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HomeMy WebLinkAboutNC0025534_Report_19860515NPDES DOCIMENT !;CANNIN` COVER SHEET NPDES Permit: NC0025534 Hendersonville WWTP Document Type: Permit Issuance Wasteload Allocation Authorization to Construct (AtC) Permit Modification Complete File - Historical Report Speculative Limits Instream Assessment (67b) Environmental Assessment (EA) Permit History Document Date: May 15, 1986 Miss document ifs printed on reuse paper - ignore any content on the reszerse side DIVISION OF ENVIRONMENTAL MANAGEMENT May 15, 1986 MEMORANDUM TO: George T. Everett Forrest Westall Dennis Ramsey FROM: Steve W. Tedder SUBJECT: Hendersonville WWTP/Intensive Toxics Evaluation Henderson County Staff of the Technical Services Branch have conducted intensive toxics, biological and chemical evaluations at the Hendersonville WWTP. This evaluation was conducted during September, 1985. The attached report details the results and conclusions as well as recommended actions. If there are questions, please contact Ken Eagleson or myself at (919) 733-5083 or Larry Ausley at 733-2136. Attachment SWT/gh cc: Ken Eagleson Larry Ausley Doug Finan Jay Sauber Meg Kerr Jimmy Overton Central Files 69 Hendersonville WWTP Toxicity Examination NPDES#0025534 C inuuni1,,,,,,,,,,, North Carolina Department of Natural Resources & Community Development /1C/3/LF ALI Bioassay and Biomonitoring LABORA TOR)' [inhIIIItII) 111111„1111 333'333 33k""' »>zz3;itii$22 >; 3k*"""',433; ; `z;z;zzi33W OM' NORTH CAROLINA DEPARTMENT OF NATURAL RESOURCES AND COMMUNITY DEVELOPMENT WATER QUALITY SECTION 0 HENDERSONVILLE WWTP TOXICITY EXAMINATION NPDES NO. NC0025534 May 1986 NORTH CAROLINA DEPARTMENT OF NATURAL RESOURCES AND COMMUNITY DEVELOPMENT DIVISION OF ENVIRONMENTAL MANAGEMENT WATER OUALITY SECTION TABLE OF CONTENTS Page List of Figures and Tables Introduction. 1 Toxicity Examination 4 Chemical Sampling 8 Benthic Macroinvertebrate Analysis 15 Conclusions 20 Recommendations 23 Appendix 25 Daphnia pulex,Test Procedure 26 96 Hour Flow -Through Test Procedure 27 Ceriodaahnia Reproduction Test Procedure 29 Benthic Macroinvertebrate Procedure 30 List of Definitions 32 LIST OF FIGURES Page Figure 1. Schematic Diagram of Hendersonville WWTP 3 Figure 2. Seven Day Ceriodavhnia Mean Cumulative Reproduction 6 Figure 3. Seven Day Ceriodaohnia Mortality 7 Figure 4. Study Area and Sampling Sites 14 LIST OF TABLES Page Table 1. 96 Hour Fathead Minnow Mortality 4 Table 2. Sampling Site Descriptions 9 Table 3. Results of Chemistry Analyses 10 Table 4. Benthic Macroinvertebrate Taxa Richness Values 16 Table 5. Benthic Macroinvertebrates Collected 17 INTRODUCTION An on -site toxicity examination was conducted at the Hendersonville WWTP (NC0025534) from September 23-28, 1985. This facility, located in Henderson County, treats domestic waste, combined stormwater and industrial wastewater from nearby facilities. These industries are permitted to discharge approximately 174 thousand gallons of waste -water each day to the Hendersonville WWTP for treat- ment. This would account for 7.6% of the facility's permitted flow. Facility operators estimate the actual average flow contributed by industrial users at 3.5% of the facility's flow. Individual contributions listed by the last avail- able evaluation are as follows: Industry Category Flow General Electric Transformer manufacturing 90,000 GPD Kimberly Clark Corp. Textiles 60,000 GPD Spinning Wheel Rugs Woven carpets and rugs 10,000 GPD Belding Corticelli Thread Mills 7,500 GPD Federal Paper Board Paper products 4,000 GPD Consolidated Aluminum Corp. Primary aluminum products 2,000 GPD Southern Agricultural Insecticides Pesticide production 100 GPD The wastewater generated from textile and laundry processing represents a significant portion (44.5%) of the total flow from industrial contributors. Be- cause batch processing (and subsequently batch discharging) is normal operating procedure for these industries, the WWTP is faced with handling batches (or slugs) of wastewater on an irregular basis. In addition to receiving these industrial contributions, the facility accepts wastewater from septic tank clean- ing companies. This document details findings of chemical and biological samp- ling, including the following: 1. 48 hour static bioassay using Daphnia pulex on effluent samples to determine acute toxicity. 2. 96 hour flow -through acute bioassay using Pimephales promelas (fathead minnows) performed on effluent collected at an effluent stream access opening below the final clarifier prior to chlorination. 3. Chemical samples collected from effluent, influent, and the receiving stream. 4 Collection and analysis of macroinvertebrate samples to determine the impact of the effluent on the receiving stream populations. 