), there can be adverse effects to surface water quality

(Horsley & Witten 1996). Failing onsite wastewater treatment systems are known to be sources of

bacteria, which can reach nearby streams directly through surface runoff and groundwater flows,

thereby contributing bacteria loads under either wet or dry weather conditions. Onsite wastewater

treatment systems may contribute bacteria to waterbodies directly or as component of stormwater

runoff.

Unfortunately, the exact number of onsite wastewater treatment systems in the Mussel Fork

watershed is unknown. However EPA’s online input data server for the Spreadsheet Tool for

Estimating Pollutant Load, or STEPL, does provide estimates of septic system numbers by 12-digit

HUC watersheds based on 1992 and 1998 data from the National Environmental Services Center.16

Due to the relatively unchanged population estimates from 1990 to 2010 as described in Section 2.3

of this document, it is reasonable to assume that this older data can still provide a reasonable estimate

of septic system numbers in the Mussel Fork watershed. From this information, STEPL estimates that

there are approximately 117 septic systems in the Mussel Fork watershed. These STEPL derived

estimates are provided in Table 9 along with statewide estimated failure rates from the Electric

Power Research Institute (EPRI 2000). From this information, up to 59 onsite wastewater treatment

systems may be failing in the impaired watershed. For this reason, onsite wastewater treatment

systems are potential sources of bacteria loading; however the available data is inadequate to

determine the significance of such loading in relation to the impairment of Mussel Fork.

Table 9. Estimated numbers of septic systems in the Mussel Fork, WBID 0674, watershed

12-digit HUC

Subwatershed

name

Number of

Septic Systems

Statewide

Failure Rates

102802020301 Headwaters of Mussel Fork 80

30% – 50%

102802020302 Little Mussel Creek-Mussel Fork 24

102802020303 Painter Creek-Mussel Fork 13

Total = 117

16 The National Environmental Services Center is located at West Virginia University and maintains a clearinghouse for information

related to, among other things, onsite wastewater treatment systems. Available URL: www.nesc.wvu.edu/

http://www.nesc.wvu.edu/


20

5.2.4 Natural Background Contributions

Wildlife such as deer, waterfowl, raccoons, rodents, and other animals contribute to the natural

background concentrations of E. coli that may be found in a water body. Typical wildlife populations

are not expected to cause or contribute to water body impairments, but large congregations of

animals, such as migrating Canada geese, have been known to contribute significant bacteria loads in

some waters during times of the year when those animals are present in large numbers (Ishii et al.

2007). Watershed specific wildlife information is lacking, but general population estimates are

available in some cases from information provided by The Missouri Department of Conservation. For

example, statewide the Department of Conservation estimates that the resident Canada geese

population is approximately 69,500 birds (MDC 2014). For deer populations, harvesting data can be

used to provide a general idea of the amount of deer that may be present in an area. For the four

counties where the Mussel Fork watershed is located, approximately 12,564 deer were harvested

during the 2015 – 2016 deer season. Simulated statewide deer population values provided by the

Department of Conservation are approximately 75% greater than the number harvested (MDC 2016).

As is the case with livestock, bacteria contributions from wildlife can be a component of stormwater

runoff or directly deposited into a water body. Due to the lack of watershed specific data on the

potential bacteria contributions from wildlife, no estimation on the significance of such contributions

can be made. For purposes of this TMDL, wildlife contributions will be considered in the total

nonpoint source load as part of the established load allocation. No specific pollutant reductions from

wildlife sources are expected to be necessary to achieve the loading targets established in this TMDL

and implementation activities should focus on pollutant reductions from anthropogenic sources.

5.2.5 Riparian Corridor Conditions

Riparian, or streamside, corridor conditions can have a strong influence on instream water quality.

Wooded riparian buffers are a vital functional component of stream ecosystems and are instrumental

in the detention, removal and assimilation of pollutants from runoff. Therefore, a stream with good

riparian cover is often better able to moderate the impacts of high pollutant loads than a stream with

poor or no riparian cover. Table 10 presents land cover calculations for the riparian corridors within

the Mussel Fork watershed.

Table 10. Land cover in the riparian corridors of the Mussel Fork, WBID 0674, watershed

Land Cover Type

Area

hectares acres Percent

Developed, Low Intensity 4.05 10.01 0.13

Developed, Open Space 55.53 137.21 1.74

Cultivated Crops 241.19 596.00 7.56

Hay/Pasture 1,478.47 3,653.37 46.31

Forest 1,018.77 2,517.42 31.91

Shrub and Herbaceous 104.85 259.08 3.28

Wetlands 247.40 611.34 7.75

Open Water 42.21 104.30 1.32

Total: 3,192.47 7,888.73 100.00

This analysis of the riparian corridor used the same land cover data calculated in Section 2.4 of this

document and defined the riparian area as being a 30-meter (100-foot) buffer on each side of all


21

streams in the watershed that are included in the 1:24,000-scale National Hydrography Dataset.17

As

can be seen in Table 10, more than 46 percent of the land cover adjacent to streams in the watershed

is categorized as being hay and pasture. The close proximity of lands used for pasture or hay to

streams in the Mussel Fork watershed increase the risk of bacterial contamination due to potential

loading from runoff that has come in contact with manure or due to manure being directly deposited

into the stream from grazing livestock. For these reasons, the riparian corridor condition within the

Mussel Fork watershed may act as a potential source of bacteria loading due primarily to the

agricultural contributions that were discussed in greater detail in Section 5.2.1 of this document.

