SA/TSB-14 A BENTHIC SURVEY OF FLAT CREEK AND THE SALT RIVER NEAR THAYNE, WYOMING AUGUST 1972 v TECHNICAL SUPPORT BRANCH SURVEILLANCE AND ANALYSIS DIVISION U. S. ENVIRONMENTAL PROTECTION AGENCY REGION VIII FEBRUARY 1973 ------- ¦ M SA/TSB-14 ^o/7 C-\ A1BENTHIC SURVEY OF ^SKQSSBBZBSKBB^ FLAT CREEK AND THE SALT RIVER NEAR THAYNE, WYOMING EPA Region VIII LIBRARY Denver, Colorado TECHNICAL SUPPORT BRANCH SURVEILLANCE AND ANALYSIS DIVISION U. S. ENVIRONMENTAL PROTECTION AGENCY REGION VIII November 1972 ------- TABLE OF CONTENTS Pa^e INTRODUCTION 1 METHODS AND MATERIALS 1 RESULTS AND DISCUSSION 1-9 SUMMARY 11 - i - ------- LIST OF FIGURES Page 1. Sampling Station Locations on Flat Creek and the Salt River near Thayne, Wyoming 2 LIST OF TABLES 1. Sampling Station Descriptions for Flat Creek and the Salt River, Thayne, Wyoming 3 2. Average Number of Benthic Organisms Collected from Flat Creek, near Thayne, Wyoming 4 3. Total Organic Carbon Levels at Flat Creek Sampling Stations 6 4. Total Phosphorus Levels at Flat Creek Sampling Stations 7 5. Total Nitrogen Levels at Flat Creek Sampling Stations 8 6. Dissolved Oxygen Levels at Flat Creek Sampling Stations 10 ii - ------- INTRODUCTION On August 29-30, 1972, at the request of the Enforcement Division of Region VIII, a benthic survey was conducted on Flat Creek and the Salt River near Thayne, Wyoming, by Ronald M. Eddy, a biologist from the Surveillance and Analysis Division, and Thomas Willingham from the Per- mits Branch. The survey was conducted to determine possible effects on Flat Creek and the Salt River of whey and raw sewage discharged from the Star Valley Dairy. The effluent of whey and sewage from the dairy and associated restaurant is discharged directly into Flat Creek. Approxi- mately two miles downstream from the effluent discharge, F.lat Creek flows into the Salt River (Figure 1). METHODS AND MATERIALS All quantitative samples were collected with a square-foot Surber sampler. Qualitative samples were collected both by removing organisms from selected rocks and debris by hand and with the use of a large dip net. All samples were preserved in 10% Formalin and transported to the Region VIII Biology Laboratory in Denver, Colorado, for processing. Figure 1 shows the location of each sampling station on Flat Creek and the Salt River. A description of the physical characteristics of each station is given in Table 1. RESULTS AND DISCUSSION The results of the Flat Creek benthic survey are shown in Table 2. All organisms were classified to the lowest taxinomic level possible. Two Surber samples were taken at all stations except FC-D-|-1 and FC-D-j-2. The quantity of organisms collected from the Surber samples taken at each station was averaged for each station and the values recorded in Table 2. For the purpose of this discussion, organisms will be classified accord- ing to .their sensitivity to organic pollution as pollution sensitive, pollution intermediate, and pollution tolerant. Pollution sensitive organisms are those which cannot withstand major reductions of dissolved oxygen or the smothering effect of sludge deposits often associated with organic pollution. With a moderate reduction of the dissolved oxygen concentration, the number and kinds of pollution sensitive organisms decrease with an associated increase in pollution intermediate and pollu- tion tolerant organisms. With still further reductions of dissolved oxygen, the pollution intermediate organisms decrease with pollution tolerant organisms becoming predominant. Of the major organisms collected from Flat Creek, EpkmexoptoAa (mayflies), T/UcopteAcL (caddis flies), and Plo.c.opt2Aa .(stoneflies) are examples of pollution sensitive organisms, while SimuJUdae. (blackflies) and Ckvionomlda.2. (midges) are examples of pollution intermediate forms. ------- FIGURE 1 Sampling Station Locations on Flat Creek and the Salt River near Thayne, Wyoming - 2 - ------- TABLE 1 Sampling Station Descriptions for Flat Creek and the Salt River, Tha.yne, Wyoming Station Location-^ Bottom Type Stream Width Physical Characteristics FC-U Flat Creek - 20 yards upstream of effluent. 75% 25% rock gravel 20 ft. Bottom completely covered with excessive growths of algae and aquatic plants. FC-Q Same as above - qualitative sample. FC-E Star Valley Dairy effluent taken directly from the weir box prior to discharge into Flat Creek. FC-Di-1 Flat Creek - 20 yards down- stream of effluent discharge, effluent side of stream. 75% 25% rock gravel 20 ft. Bottom, algae, and aquatic plants covered with thick layer of con- gealed whey. FC-D-] -2 Same as above - opposite side of stream. No deposits of congealed whey-- little or no lateral mixing of the effluent. fc-d2 . Flat Creek - 300 yards down- stream of effluent. 75% 25% rock gravel 20 ft. Large masses of congealed whe.y trapped in algae and aquatic plants bottom not completely covered. fc-d3 Flat Creek - 2 miles down- stream of effluent - 200 yards above confluence with Salt River. 