concentration and sources of fecal and organic …lshs.tamu.edu/docs/lshs/end-notes/concentration...

WATER RESOURCES BULLETIN VOL. 15, NO. 4 AMERICAN WATER RESOURCES ASSOCIATION AUGUST 1979

CONCENTRATION AND SOURCES OF FECAL AND ORGANIC POLLUTION IN AN

AGRICULTURAL WATERSHED'

Daniel R . Dudley and James R . Karr'

ABSTRACT: Fecal contamination and organic pollution of an agricultural drainage in north- east Indiana was high. Bacterial counts (total coliform, TC; fecal coliform, FC; and fecal streptococcus, FS) and biochemical oxygen demand (BOD) were used to assess waste concentrations. Coliform counts indicated that sections of the drainage receiving septic effluent had waste concentrations far in excess of public health standards (mean FC = 550,000/100 ml). Areas of drainage remote from septic tank pollution were found to occasionally meet federal public health standards for whole body contact recreation but generally these areas had twice the allowable limit of 200 FC/lOO ml. Bacterial contamination was highest during runoff events when the median values for TC, FC, and FS were 5,3, and 17 times greater, respectively, than the median values during low stream discharge. Surface flows carried contaminants from unconfined livestock operations and fecally contiminated sediment was transported by high waters. During one runoff event a BOD loading of 36.7 kg/km2 was recorded and the peak BOD concentration observed was 16 mg/l. A discharge of liquid manure from a confined livestock operation caused a major fish kill. Pollution from septic tanks and unconfined livestock is greatest at high stream discharge when dilution reduces the impact on aquatic life. (KEY TERMS: bacterial pollution; BOD; agricultural runoff; coliform bacteria; fish kill; water pollution sources.)

INTRODUCTION Organic pollution, especially in the form of fecal contamination, is a concern for

several reasons. Potential human health hazards from water borne pathogens can exist in any fecally contaminated water but the risks have been found to increase substantially when fecal coliforms are above 200 counts per 100 ml (Geldreich, 1970). Low to moderate levels of organic pollution influence the type of aquatic community present in a stream and gross organic pollution represents a threat to the survival of downstream fish populations (Hynes, 1960). Although the problem of organic pollution in agricultural areas has been recognized for some time, the traditional concerns of water pollution control have centered on large municipal and other point sources of organic pollution. Regu- lations calling for water quality planning in non-point areas necessitates an evaluation of the degree of organic and fecal pollution in rural areas.

'Paper No. 78044 of the Water Resources Bulletin. Discussions are open until April 1, 1980. 'Respectively, Aquatic Biologist, Allen County Soil and Water Conservation District, 2010 Inwood,

Fort Wayne, Indiana 46805 ; and Associate Professor, Department of Ecology, Ethology, and Evolu- tion, University of Illinois, Champaign, Illinois 61 820.

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Organic pollution and fecal contamination has been documented in runoff from barnlots (White, 1972), dairy farms (Janzen, et al., 1974), cropland (Weidner, et al., 1969; Smith and Douglas, 1973; Burwell, et ul., 1974; Harms, e t al., 1975), andseptic tank drainfield systems (Reneau, et al., 1975). Large numbers of fecal coliforms reached an estuary of Chesapeake Bay from a rural watershed (Faust, 1976). Both urban and agricultural watersheds in New Jersey contained high levels of organic pollution (Yu, et al., 1975).

In this paper we present the results of a two year study of bacterial contamination and biochemical oxygen demand (BOD) in a 48.5 km2 (12,000 acre) agricultural watershed. Probable sources of contamination are discussed and contamination levels are compared with federal guidelines.

METHODS AND MATERIALS

Study Area The Black Creek drainage in Allen County, Indiana (15 miles NE of Fort Wayne,

Indiana) has been the subject of an intensive demonstration and research project designed to reduce soil erosion in an agricultural watershed. The project was designed to investi- gate the relationship between soil conservation practices and water quality. Results of agricultural, economic, and other biological studies in the watershed can be found in the Black Creek final report (Morrison,et al., 1977).