6. Numeric TMDL Target and Modeling Approach

As noted in Section 3.2 of this document, Missouri’s Water Quality Standards include specific

numeric E. coli criteria for the protection of recreational uses. The bacteria densities, or

concentrations, associated with the protection of whole body contact category B and secondary

contact recreation are geometric means of 206 counts/100 mL and 1,134 counts/100 mL respectively.

To calculate a TMDL for segment 0674 of Mussel Fork, the whole body contact recreation category

B criterion concentration of 206/100 mL will serve as the numeric target. Targeting this

concentration value will be protective of both whole body contact and secondary contact recreation in

Mussel Fork. The resulting TMDL will be expressed using a load duration curve that depicts daily

loads that vary with flow. E. coli loading at or below the load duration curve will result in achieving

water quality standards. However, it should be noted that although applied as a daily target for

purposes of a TMDL, because E. coli criteria are expressed as geometric means in the Missouri

Water Quality Standards, fluctuations in instantaneous instream bacteria concentrations are expected.

Therefore individual bacteria measurements in segment 0674 or in other downstream waters that are

greater than the applicable recreational use concentration do not in and of themselves indicate a

violation of water quality standards.

The load duration curve derived for a TMDL identifies the maximum allowable daily E. coli load for

any given day as a function of the flow occurring that day, which is consistent with the Anacostia

Ruling (Friends of the Earth, Inc., et al v. EPA, No 05-5010, April 25, 2006) and EPA guidance in

response to this ruling (EPA 2006; EPA 2007a). EPA guidance recommends that all TMDLs and

associated pollutant allocations be expressed in terms of daily time increments, and suggests that

there is flexibility in how these daily increments may be expressed. This guidance indicates that

where pollutant loads or water body flows are highly dynamic, it may be appropriate to use a load

duration curve approach, provided that such an approach “identifies the allowable daily pollutant

load for any given day as a function of the flow occurring on that day.” In addition, for targets that

are expressed as a concentration of a pollutant, it may be appropriate to use a table or graph to

express individual daily loads over a range of flows as a product of a water quality criterion, stream

flow and a conversion factor (EPA 2006).

The load duration curve approach is also useful in identifying and differentiating between storm-

driven and steady-input sources. The load duration approach may be used to provide a visual

representation of stream flow conditions under which bacteria criteria exceedances have occurred, to

assess critical conditions, and to quantify the level of reduction necessary to meet the surface water

quality targets for instream bacteria (Cleland 2002; Cleland 2003). To develop the load duration

curve for Mussel Fork, a flow duration curve was developed using average daily flow data collected

17

The National Hydrography Dataset is digital surface water data for geographic information systems, or GIS, for use in general

mapping and in the analysis of surface-water systems. Available URL: http://nhd.usgs.gov

http://nhd.usgs.gov/


22

from the stream. These data were corrected to the watershed area of the impaired segment based on

the ratio of that area to the drainage area of the stream gage. Additional discussion about the methods

used to develop the bacteria load duration curve is presented in Appendix B.

7. Calculating Loading Capacity

A TMDL calculates the loading capacity of a water body and allocates that load among the various

pollutant sources in the watershed. The loading capacity is the maximum pollutant load that a water

body can assimilate and still meet water quality standards. It is equal to the sum of the wasteload

allocation, load allocation and the margin of safety:

TMDL = LC = ∑WLA + ∑LA + MOS

Where LC is the loading capacity, ∑WLA is the sum of the wasteload allocations, ∑LA is the sum of

the load allocations, and MOS is the margin of safety.

According to 40 CFR 130.2(i), TMDLs can be expressed in terms of mass per unit time, toxicity or

other appropriate measures. For Mussel Fork, the pathogen TMDL is expressed as E. coli counts per

day using a load duration curve. Figures 8 presents the load duration curve for Mussel Fork. To

develop this load duration curve, the numeric TMDL target is multiplied by flow to generate the

maximum daily load at different flows.18

As shown in Figure 8, the resulting load duration curve represents the loading capacity and is

presented as a curve over the range of flows. The y-axis describes bacteria loading as counts per day

and the x-axis represents the frequency for which a particular flow is met or exceeded. Lower flows

are equaled or exceeded more frequently than higher flows. Estimates of instantaneous bacteria loads

calculated from the E. coli monitoring data in Appendix A are plotted as points. These observed

loads are presented only to illustrate flow conditions under which excessive bacteria loading may be

occurring. The flow condition ranges and descriptions presented in Figure 8 illustrate general base-

flow and surface-runoff conditions consistent with EPA guidance about using load duration curves

for TMDL development (EPA 2007b). Table 11 presents a summary of the TMDL loading capacities

and allocations for selected flow exceedances from the load duration curve.19

Specific allocations for

individual sources are presented and discussed in Sections 8 and 9 of this TMDL report.