50% 50% rock gravel 25 ft. Reduction of algal growths although still abundant. SR-U Salt River - 1/2 mile above con- fluence of Salt River and Flat Creek. o o lO "3- rock gravel 30 ft. No large growths of algae present. SR-D-j Salt River - 20 yards below confluence with Flat Creek. 50% 50% rock gravel 40 ft. sr-d2 Salt River - 3 miles below confluence with Flat Creek. 50% 50% rock gravel 40 ft. Both Surber samples taken on the edge of a small island in the middle of Salt River. ]_/ All samples were collected in shallow riffle areas. Two Surber samples were collected at each station, except FC-D-|-1 and FC-D-|-2. ------- TABLE 2 Average Number of Benthlc Organisms Collected from Flat Creek, near Thayne, Wyoming Benthic Organisms FC-U FC-Q-^ FC-D^-1 FC-D^-2 FC-D2 ^C-D^ EphtmeAopteAJZ Bat£U 6p. 78 Q 1 104 478 133 Eph.mtn.tZla. ¦&p. 2 Q - 11 2 1 PaAaltptopkltb-La. ip. - Q H2.ptaQQ.vuja. bp. Q - - TsUcopieAa Aga.pttuu> 4>p. 3 Q - 1 Hydn.opiyc.kt ip. 1 - - P&to.op£tn.a MmouAa t>p. 2 Q 1 - Hmipttna Cotuxidat - - Coltopttna. Einu.dat 14 Q - 72 1 2 V-ipteAa. SirnvJULdat 33 Q - 49 138 118 ChAA.onomi.doit 105 Q 5 67 546 1221 Empixlidat 3 Q - 2 TipuZidat 2 Q - 1 RkagioyUdat - - 1 Tabanidat - - 1 0&igocka.t£ti> 56 Q 1 75 57 6 A nntLiAa. H-OuicUnta. 56 Q - 39 16 2 Total Number of Kinds ... 12 13 4 9 7 9 Total Number per sq. ft.. . 355 - 8 419 1239 1486 ]_/ Qualitative sample - not used for computation of number of organisms per sq. ft. - 4 - ------- Fourteen different kinds of organisms were collected from the upstream control station (FC-U). Of the organisms collected, pollution sensitive mayflies [Ba&ta &p.) were the most prevalent, averaging 78 organisms per sq. ft. Although pollution sensitive caddis flies and stoneflies were collected, the small number taken indicate a minor role in the benthic population. Blackflies and midges averaged 33 and 105 organisms per sq. ft., respectively. The first downstream station (FC-D-j-1) illustrates the detrimental effect of the whey effluent on the benthic community. The first Surber sample (FC-Di-1) was taken on the same side of the stream as the effluent dis- charge. The bottom was covered with a thick layer of congealed whey for approximately 50 yards downstream from the discharge. The large reduc- tion of all kinds of organisms is likely the result of the smothering effect of the whey rather than any toxic quality. Lateral mixing of the whey had not been affected at the first downstream station. Consequently, the Surber sample taken from the side of the stream opposite the discharge (FC-D-2) did not show any detrimental effect of the whey. At the second downstream station (FC-D2)> 300 yards downstream of the discharge, large increases in the average number of mayflies, blackflies and midges were observed. Mayflies [Baztti tp.) increased from an average of 78 organisms per sq. ft. at the upstream control station to 478 organisms per sq. ft. Blackflies and midges increased from 33 and 105 organisms per sq. ft. at the control station to 138 and 546 organisms per sq. ft., respectively. The large increase in organisms was due to the enriching effect of the sewage portion of the effluent as evidenced by substantial increases in organic carbon, total nitrogen, and phosphorus levels downstream of the effluent (Tables 3, 4, and 5). The enriching effect of the effluent, however, cannot be classified as detrimental since not only the midges were increased but also the mayflies, a major fish food organism. At the last station sampled on Flat Creek (FC-D3), approximately two miles downstream of the discharge, the quantity of mayflies, blackflies, and midges was significantly higher than the upstream control station (FC-U). Mayflies [Bclq£aj> &p.) averaged 133 organisms per sq. ft. as com- pared to 78 organisms per sq. ft. at the control station. Blackflies and midges averaged 118 and 1221 organisms per sq. ft. as compared to 33 and 105 organisms per sq. ft., respectively, at the control station. Although all of the above organisms exhibited increases from the respective control station samples, only the midges experienced an increase in organisms per sq. ft. from the previous sampling station (FC-D2)• The decrease in may- flies and blackflies from the previous station indicates a lessening of the enrichment effect of the effluent due to dilution (Tables 3, 4, and 5). - 5 - ------- TABLE 3 Total Organic Carbon Levels at Flat Creek Sampling Stations Station Date Total Organic Carbon (mg/1) Average Total Organic Carbon Qnq/1) FC-U FC-E FC-D-j -1 FC-D -2 FC-D0 FC-D, 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 4.0 < 1 .0 1.0 4.0 <1 .0 3.0 220 7170 4670 3680 119 4970 No samples taken No samples taken 21 67 135 129 1 121 19 15 7 18 13 12 <2.3 3472 79 14 - 6 - ------- TABLE 4 Total Phosphorus Levels at Flat Creek Sampling Stations Station Date Total Phosphorus (rcg/U Average Total Phosphorus OM)' FC-U 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 0.05 0.07 0.05 0.06 0.02 0.02 0.045 FC-E 