The Black Creek watershed is a 48.5 km2 (12,000 acre) drainage within the Maumee River basin and is representative of the soils and land use of the larger Maumee basin. Soils range from the silty clay loam of the Fort Wayne moraine to the medium and fine textured, high clay soils associated with glacial Lake Maumee. Eighty percent of the Black Creek watershed is cropland while 4 percent is urban. Woodland and pasture make up the remaining area. There are three areas of differing topographic relief within the watershed: the rolling upland of the Fort Wayne moraine (2-6% slopes), the glacial lake bed area (0-2% slopes), and a transitional area between these two known as the beach ridge (Figure 1). Farms on the lake plain area are generally more progressive than farms on poorer quality upland areas. An Amish community farms 60 percent of the upland area without the use of modem equipment. Typically, an Amish farm has 15-20 head of dairy cattle, 10-15 work horses, and 20-30 head of hogs. Therefore, large numbers of livestock in pasture or barnlots contribute to the organic pollution of the upper Dreisbach and Wertz Drains (Figure 1). In contrast, more contemporary lake plain farms have confined livestock feeding operations that are equipped with waste holding facilities. Under proper management, these are not a major source of organic pollution in Black Creek.

Domestic waste from a rural community and recent “strip” housing developments along major roads are another source of organic pollution in the Black Creek watershed. Homeowners both in the community of Harlan (population 600) and throughout the watershed rely on septic tank systems for treatment of sewage. The slow percolation rates of heavy clay soils limit the effectiveness of these systems. Therefore, a high per- centage of the septic tanks have off-lot discharges into nearby streams or tile systems.

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Organic Pollution in an Agricultural Watershed

Figure 1. Map of the Black Creek Watershed Showing Location of Sampling Stations and Late Summer Flow Conditions.

Bacteriological Sampling Water samples for microbiological analysis were collected from 42 stations (22 sur-

face, 20 tile) during the period March 1976 through May 1977 (Figure 1). Samples were taken at three month intervals at stations where water was present. Many stations could not be sampled on one or more of the six sampling dates because of dry conditions. Nineteen surface water stations were located in the Black Creek watershed at the lower end of tributary drains which enter Black Creek and at approximately one mile intervals along Black Creek, the Richelderfer Drain, and the Dreisbach Drain. An additional station was located on the Wertz Drain. Three stations outside the watershed included two on Wann Ditch east of the Black Creek Study Area at Killian Road and one on the Maumee River at Route 101.

Tile systems were selected to represent the major soil types in the watershed. Because of a severe drought in 1976-77, 55 of 120 potential samples were not obtained because tiles were not flowing. Six tile lines connected to septic tank systems flowed regularly. All tile systems sampled in this study were also sampled in another phase of the project for suspended solids and nitrogen and phosphorus fractions (Morrison, et al., 1977).

Samples were collected in sterilized 100 ml glass bottles by immersing them at the water’s surface. Generally a single sample was collected at each station although occasionally triplicate samples were collected to establish sampling variability. Testing procedures were initiated five hours or less after sample collection. The Allen County Board of Health laboratory conducted the testing. The membrane filter technique was used

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following Standard Methods (American Public Health Association, 1971) and the recom- mendations of the Millipore Company. After serial dilution of the samples, plates were inoculated. The media used were m-Endo MF broth (Millipore), m-FC broth (Millipore) and KF streptococcus agar (Difco) for total coliform, fecal coliform and fecal streptococcus tests, respectively. The incubation and counting procedures outlined in Standard Methods were followed. Throughout this report the bacterial concentrations are expressed on the basis of counts per 100 ml of water.