18

𝐿𝑜𝑎𝑑 (count

time) = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 (

count

volume) ∗ 𝐹𝑙𝑜𝑤 (

volume

time)

19 Due to the extremely large numbers associated with bacteria loads, E. coli values are presented using scientific notation.


23

Figure 8. Mussel Fork, WBID 0674, load duration curve

Table 11. TMDL and allocation values for Mussel Fork, WBID 0674, at selected flows

Percent of time

flow exceeded

Flow

m3/s (ft

3/s)

TMDL

(counts/day)

∑WLA

(counts/day)

∑LA

(counts/day)

MOS

(counts/day)

95 0.01 (0.52) 2.62E+09 9.88E+08 1.37E+09 2.62E+08

75 0.11 (3.73) 1.88E+10 9.88E+08 1.59E+10 1.88E+09

50 0.52 (18.40) 9.28E+10 9.88E+08 8.25E+10 9.28E+09

25 1.78 (62.76) 3.16E+11 9.88E+08 2.84E+11 3.16E+10

5 18.61 (657.13) 3.31E+12 9.88E+08 2.98E+12 3.31E+11


24

8. Wasteload Allocation (Allowable Point Source Load)

The wasteload allocation is the allowable amount of the loading capacity that is assigned to existing

or future point sources. This section discusses the rationale and approach for assigning wasteload

allocations to point sources in the Mussel Fork watershed as well as considerations given for future

sources. A summary of all wasteload allocations is provided in Appendix C. Typically, point sources

are permitted with limits for a given pollutant that are the most stringent of either technology-based

effluent limits or water quality-based effluent limits. Technology-based effluent limits are based

upon the expected capability of a treatment method to reduce the pollutant to a certain concentration.

Water quality-based effluent limits represent the most stringent concentration of a pollutant that a

receiving stream can assimilate without violating applicable water quality standards at a specific

location. Effluent limits or other permit conditions must be consistent with the assumptions and

requirements of TMDL wasteload allocations per 40 CFR §122.44(d)(1)(vii)(B).

8.1 Municipal and Domestic Wastewater Discharges

Table 5 in Section 5.1.1 of this document notes that there are two facilities that discharge treated

municipal wastewater in the Mussel Fork watershed. Individual wasteload allocations calculated for

these facilities are based on the facility design flows and are presented in Table 12. However, actual

flows and available disinfection technologies may allow these facilities to discharge bacteria loads

less than those allocated. These allocations do not authorize these facilities to discharge bacteria at

concentrations that exceed water quality standards, but may serve to accommodate additional facility

loading due to any population increases or expansions in service area.

These allocations are applicable at all flows. At extremely low-flow conditions when the probably of

the flow being met or exceeded is 99 percent or greater, the load duration curve model predicts

effluent flows to dominate. Under these conditions the entire assimilative capacity of Mussel Fork

would be equal to the sum of the wasteload allocations. Disinfection or other permit conditions that

ensure protection of recreational uses will serve as an implicit margin of safety during periods in

which effluent flows dominate. Additionally, facility discharge monitoring report data shows that

these facilities are typically under loaded and often do not discharge during months associated with

lower flow conditions. Currently the permits for these facilities contain neither disinfection

requirements nor E. coli limits, but as previously mentioned in Section 5.1.1, revisions to state water

quality standards will now require these elements to be included upon permit renewal. Permit limits

targeting an E. coli concentration of 206 counts/100mL and that are protective of the whole body

contact recreation category B use are consistent with the wasteload allocations established in this

TMDL.

Table 12. Wasteload allocations for municipal wastewater dischargers

Permit No.

Facility

Name

Applicable

Outfall*

Design Flow

(as given in permit)

WLA

(counts/day)

MO-0103322 Greencastle Lagoon System 001 26,500 gallons/day 2.07E+08

MO-0112135 Green City Wastewater Treatment Facility 001 100,000 gallons/day 7.81E+08

* Outfalls not explicitly identified in this table are not expected to contribute to the impairment and current permit conditions

are expected to result in de minimis bacteria loading and should be maintained.

In addition to authorized discharges from municipal wastewater treatment facilities, areas serviced by

these types of systems risk bacteria contributions due to accidental sanitary sewer overflows. As


25

mentioned in Section 5.1.1 of this document, sanitary sewer overflows are unpermitted discharges

and are not authorized under the Clean Water Act. For this reason, sanitary sewer overflows in the

Mussel Fork watershed are assigned a wasteload allocation of zero at all flows. Occurrences of such

overflows are expected to continue to remain rare.