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 10.9 125.0 162.0 82.5 10.0 82.5 78.7 FC-D-j -1 No samples taken FC-D-j -2 No samples taken FC-D, 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 0.53 2.00 4.50 3.00 0.25 2.50 2.13 FC-D- 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 0.32 0.58 0.45 0.45 0.56 0.29 0.44 - 7 - ------- TABLE 5 Total Nitrogen Levels at Flat Creek Sampling Stations Station Date Total Nitrogen (fflq/1) Average Total Nitrogen (mg/1) FC-U 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 < 0.1 0.2 0.25 0.04 0.02 0.26 <0.14 FC-E 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 13.4 231 253 200 8 264 161.5 FC-D-, -1 No samples taken FC-D-, -2 No samples taken FC-D, 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 1.12 5.10 7.36 5.91 0.44 8.02 FC-D. 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 0.87 0.78 0.73 1 .08 1.32 1.20 0.99 - 8 - ------- A decrease in algal covering on the bottom, and consequent reduction in the actual amount of substratum sampled, may also account for part of the reduction in the number of organisms per sq. ft. The reason for the increase in the number of midges per sq. ft. from the previous up- stream station is not known. The only evident detrimental effect of the effluent was the smothering by the congealed whey at sampling station FC-D-j-1. Although congealed whey was observed downstream as far as sampling station FC-D3, no blanket- ing effect was evident as the congealed whey was isolated to small masses. Large reductions in dissolved oxygen concentrations, a possible detri- mental effect of whey discharges into water, were not realized. The dis- solved oxygen level was reduced from an average of 8.0 mg/1 at the upstream control station to an average of 5.7 mg/1 at sampling station FC-D2, a re- duction insufficient to produce gross detrimental effects in the benthic community. At sampling station FC-D:>, the dissolved oxygen concentration averaged 7.3 mg/1. Initial examination of the Salt River benthic samples evidenced pollution sensitive mayflies, caddis flies, and stoneflies, both upstream and down- stream of the confluence of Salt River and Flat Creek. As no detrimental effects of the effluent on the benthic community were observed at the farthest downstream station on Flat Creek (FC-D3), further processing of the benthic samples from Salt River to show detrimental effects on the benthic community below the confluence was deemed unnecessary. - 9 - ------- TABLE 6 Dissolved Oxygen Concentrations at Flat Creek Sampling Stations bissolved Oxygen Station Date Concentrations (rcg/P Average Dissolved Oxygen Concentrations (mg/1) FC-U 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 8.3 7.6 8.0 8.1 8.2 7.9 8.0 FC-E 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 3.6 1.7 1.5 2.9 4.9 1.4 2.7 FC-D]-1 No samples collected FC-D1-2 No samples collected FC-D, 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 6.0 5.4 5.4 6.1 5.7 5.4 5.7 FC-D, 8/28/72 8/29/72 8/30/72 8/31/72 9/01/72 9/02/72 7.5 7.4 8.2 7.7 5.2 7.5 7.3 - 10 - ------- SUMMARY 1. The Star Valley Dairy, Thayne, Wyoming, discharges whey and raw sewage into Flat Creek, which then flows into the Salt River. 2. On October 29-30, 1972, members of the Region VIII Environmental Protection Agency conducted a benthic organism survey on the Flat Creek and the Salt River to determine possible effects of the Star Valley Dairy effluent on the benthic invertebrate community. 3. The effluent had a detrimental effect on the benthic community in Flat Creek due to a smothering blanket of congealed whey desposited on the bottom. The blanketing occurred only on the effluent side of the stream and extended for approximately 30 to 40 yards down- stream from the discharge point. 4. Although masses of congealed whey were observed 300 yards downstream from the discharge, no blanketing of the bottom occurred. The three major constituents of the benthic population--mayflies, blackflies, and midges—increased greatly from the upstream control station due to the enrichment effect of the sewage portion of the effluent. 5. At the last downstream station on Flat Creek, the quantity of may- flies and blackflies, although greatly reduced from the previous upstream station, still exceeded the control station samples. 6. No detrimental effect of the effluent was observed at the farthest downstream sampling station on Flat Creek. 7. Dissolved oxygen concentrations were not greatly reduced in Flat Creek due to relatively high dissolved oxygen levels of the effluent. 8. Initial examination of the Salt River benthic samples showed pollu- tion sensitive mayflies, caddis flies, and stoneflies evident both upstream and downstream of the confluence of Flat Creek and the Salt River. As no detrimental effects of the effluent on the benthic community were observed at the farthest downstream station on Flat Creek (FC-D3), further processing of the benthic samples from the Salt River was deemed unnecessary. - 11 - ------- |