BOD Sampling Samples for biochemical oxygen demand (BOD) analysis were collected during a major

storm event on June 30, 1977 (7.1 an rainfall). Sample sites were selected to represent a variety of conditions: for example, urban vs. agricultural, Amish vs. conventional farms. Composite samples were also made from water collected by automated pump samplers at two locations (Figure 1). These automated stations were equipped with calibrated weirs and stream stage recorders and provided data on stream discharge. At stream stages above one foot, the automated pump samplers collected water samples every 30 minutes during the course of the storm event. Composite samples for BOD analysis were made at the end of the event by combining 50 ml of water from each sample taken by the pump sampler. BOD loading was calculated by multiplying the BOD concentration of the composite sample by the volume of runoff measured during the time interval the pump samplers were operating.

In addition, six grab samples were collected for BOD analysis and ammonia-N analysis during a major fish kill, September 29, 1977. Samples were taken from the tile line dis- charging the pollutant and at upstream and downstream locations.

Samples for BOD studies were collected in 2 liter polyethylene containers and refri- gerated until laboratory set-up was initiated the next day. Laboratory analysis for BOD and ammoniaN was done by Pollution Control Systems, Inc. (Laotto, Indiana) following the procedures of Standard Methods (American Public Health Association, 1971).

RESULTS

Sample Variability The high level of variability in bacterial counts (C.V. 30 to 75) and incomplete data

records during a dry period suggests caution in examination of data from individual stations. Consequently, we shall avoid detailed station-by-station analysis and concentrate on groups of similar stations. Further, since flow volumes varied among the sample dates two flow classes were defined: low flow when no surface runoff could be detected and high flow when there was substantial surface runoff (Table 1). Among the six sample dates five were low and one was high.

Bacterial Counts in Surface Waters Sixty-five samples were collected at low flow and 20 samples were taken at high flow

conditions (Table 2). Mean values are high because of very high counts near septic tank outfalls. Therefore, we use median values as more representative of bacterial contamination. Without exception bacterial counts were higher under high flow than under low flow conditions (Table 2).

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TABLE 1. Sampling Dates and Stream Discharges at Two Sites in the Black Creek Watershed (discharge class is based on the

occurrence of surface runoff from agricultural land).

Date

Average Daily Discharge (m3/sec.)

Discharge am Site 2 Site 6

29 March 1976 Low 0.048 0.025

7 June 1976 LOW 0.008 0.004

23 August 1976 Low 0.004 0.000

29 November 1976 Low 0.000 0.002

28 March 1977 High 1.077 0.775

3 1 March 1977 Low 0.001 0.001

TABLE 2. Bacterial Counts (count/100 ml water) Observed in the Black Creek Watershed at Low and High Stream Discharge.

Total Fecal Fecal Coliform Cdiorm Streptococcus

Low Stream Discharge*

Range

Median Mean

High Stream Discharge**

Range

Median Mean

100- 2,600,000

3,500 165,000

600- 92,800

18,000 26,000

0-

2,600,000

1,000 109,000

0 -- 36,000

3,400 4,900

0- 890,000

200 19,000

0- 10,000

3,400 4,200

*Data from 65 observations taken at 20 surface water stations on 5 sampling dates in 1976 and 1977. **Data from 20 observations taken at 20 surface water stations on 28 March 1977.

When not carrying storm runoff, some streams in the Black Creek watershed maintained a base discharge from ground water, others ceased to have any discharge and in the summer months became a series of isolated pools, and a few sections of stream had an

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intermittent flow arising from domestic waste effluent (Figure 1). To facilitate compari- sons among stations, six groups of stations were identified on the basis of proximity of sewage outfalls and discharge regime during low flow periods (Figure 2). There are no significant differences among the group means even when stations are so grouped. How- ever, the frequency distribution of six levels of bacterial contamination illustrates differences among the groups (Figure 2). Groups D and A, stations with high levels of organic pollution, had broad distributions of total colifonn counts and high median values. The moderately polluted groups, B and E, also had wide distributions but much lower median total coliform counts. The remaining two groups, F and C, had low levels of pollution, a narrower distribution of total coliform counts and still lower median values. The distribution of fecal coliform counts was very similar to that for total coliforms. Fecal streptococcus contamination was slight except in the highly polluted areas where median counts were 5,050 (Group D) and 1,600 (Group A). The remaining groups of stations had median counts less than 200 fecal streptococci per 100 ml water.