8.2 CAFOs

All CAFO facilities are permitted as no-discharge facilities and store wastewater in lagoons and land

apply accordingly. Assuming all permit conditions are met, including those associated with land

applications, CAFO facilities should not be contributing significant bacteria loads to Mussel Fork.

For this reason, the wasteload allocation for all CAFO facilities is zero at all flows.

8.3 General Wastewater and Stormwater Permits

Activities permitted through general or stormwater permits are not generally expected to contribute

significant bacteria loads to surface waters and the department assumes that such activities conducted

in compliance with all specified permit conditions, including land applications, monitoring and

discharge limitations, will not contribute significant bacteria loads to surface waters. It is expected

that compliance with these types of permits will be protective of the applicable designated

recreational uses within the watershed. For this reason these types of facilities are not assigned a

specified portion of the calculated wasteload allocation and loading from these sources is expected to

be at de minimis concentrations. Wasteload allocations for these facilities are set at existing permit

limits and conditions, which are assumed to be protective of all designated uses.

8.4 Illicit Straight Pipe Discharges

Illicit straight pipe discharges are illegal and are not permitted under the Clean Water Act. For this

reason, illicit straight pipe discharges are assigned a wasteload allocation of zero and any existing

sources of this type must be eliminated.

8.5. Considerations for Future Sources

For this TMDL, no specific portion of the loading capacity is allocated to a reserve capacity as

analysis of existing population data (see Section 2.3) and land cover data (see Section 2.4) indicate

little change from past conditions and a low likelihood of a need for such an allocation. However, the

wasteload allocations presented in this TMDL report do not preclude the establishment of future

point sources of bacterial loading in the watershed. Any future point sources should be evaluated

against the TMDL and the range of flows, which any additional bacterial loading will affect, as well

as any additional requirements associated with anti-degradation. Per federal regulations at 40 CFR

122.4(a), no permit may be issued when the conditions of the permit do not provide for compliance

with the applicable requirements of the Clean Water Act, or regulations promulgated under the Clean

Water Act. Additionally, 40 CFR 122.4(i) states no permit may be issued to a new source or new

discharger if the discharge from its construction or operation will cause or contribute to violation of

water quality standards.

Wasteload allocations calculated for existing municipal and domestic wastewater dischargers are

based on existing design flows. Use of design flows for calculating wasteload allocations instead of

the facilities’ actual flows account for future increases in discharge from these facilities. New

domestic wastewater treatment facilities and CAFO facilities that are permitted as no-discharge

facilities should not contribute additional bacteria loading to the impaired water bodies and do not


26

require a specified wasteload allocation for operation. However, land application from these new

facilities must be conducted in accordance with the requirements and conditions of the permit to

ensure no additional loading from such activities is occurring and that the sum of the TMDL’s

wasteload allocations is not being exceeded. Other general and stormwater permitted activities not

associated with domestic wastewater or CAFOs are not expected to actively generate bacteria and

compliance with all permit conditions is expected to result in loading at de minimis levels that will

not exceed the sum of the TMDL’s wasteload allocation. In some instances a potential source may be

re-categorized from a nonpoint source to a point source (e.g., newly designated or permitted

stormwater). If such a source’s magnitude, character, and location remain unchanged, then the

appropriate portion of the load allocation may be assigned as a wasteload allocation. Wasteload

allocations between point sources may also be shifted appropriately between individual point sources

where pollutant loading has shifted as long as the sum of the wasteload allocations is unchanged.

Advanced notification to EPA before permitting with shifts in the established wasteload allocation is

recommended (EPA 2012).

9. Load Allocation (Nonpoint Source Load)

The load allocation is the amount of the pollutant load that is assigned to nonpoint sources and

includes all existing and future nonpoint sources, as well as natural background contributions

(40 CFR § 130.2(g)). Load allocations for these TMDLs have been calculated as the remainder of the

loading capacity after allocations to the wasteload allocation and margin of safety. These total load

allocations are presented in Table 11.

Further disaggregation of the load allocation to develop separate allocations for urban runoff sources

and agricultural runoff sources could be calculated based on the proportion of land located within

municipal boundaries vs. rural agricultural areas. However, as described in Section 5.2.2., the

municipal areas within the watershed are mostly undeveloped and nearly indistinguishable from other

areas of the watershed. For this reason the load allocation will remain aggregated. No portion of this

load allocation will be assigned to onsite wastewater treatment systems as such systems should not be

contributing significant bacteria loads when properly designed and maintained. For this reason, these

systems are assigned a load allocation of zero at all flows.

10. Margin of Safety

A margin of safety is required in the TMDL calculation to account for uncertainties in scientific and

technical understanding of water quality in natural systems (CWA §303(d)(l)(C) and 40 C.F.R.