At low stream discharge the degree of fecal contamination was primarily dependent upon the proximity of sewage outfalls and not the flow regime in the stream. The fecal coliform counts indicate that sections of the Black Creek drainage that received septic waste had fecal contamination far in excess of any public health standards. Areas of the drainage remote from septic tank pollution occasionally met federal public health standards for whole body contact recreation (Fed. Wat. PCA 1968) but generally these areas had twice the allowable limit of 200 fecal coliforms per 100 ml of water. At low stream discharge total coliform concentrations were above the maximum acceptable levels (10,000/100 ml) only at septic tank outfalls.

On March 28, 1977, there was considerable surface runoff from agricultural land and stream discharge in Black Creek was high (0.775 m3/sec.). Mean and median bacterial counts were not greatly different because septic tank effluent in the badly polluted stream sections was being diluted (Table 2). The median values for total coliform, fecal coliform, and fecal streptococcus counts were 5 , 3, and 17 times greater, respectively, than the median values during low stream discharge (Table 2).

Increases in total and fecal coliform counts were caused by higher counts at stations on Black Creek downstream of Harlan. Tributary drains not influenced by Harlan showed only a slight increase in coliform contamination over low stream discharge levels (Table3); these data suggest that storm runoff from agricultural land is not the major source of coliforms. Rather, the source of high coliform counts in high flow periods is material depo- sited as bottom sediment at septic tank outfalls. This sediment is transported downstream during storm events.

Fecal streptococcus contamination increased at all stations on the watershed during high flow. The increase was particularly strong above Harlan on the Dreisbach Drain. A grassed waterway and an open ditch in this section of the watershed carried fecal streptococcus counts from 5,000 to 10,000 per 100 ml water. Slightly lower levels of contamination (3,000 - 9,000) were maintained along the lower Dreisbach Drain, the Richelderfer Drain and Black Creek. Other tributary drains had from 0 to 3,500 fecal streptococcus per 100 ml water. Thus the agricultural area of upper Dreisbach Drain and the town of Harlan were the major identifiable areas of fecal streptococcus contamination at high stream discharge. In these areas contamination was more than an order of magnitude greater than the levels of pollution observed at low stream discharge. We conclude that runoff from barnlots and/or pastures of the noncontemporary (Amish)

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livestock operations was responsible for substantial fecal pollution of storm runoff in the Black Creek watershed.

Total Coliform Fecal Coliform Fecal Streptococcus

0,9 10 0.4

C 5

ul C 0

a .- +

F 5

Bacter ia l Count Classes

Figure 2. The Frequency of Six Ranges of Bacterial Counts Found in Different Areas of the Black Creek Watershed (station groupings A-F) a t Low Stream Discharge.

[The range of the bacterial count classes are: 1, 0-100; 2, 100-1,000; 3, 1,000-10,000; 4, 10,000-50,000; 5 , 50,000-500.000; 6 , > 500,000. Grouping A - Isolated pool, high pollution; B - Isolated pool, moderate pollution; C - Isolated pool, low pollution; D - Intermittent flow, high pollution; E - Intermittent flow, moderate pollution; F - Base flow, low pollution. Numbers (x -lo3) indicate mean (upper) and median (lower) bacterial counts.]

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TABLE 3. Median Values for Total Coliform and Fecal Coliform Counts at Stations Downstream from the Town of Harlan and at Stations not Influenced

by Harlan or Any Other Large Source of Septic Pollution.

Total Cdiform Fecal Coliform

LOW fish L O W High Discharge Dipcharge Discharge Discharge

Stations Downstream of Harlan 2,850 32,000 600 5,300

Stations Not Influenced by Harlan 1,800 2,500 500 700

For comparative purposes surface water samples were collected from the Maumee River and Wann Ditch. The Maumee River is the receiving body for Black Creek. Wann Ditch is a small stream adjacent to the Black Creek watershed which lacks any concentrated urban area. Wann Creek is comparable to Sampling Group C of Black Creek. Bacterial counts were similar to those reported from stations in Group C including increased fecal streptococcus counts at high stream discharge.