§130.7(c)(l)). The margin of safety is intended to account for such uncertainties in a conservative

manner. Based on EPA guidance, the margin of safety can be achieved through two approaches:

Explicit - Reserve a portion of the loading capacity as a separate term in the TMDL

Implicit - Incorporate the margin of safety as part of the critical conditions for the wasteload

allocation and the load allocation calculations by making conservative assumptions in the

analysis

For the Mussel Fork TMDL both an explicit and various implicit margins of safety are used in order

to ensure the water quality goals for Mussel Fork are met and that the designated uses of downstream

waters are protected. An explicit 10 percent of the loading capacity has been reserved to serve as a

margin of safety. Additionally, bacteria decay rates were not applied and the direct recreation-season


27

geometric mean was used for estimating the Clean Water Act required daily loading value.

Furthermore, wasteload allocations were calculated using the TMDL target concentration at the

design flow. Actual flows are typically much less and disinfection systems are designed and operated

to achieve close to 100 percent reduction of indicator bacteria. Therefore actual E. coli concentrations

from these sources will be much less than what is assumed by the TMDL. These various conservative

assumptions act as an additional implicit margin of safety.

11. Seasonal Variation

Federal regulations at 40 CFR §130.7(c)(1) require that TMDLs take into consideration seasonal

variation in applicable standards. Missouri’s water quality criteria for the protection of recreational

uses are applicable only during the recreational season. However, the TMDL load duration curve

represents streamflow under all conditions and use flow data collected during all seasons. For this

reason, the E. coli targets and allocations found in this TMDL report will be protective throughout

the recreational season and during flow conditions associated with storm-driven events, including

those associated with seasonal rain patterns, when bacteria loading is more likely. The advantage of a

load duration curve approach is that all flow conditions are considered and the constraints associated

with using a single-flow critical condition are avoided.

12. Monitoring Plans

Post-TMDL monitoring is often scheduled and carried out by the department approximately three

years after the approval of the TMDL or in a reasonable time period following completion of permit

compliance schedules and the application of new effluent limits. The department will routinely

examine physical habitat, water quality, invertebrate community, and fish community data collected

by other local, state and federal entities in order to assess the effectiveness of TMDL implementation.

In addition, certain quality-assured data collected by universities, municipalities, private companies

and volunteer groups may potentially be considered for monitoring water quality following TMDL

implementation. Determinations of water quality standards attainment or continued impairment of the

water bodies subject to this TMDL will be completed by the department as part of its biennial water

quality assessments for required Clean Water Act 305(b) and 303(d) reporting.

13. Reasonable Assurance

Section 303(d)(1)(C) of the federal Clean Water Act requires that TMDLs be established at a level

necessary to implement applicable water quality standards. As part of the TMDL process,

consideration must be given to the assurances that point and nonpoint source allocations will be

achieved and water quality standards attained. Where TMDLs are developed for waters impaired by

point sources only, reasonable assurance is derived from the NPDES permitting program. Issuance of

state operating permits and requiring that effluent and instream monitoring be reported to the

department should provide reasonable assurance that instream water quality standards will be met.

Where a TMDL is developed for waters impaired by both point and nonpoint sources, point source

wasteload allocations must be stringent enough so that in conjunction with the water body's other

loadings (i.e., nonpoint sources) water quality standards are met. This generally occurs when the

TMDL’s combined nonpoint source load allocations and point source wasteload allocations do not

exceed the water quality standards-based loading capacity and there is reasonable assurance that the

TMDL's allocations can be achieved. Reasonable assurance that nonpoint sources will meet their

allocated amount in the TMDL is dependent upon the availability and implementation of nonpoint


28

source pollutant reduction plans, controls or BMPs within the watershed. If BMPs or other nonpoint

source pollution controls make more stringent load allocations practicable, then wasteload allocations

can be made less stringent. Thus, the TMDL process provides for nonpoint source control tradeoffs

(40 CFR 130.2(i)). When a demonstration of nonpoint source reasonable assurance is developed and

approved for an impaired water body, additional pollutant allocations for point sources may be

allowed provided water quality standards are still attained. When a demonstration of nonpoint source

reasonable assurance does not exist, or it is determined that nonpoint source pollutant reduction

plans, controls or BMPs are not feasible, durable, or will not result in the required load reductions,

allocation of greater pollutant loading to point sources cannot occur.

A variety of grants and loans may be available to assist watershed stakeholders with developing and

implementing watershed based plans, controls and practices to meet the required wasteload and load

allocations in the TMDL and demonstrate reasonable assurance. Information regarding potential

participants, funding sources and implementation actions that address pollutant sources in the Mussel

Fork watershed can be found in the Chariton River E. coli TMDL Implementation Plan at

dnr.mo.gov/env/wpp/tmdl/0674-mussel-fk-ck-record.htm.