Counts from the Maumee River were wide ranging, probably being a function of discharge, as the highest counts were recorded in the spring. Fecal coliforms were generally fairly low (200-500 counts per 100 ml.) but at high discharge the counts increased an order of magnitude (4,000-15,000). Fecal streptococci were detected only once at the Maumee River station during a period of high stream discharge (March 20,1977). Com- pared to the waters of the Black Creek drainage the Maumee River had approximately the same concentration of total coliforms but lower concentrations of fecal coliforms and fecal streptococcus (excluding periods of high stream flow).

Bacterial Counts in Subsurface Water Tile drainage samples derive from high or low flow conditions and from septically or

not-septically polluted tile systems (Table 4). Predictably, septically polluted tiles had high average values during low flow when there was very little dilution of septic waste by natural drainage water. At high flows these same tiles carried far lower concentrations of bacteria because of dilution by subsurface drainage water. Nonseptically polluted tile systems had low levels of coliform contamination that remained unaffected by discharge rates. Total coliform counts were very similar at high and low discharge; a small increase in fecal coliform concentrations at high flow resulted from high values at two tiles with surface water inlets.

Fecal streptococcus contamination of nonseptically polluted tile systems increased at high flow for most stations. At low flow, only 1 of 14 stations had counts over 100. At high flow 10 of 14 stations had fecal streptococcus counts between 100 and 500 while two tiles with surface water inlets had counts an order of magnitude greater. Nonsepti- cally polluted tile systems were an identifiable source of fecal streptococcus contamination at high stream discharge. However, the degree of contamination was low and fecal

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coliforms were generally not detected suggesting fecal material was not the contaminat- ing source. Instead, this bacterial contamination was probably caused by Streptococcus faecalis var. liquifaciens, a common organism on vegetation and in soil that is frequently isolated from good quality water (Geldreich and Kenner, 1969).

TABLE 4. The Mean Total Coliform (TC), Fecal Coliform (FC) and Fecal Streptococcus (FS) Counts for Six Septically Polluted and Fourteen Not-

Septically Polluted Tile Drainage Outlets (N = number of samples).

Septically Polluted Not-Septically Polluted

Mean N Mean N

Low Flow TC 330,000 21 2,300 24 FC 6 1,000 21 60 25 FS 30,000 21 10 25

High Flow TC 9,700 5 2,300 14 FC 2,300 5 400 14 FS 5,900 5 2,200 14

Sources of Contamination An indication of the sources of fecal pollution is given by the fecal coliform/fecal

streptococcus ratio (FC/FS). A ratio greater than 4 indicates human sources of pollution, a ratio less than 0.7 indicates an animal source, and ratios between 0.7 and 4 indicate combined human and animal fecal pollution (Geldreich and Kenner, 1969). At low flows in the Black Creek watershed, the dominant source of fecal contamination was human but there was a significant (x2 = 22.6, p < 0.01) shift from human to mixed human and animal sources of pollution when discharge increased. This shows that livestock operations had a substantial impact on the fecal contamination of storm water runoff. Surface water stations in the upper Dreisbach agricultural area exhibited the greatest degree of fecal contamination from livestock while surface water stations in other areas showed either livestock sources or mixed human and animal sources.

BOD Concentrations Paired samples from watersheds of about 50 acres in the rolling upland yielded high

BOD concentrations from Amish land relative to land with conventional farming methods (Table 5). Apparently, unconfined livestock in the Amish area substantially increased the amount of organic matter in surface runoff.

One sample, taken from a large tile outlet with surface inlets near a contemporary confined livestock-feeding operation, had exceptionally high BOD (480 mgll). This is roughly equivalent to raw sewage (Hynes, 1960), even though the feedlot is equipped with properly designed waste holding facilities. Apparently, the control of manure wastes is less than 100% effective. The tile outlet was sampled during the initial phase of the storm

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Dudley and Karr

and surface runoff was just beginning so the volume of discharge was small. It is doubt- ful that BOD concentrations remained this high during peak storm runoff because dilution is increased. In terms of total BOD loading, this type of runoff from a confined feeding operation cannot be considered a major source within the watershed. However, such sources may raise BOD concentrations in streams above the concentrations found in runoff from cropland. Also, highly concentrated organic matter delivered to streams in this manner could be locally damaging if rainfall and runoff are not sufficient to dilute and flush away the organic matter at the outfall.

TABLE 5. Biochemical Oxygen Demand (BOD) Found at Six Grab Sample Locations During a Storm Event, June 30,1977, and the BOD of

Composite Samples Taken Throughout this Storm Event (the predominant feature suspected of influencing BOD is also listed).

Predominant Feature of Watershed BOD mg/l

Grab Samples: Amish Farming Amish Farming (Wertz Drain) Conventional Farming Urban (Dreisbach Drain) Urban (Richelderfer Drain) Confined Feeding Operation (Tile Drain)

Composite Samples: Site 2 - Conventional Farming - No Urban Buildup Site 6 - Amish Farming - Urban Buildup

12.0 16.0 6.6

14.0 16.0

480.0

6.3 9.3

Grab samples were taken on the three major drains of Black Creek prior to peak flows on June 30 (Table 5). BOD concentrations were similar in all three samples ranging from 14 to 16 mg/l. Two of the samples were taken downstream from the town of Harlan and the other from a predominantly Amish farming area. The urban area with its septic effluent and the Amish area with a large number of unconfmed livestock appear to be the factors that created higher BOD concentrations in stream flows (14-1 6 mg/l) compared to runoff from conventional cropland (6.6 mg/l).

Composite samples collected from the Smith-Fry Drain (Site 2) and the Dreisbach Drain (Site 6) also illustrate the effect of urban buildup and Amish farming practices on BOD concentrations. The Smith-Fry watershed lacks any urban influence and the area is farmed predominantly by conventional methods. The Dreisbach watershed contains the town of Harlan and a large number of Amish farms. Composite BOD concentrations for Sites 2 and 6 were 6.3 and 9.3 mg/l, respectively. BOD loadings for this storm were 364 and 239 kg at Sites 2 and 6, respectively. More rainfall and runoff on the Smith-Fry watershed accounted for the greater loading at Site 2. Expressed on an areal basis, BOD losses for this single storm were 40.9 kg/km2 for the Smith-Fry watershed and 32.5 kg/ km2 on the Dreisbach watershed.

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Fish Kill Caused by Organic Pollution On September 29, 1977, several thousand gallons of manure slurry were accidentally

discharged into Black Creek when an animal waste holding lagoon was emptied directly onto adjoining cropland. The slurry entered a subsurface tile network through broken tile lines and/or surface inlets and was delivered to the stream with very little dilution (Table 6). The impact at the outfall was devastating and low stream flows were inade- quate to dilute the pollutant to nontoxic levels. m e material moved downstream as a slug which could be visually detected. Three downstream samples had very high BOD (130-300 mg/l) even prior to the arrival of the main slug of pollutant. Ammonia N concentrations were also greatly elevated (Table 6).

Fish mortality was severe in the entire 9 kilometers of stream below the spill. Mor- tality probably resulted from low oxygen levels and/or an ammonia toxicity. Detailed notes on this fish kill have been reported elsewhere (Morrison, et al., 1977) but its occurrence is mentioned here to illustrate the pollution hazards of confined livestock feeding operations. Accidental or intentional discharge of organic pollutants from animal waste holding facilities can create gross organic pollution in streams when discharge is low and potential damage is the greatest. Widespread organic pollution from other sources (septic tanks and unconfined livestock) is greatest at high stream discharge when dilution reduces the impact on aquatic life.