14. Public Participation

EPA regulations at 40 CFR§130.7 require that TMDLs be subject to public review. TMDLs

developed by the department are made available for public comment for a minimum of 45 days. A

45-day public notice period for this Mussel Fork TMDL was scheduled from Dec. 23, 2016 to Feb. 6,

2017. All comments received during this period and the department’s responses to those comments

will be made available online at dnr.mo.gov/env/wpp/tmdl/0674-mussel-fk-ck-record.htm.

Groups that directly received notice of the public comment period for this TMDL include, but are not

limited to:

Missouri Clean Water Commission

Missouri Water Protection Forum

Missouri Department of Conservation

Soil and Water Conservation Districts (Adair, Linn, Macon and Sullivan counties)

County health departments (Adair, Linn, Macon and Sullivan counties)

County commissions (Adair, Linn, Macon and Sullivan counties)

Green Hills Regional Planning Commission

Northeast Missouri Regional Planning Commission

Mark Twain Regional Council of Governments

University of Missouri Extension

Missouri Coalition for the Environment

Missouri Stream Team Watershed Coalition

Stream Team volunteers living in or near the watershed

Affected permitted entities

Missouri state legislators representing areas within the watershed.

In addition to those directly contacted, the public notice, TMDL, and an implementation plan have been

posted on the department’s TMDL webpage at dnr.mo.gov/env/wpp/tmdl/wpc-tmdl-progress.htm,

making them available to anyone with access to the Internet.



http://dnr.mo.gov/env/wpp/tmdl/wpc-tmdl-progress.htm


29

The department also maintains an email distribution list for notifying subscribers regarding significant

TMDL updates or activities, including public notices and comment periods. Those interested in

subscribing to TMDL updates may do so by submitting their email address using the online form

available at public.govdelivery.com/accounts/MODNR/subscriber/new?topic_id=MODNR_177.

15. Administrative Record and Supporting Documentation

An administrative record for the Mussel Fork TMDL has been assembled and is being kept on file

with the department. It includes any plans, studies, data and calculations on which the TMDL is

based, as well as any TMDL implementation plans, water body information sheets, the public notice

announcement, any public comments received and the department’s responses to those comments.

This information is available upon request to the department at dnr.mo.gov/sunshine-form.htm. Any

request for information about the Mussel Fork TMDL will be processed in accordance with

Missouri’s Sunshine Law (Chapter 610, RSMO) and the department’s administrative policies and

procedures governing Sunshine Law requests. For more information about open record/Sunshine

requests, please consult the department’s website at dnr.mo.gov/sunshinerequests.htm.

16. References

Brown, E., Caraco, D. and R. Pitt. 2004. Illicit Discharge Detection and Elimination a Guidance Manual

for Program Development and Technical Assessments. EPA X-82907801-0

Burton, A.G. Jr. and R.E. Pitt. 2002. Stormwater effects handbook, a toolbox for watershed managers,

scientists, and engineers. ISBN 0-87371-924-7 New York:CRC Press.

Chapman, S.S., Omernik, J.M., Griffith, G.E., Schroeder, W.A., Nigh, T.A., and T. F. Wilton. 2002.

Ecoregions of Iowa and Missouri (color poster with map, descriptive text, summary tables, and

photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,800,000).

Cleland, B.R., 2002. TMDL Development From the “Bottom Up” – Part II: Using Load Duration Curves

to Connect the Pieces. Proceedings from the WEF National TMDL Science and Policy 2002 Conference.

Cleland, B.R., 2003. TMDL Development from the “Bottom up” – Part III: Duration Curves and Wet-

Weather Assessments. America’s Clean Water Foundation, Washington, D.C.

DHSS (Missouri Department of Health and Senior Services). 2016. Onsite Wastewater Treatment

webpage. [Online WWW] Available URL: http://health.mo.gov/living/environment/onsite/ [Accessed 7

March 2016].

EPA (U.S. Environmental Protection Agency). 1983. Results of the Nationwide Urban Runoff Program –

Executive Summary PB84-185545.

EPA (U.S. Environmental Protection Agency). 1986. Design Manual – Municipal Wastewater

Disinfection. EPA/625/1-86/021

EPA (U.S. Environmental Protection Agency). 1996. Sanitary Sewer Overflows – What are they and how

can we reduce them? EPA 832-K-96-001

EPA (U.S. Environmental Protection Agency). 2006. Establishing TMDL “daily” loads in light of the

decision by the U.S. Court of Appeals for the D.C. Circuit in Friends of the Earth, Inc. v. EPA, et al., No.

https://public.govdelivery.com/accounts/MODNR/subscriber/new?topic_id=MODNR_177

http://dnr.mo.gov/sunshine-form.htm

http://dnr.mo.gov/sunshinerequests.htm

http://health.mo.gov/living/environment/onsite/


30

05-5015, (April 25, 2006), and implications for NPDES Permits. [Online WWW] Available URL:

https://www.epa.gov/tmdl/establishing-tmdl-daily-loads-light-decision-us-court-appeals-dc-circuit

[Accessed 15 March 2016].