TABLE 6 . BOD and Ammonia N Concentrations of Grab Samples Taken on Black Creek During a Major Fish Kill (September 28,1977) (one sample was taken just upstream from

the source of pollutant and four samples were taken at various distances downstream).

Sample Location

BOD mgD

Ammonia N mg/l

Upstream Source (tile line) Downstream 100 m Downstream 580 m Downstream 1720 m Downstream 2440 m

2.1 28,000

7,200 130 2 20 3 00

1.2 2,400

600 1 1 18 20

DISCUSSION Water quality plans for rural areas must consider fecal contamination as a human health

hazard and organic pollution in terms of its impact on the aquatic life of the stream. The concerns for human health standards are obviously of primary importance. Current federal guidelines dictate 200 FC/100 ml for whole body contact recreation, 1000 FC/ 100 ml for other water recreation activities, and 2000 FC/lOO ml and 10,000 TC/lOO ml for water supplies (Fed. Wat. PCA 1968). Potential bacterial contamination exists wherever septic tanks are constructed on unsuitable soils (Reneau, et al., 1968). Pollu- tion from septic tanks is a major problem in the Black Creek watershed and its effects were detected at both low and high stream discharge. Contamination during low flow was severe at sewage outfalls and persisted throughout downstream areas at 500 FC/lOO ml.

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Dudley and Karr

Storm runoff increased downstream fecal pollution an order of magnitude. Scouring and transport of fecally contaminated sediment is suspected of causing this increase. In a study of salmonellae and fecal coliforms in bottom sediments, VanDonsel and Geldreich (1971) noted that movement of fecally contaminated sediments poses new water quality problems which must be considered. Thus, small unsewered communities create potential human health hazards within the immediate drainage at low flows and may substantially contaminate water for downstream uses during high flows.

When organic pollution is a major influence on the aquatic life of a stream it becomes important to determine the source and nature of the pollutant. On large rivers the sources are generally point discharges that are easy to identify, regulate, and control effectively. However, in smaller agricultural watersheds the problem becomes more com- plex due to the many sources of organic pollutants and their relationship to storm runoff events. Our findings suggest the various sources of organic pollutants in an agricultural watershed have differing impacts on the aquatic environment.

At low flow, septic tanks continually discharge organic pollutants into streams. Be- cause there is little dilution of the pollutant in the vicinity of the outfall, fish cannot tolerate these stream sections and the flora and invertebrate fauna are typical of grossly polluted waters. Further downstream the organic loading from septic tank sources adds to the organic matter of bottom sediments and in many areas this creates anaerobic sediments (pers. observ.). In this manner septic tank pollution affects the aquatic invertebrate community.

Typically organic pollution from other sources occurs only during storm runoff events. Decreasing FC/FS ratios during storm water runoff indicates substantial livestock sources of fecal pollution in the Black Creek watershed. Circumstantial evidence indicates that farms with unconfined livestock (pasture and barnlot) contribute more fecal pollution than confined livestock operations. Feachem (1974) observed a similar increase in the fecal contamination of storm water from unconfined livestock sources. Pollution from septic tank sources increases at high stream discharge because of the scouring and transport of fecally contaminated sediments. BOD samples taken during a storm event indicate high levels of organic pollution (15 mg BODlml). In a small drainage these high concentrations are maintained only for short periods of time and damage to aquatic life is probably minimal. However, total loading of organic pollutants from an agricultural watershed to a receiving river or lake increases significantly during storm events. For the Black Creek drainage an average BOD loading of 36.7 kg/km2 occurred during a single storm. Two agricultural areas in New Jersey were found to export up to 152 and 16.8 kg/day/km2 during high runoff periods (Yu, et al., 1975). It is clear that nonpoint water quality plans must consider the impact of agricultural sources of BOD on receiving rivers and lakes.