EPA (U.S. Environmental Protection Agency). 2007a. Options for Expressing Daily Loads in TMDLs.

Office of Wetlands, Oceans & Watersheds. June 22, 2007.

EPA (U.S. Environmental Protection Agency). 2007b. An Approach for Using Load Duration Curves in

the Development of TMDLs. EPA 841-B-07-006.

EPA (U.S. Environmental Protection Agency). 2014. STEPL Data Server for Sample Input Data. [Online

WWW] Available URL: http://it.tetratech-ffx.com/steplweb/STEPLdataviewer.htm [Accessed 7 March

2016].

EPRI (Electric Power Research Institute). 2000. Advanced On-Site Wastewater Treatment and

Management Market Study: Volume 2

FGDC (Federal Geographic Data Committee). 2003. Federal Standards for Delineation of Hydrologic

Unit Boundaries. Working Draft. Version 1.1. [Online WWW] Available URL:

https://www.fgdc.gov/standards/projects/FGDC-standards-projects/hydro-unit-boundaries [Accessed 17

April 2015].

Homer, C.G., Dewitz, J.A., Yang, L., Jin, S., Danielson, P., Xian, G., Coulston, J., Herold, N.D.,

Wickham, J.D., and Megown, K., 2015, Completion of the 2011 National Land Cover Database for the

conterminous United States-Representing a decade of land cover change information. Photogrammetric

Engineering and Remote Sensing, v. 81, no. 5, p. 345-354 [Online WWW] Available URL:

http://www.asprs.org/a/publications/pers/2015journals/PERS_May_2015/HTML/index.html#345/z

[Accessed 17 Jul 2015].

Horsley & Witten, Inc. 1996. Identification and Evaluation of Nutrient and Bacterial Loadings to Maquoit

Bay, Brunswick, and Freeport, Maine.

Ishii, S., Hansen D., Hicks, R. and Sadowsky, M. 2007. Beach Sand and Sediments are Temporal Sinks

and Sources of Escherichia coli in Lake Superior. Environ Sci Technol 41, 2203 – 2209.

MDC (Missouri Department of Conservation). 2014. Waterfowl Hunting Digest 2014 – 2015. [Online

WWW] Available URL:

http://nature.mdc.mo.gov/sites/default/files/resources/2010/05/2014_waterfowl_digest.pdf [Accessed 01

June 2016].

MDC (Missouri Department of Conservation). 2016. Missouri Deer Season Summary & Population

Status Report. [Online WWW] Available URL:

https://huntfish.mdc.mo.gov/sites/default/files/downloads/Deer-Pop-status.pdf [Accessed 11 November

2016].

MoRAP (Missouri Resource Assessment Partnership). 2005. A gap analysis for riverine ecosystems of

Missouri. Final report, submitted to the USGS national gap analysis program. 1675pp.

https://www.epa.gov/tmdl/establishing-tmdl-daily-loads-light-decision-us-court-appeals-dc-circuit

http://it.tetratech-ffx.com/steplweb/STEPLdataviewer.htm

https://www.fgdc.gov/standards/projects/FGDC-standards-projects/hydro-unit-boundaries

http://www.asprs.org/a/publications/pers/2015journals/PERS_May_2015/HTML/index.html#345/z

http://nature.mdc.mo.gov/sites/default/files/resources/2010/05/2014_waterfowl_digest.pdf

https://huntfish.mdc.mo.gov/sites/default/files/downloads/Deer-Pop-status.pdf


31

NOAA (National Oceanic and Atmospheric Administration). 2014. NOAA Online Weather Data. [Online

WWW] Available URL: http://w2.weather.gov/climate/xmacis.php?wfo=eax

[Accessed 22 Feb. 2016].

NRCS (Natural Resources Conservation Service). 2007. National Engineering Handbook, Part 630

Hydrology, Chapter 7 Hydrologic Soil Groups.

NRCS (Natural Resources Conservation Service). 2011. Soil Survey Geographic Database (SSURGO).

[Computer file]. Available URL:https://gdg.sc.egov.usda.gov/

Rogers, Shane and John Haines. 2005. Detecting and Mitigating the Environmental Impact of Fecal

Pathogens Originating from Confined Animal Feeding Operations: Review. EPA/600/R-06/021.

U.S. Census Bureau (U.S. Department of Commerce). 2010. TIGER/Line Shapefile, 2010, 2010 state,

Missouri, 2010 Census Block State-based [ArcView Shapefile]. Available URL:

ftp://msdis.missouri.edu/pub/state/st_block10.zip

USDA (U.S. Department of Agriculture). 1995. Animal Manure Management – RCA Issue Brief #7.

[Online WWW] Available URL:

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcs143_014211 [Accessed 14 March 2016].

USGS (U.S. Geological Survey). 2009. Ecology-Ecological Drainage Units. [Online WWW] Available

URL: http://nh.water.usgs.gov/projects/ct_atlas/tnc_edu.htm [Accessed 22 Oct. 2010].

http://w2.weather.gov/climate/xmacis.php?wfo=eax

https://gdg.sc.egov.usda.gov/

ftp://msdis.missouri.edu/pub/state/st_block10.zip

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcs143_014211

http://nh.water.usgs.gov/projects/ct_atlas/tnc_edu.htm


32

Appendix A

Mussel Fork recreational season E. coli data (2010 – 2014)20,21

Site Code Site Name Date

Sample ID

E. coli (counts/100ml)

Flow m

3/s (ft

3/s)

674/28.8 Mussel Fork near Mystic 4/22/2010 200742 130 0.048 (1.70)


674/28.8 Mussel Fork near Mystic 6/16/2010 200744 7,100 1.812 (64.00)


























20

Recreational season E. coli data was retrieved from the department’s Water Quality Assessment Database on Feb. 19, 2016. 21 All data was collected by the U.S. Geological Survey.


33

Appendix B

Development of the Mussel Fork Bacteria Load Duration Curve

Overview

The load duration curve approach was used to develop the total maximum daily load, or TMDL, for

the impaired water body segment of Mussel Fork, WBID 0674. The load duration curve method

allows for characterizing water quality concentrations (or water quality data) at different flow

regimes and estimating the load allocations and wasteload allocations for each impaired segment.

This method also provides a visual display of the relationship between stream flow and loading

capacity. Using the duration curve framework, allowable loadings are easily presented.

Methodology

Using the load duration curve method requires a long time series of flow data, a numeric water

quality target, and bacteria data from the impaired streams. For the Mussel Fork TMDL, bacteria data

collected from the impaired segments was converted into an instantaneous load using measured

flows. These observed loads were plotted along with the load duration curve to illustrate conditions

when the water quality target may have been exceeded.

To develop a load duration curve, a long record of average daily flow data from a gage (or multiple

gages) that is representative of the impaired reach is used. The flow record should be of sufficient

length to be able to calculate percentiles of flow. If a flow record for an impaired stream is not

available, then a synthetic flow record is needed. For the Mussel Fork TMDL, flow gage data from

Dec. 11, 2002 to Jan. 27, 2016, was available from Mussel Fork via USGS gage 06906000. The

modeling approach assumes that discharge at the outlet of the impaired watershed is proportional to

the discharge from the USGS gage station. Therefore, average daily flow values were corrected based

on the proportion of the area draining to the impaired watershed to that draining to the flow gage

(Table B-1). The developed flow duration curve for the impaired water body is presented in Figure

B-1. These flows in units of ft3/second are then multiplied by the selected water quality target of 206

counts/100 mL and a conversion factor of 24,465,715 in order to generate the allowable load in units

of counts/day.22

Despite the varying load, the targeted concentration is constant at all flow percentiles

and reflects the static nature of the water quality standards.

Table B-1. Information used to calculate area corrected flows

Location: USGS 06906000 WBID 0674

Drainage Area: 691.5 km2 (267 mi

2) 326.3 km

2 (126 mi

2)

Correction Factor: n/a 0.47191

22

𝐿𝑜𝑎𝑑 (count

day) = [𝑇𝑎𝑟𝑔𝑒𝑡 (

count

100ml)] ∗ [𝐹𝑙𝑜𝑤 (

𝑓𝑒𝑒𝑡3

𝑠)] ∗ [𝐶𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟]


34

Figure B-1. Flow duration curve (Mussel Fork, WBID 0674)


35

Appendix C

Summary of Wasteload Allocations*

(See Section 8 for more specific wasteload allocation information)

Permit No. Facility Name

Applicable

Outfall

Design Flow

(gal/day)

WLA

(count/day)

MO-0103322 Greencastle lagoon system 001 26,500 2.07E+08

MO-0112135 Green City WWTF 001 100,000 7.81E+08

MO-0118478 Smithfield Hog Production, Valley View Farm All No discharge 0

MO-GS10083 L and D Farms All No discharge 0

MO-GS10199 Lawrence Vasey All No discharge 0

MO-GS10360 King Farms All No discharge 0

MO-GS10490 Chris Dickell All No discharge 0

General/Stormwater

Permits n/a

All n/a

Existing

limits and

conditions

Illicit Straight Pipes n/a All n/a 0

Sanitary Sewer

Overflows Greencastle and Green City sewerage systems

All n/a 0

* Outfalls not explicitly identified in this table are not expected to contribute to the impairment and current permit conditions are

expected to result in de minimis bacteria loading and should be maintained.

total maximum daily load (tmdl) - dnr · completed: feb. 8, 2017 approved: mussel fork e. coli tmdl...

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