A fish kill caused by a discharge of liquid manure illustrates a severe pollution hazard. Confined livestock operations equipped with waste holding facilities are designed to pre- vent organic pollution of nearby streams. The vast majority of these systems accomplish this goal but modem livestock operations still represent a potential for gross organic pollution simply because of the large volume of wastes involved. Proper management of waste holding facilities is essential to avoid the consequences of accidental or intentional discharges of fecal material into streams. A few moments of carelessness can negate the value of several years of pollution control at a multitude of other sources.

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ACKNOWLEDGMENTS

Thanks to the Allen County Board of Health, Fort Wayne, and Pollution Control Systems, Lnc., Laotto, Indiana, for conducting laboratory studies. Isaac Schlosser commented on an earlier draft of this paper. This study was supported as a part of the U.S. Environmental Protection Agency PL 92-500, Section 108(a) demonstration project to Allen County Soil and Water Conservation District.

LITERATURE CITED

American Public Health Association, 1971. Standard Methods for the Examination of Water and Wastewater. Washington, D.C. (13th Edition).

Burwell, R. E., G. E. Schuman, R. F. Piest, R. G. Spomer, and T. M. McCalla, 1974. Quality of Water Discharged from Two Agricultural Watersheds in Southwestern Iowa. Water Resour. Res.

Faust, M. A., 1976. Coliform Bacteria From Diffuse Sources as a Factor in Estuarine Pollution. Water Res. 10:619627.

Feachem, R., 1974. Fecal Coliforms and Fecal Streptococci in Streams in the New Guinea Highlands. Water Res. 8:367-374.

Federal Water Pollution Control Administration, 1968. A Report of the Committee on Water Quality Criteria. US. Dept. of Interior, Washington, D.C.

Geldreich, E. E. and B. A. Kenner, 1969. Concepts of Fecal Streptococci in Stream Pollution. J. Water Pollut. Contr. Fed. 41:R336-352.

Geldreich, E. E., 1970. Applying Bacteriological Parameters to Recreational Water Quality. J. Amer. Waterworks Assn. 62: 113-1 20.

Harms, L. L., P. Middaugh, J. N. Dornbush, and J. R. Andersen, 1975. Agricultural Runoff Pollutes Surface Waters, Part 1. Water Sewage Works 122: 84-85.

Hynes, H. B. N., 1960. The Biology of Polluted Waters. Univ. Toronto Press, Toronto. Janzen, J. J., A. B. Bodine, and L. 1. Luszcz, 1974. A Survey of Effects of Animal Wastes on Stream

Pollution from Selected Dairy Farms. J. Dairy Sci. 57:260-263. Morrison, J., ef al., 1977. Environmental Impact of Land Use on Water Quality: Final Report of the

Black Creek Project. USEPA, Chicago, Illinois (4 Vols.). Reneau, R. B., Jr., J. H. Elder, Jr., D. E. Pettry, and C. W. Weston, 1975. Influence of Soils on

Bacterial Contamination of a Watershed from Septic Sources. J . Environ. Qual. 4:249-252. Smith, J. H. and C. L. Douglas, 1973. Microbiological Quality of Surface Drainage Water from Three

Small Irrigated Watersheds in Southern Idaho. J. Environ. Qual. 2:llO-112. Van Donsel, D. J. and E. E. Geldreich, 1971. Relationships of Salmonellae to Fecal Coliforms in

Bottom Sediments. Water Res. 5:1079-1087. Weidner, R. B., A. G . Christianson, S. R. Weibel, and G. G. Robeck, 1969. Rural Runoff as a Factor

in Stream Pollution. J. Water Pollut. Contr. Fed. 41 :377-284. White, R. K., 1972. Stream Pollution from Cattle Barnlot (feedlot) Runoff. Ohio Water Resources

Center, Project Completion Report No. 393X. 33 pp. (Also National Technical Information Ser- vice - PB-220-010.)

Yu, S. L., W. Whipple, Jr., and J . V. Hunter, 1975. Assessing Unrecorded Organic Pollution from Agricultural, Urban, and Wooded Lands. Water Res. 9:849-852.

10:359-365.

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