5 Seven-day Ceriodaphnia reproduction test to assess sub -lethal chronic toxicity. The Hendersonville WWTP discharges to Mud Creek (Class "C") approximately 8900 m upstream of Mud Creek's confluence with the French Broad River in the French Broad River Basin. The 7010 flow for Mud Creek at the discharge site is 40 cfs. On July 9, 1981, the City of Hendersonville was granted a Special Order by Consent (SOC) to allow its wastewater treatment plant to receive more waste and thus increase its discharge flow above its flow limit. Since that time the SOC has been amended to further increase flow and allow for construction. Con- struction on expanded facilities has been partially completed. The last amended SOC expired November 15, 1985_ A new permit was obtained on this same date. Permitted flow was expanded to 3.2 MGD. This study was performed during the period in which the SOC was in effect. The permitted flow, under the Special Order by Consent (SOC) of the facility was 2.9 MGD. The permitted flow prior to the SOC was 2.5 MGD. During 7010 low stream flow and SOC permitted effluent flow conditions, the effluent from the Hendersonville WWTP comprised 10.1% of the receiving stream. A yearly summary of permit compliance data indicates non- compliance with previous permit limitations in levels of flow, BOD, and fecal coliform. During the period of testing, the facility was operating under the SOC which allowed a flow of 2.9 MGD, B0D6 of 30 ppm, total suspended solids of 30 ppm, and a fecal coliform limit of 1000/100 ml. BOD and fecal coliform levels were not in compliance with the limitations included in the SOC. Waste treatment processes include influent screening, primary settling, trickling filter, final clarifier, chlorine contact chamber, and sludge drying beds. A schematic representation of the Hendersonville WWTP appears in Figure 1 FIGURE 1. Hendersonville WWTP Schematic Diagram. Influent Station 02A (Flow Prior to Hydrasieves) r Chlorination Building STATION 02 - Bioassay Sampling fOir Point Mobile Lab Location PRIMARY CLARIFIER TRICKLING FILTER (Pump Station J O + l r ' / r __l r r r r r r \ ,\ / \'r \'. r \ r \ r♦,,\ ,\ ('r 1 \ r 1 r \ r\ , ,J , J J r r� r r r r r r ,, ♦ \ 1 1 % \ 1 h 1 ♦ ♦ \ \ ♦ • / r / r r , / / / \ 1, \ \ \ \ \ \ \ \ Discharge to Mud Creek lir -3- SECONDARY CLARIFIER CHLORINE CONTACT CHAMBER TOXICITY EXAMINATION The on -site toxicity examination was performed as a result of a series of Daphnia pulex 48 hour static bioassays conducted April 27, 1984, April 25, 1985, and July 25, 1985. The resulting LC6o vales of these tests were 52%, none, and 27% respectively. The LC50 value is the effluent concentration causing mortality to 50% of the test organisms. The flow -through bioassay was performed on effluent collected prior to chlorination, from an effluent stream access opening just below the final clar- ifier. Dilution water for this test was obtained from Clear Creek at SR-1006 in Henderson County near Hendersonville. This stream was selected after determining its suitability using the seven-day Ceriodaphnia reproduction bioassay. The 96 hour flow -through bioassay was initiated at 11:30 A.M. on September 24, 1985. The test organisms, fathead minnows, were 45-53 days old and were obtained from cultures maintained by the Aquatic Toxicology Laboratory in Cary, N.C. These fish were acclimated to Clear Creek water on September 19, 1985 prior to testing. The minnows were transferred to test chambers containing dilution water approximately 19 hours prior to test initiation. Ten fish were placed in each chamber with replicates of six concentrations and a control (dilution water). The toxicant delivery system cycled 268 times during the course of the test. The final 96 hour mortality data is listed in Table 1 Table 1. 96 Hour Fathead Minnow Mortality Effluent Concentration (%) Mortality (%) 0 0 5 0 10 0 25 0 50 0 75 0 100 5 Fish mortality in 100% effluent was not significantly different from control mortality. The 96 hour Fathead minnow LC60 value was determined to be greater than 100% effluent since no significant mortality was noted during the 96 hour test period. Daphnia pulex bioassays were conducted on -site for both influent and effluent samples. A forty-eight hour LC60 value of <5% (24 hour LC60 = <5%) was determined using an instantaneous grab of influent on September 26, 1985_ The effluent bioassay, using a twenty-four hour composite sample, yielded an LC60 value of 14% (24 hour LC60 = 15%). A portion of the unused composite effluent sample was set aside in an open container and aerated. After 96 hours, a twen- ty-four hour bioassay was conducted to determine the persistence of toxicity in the aged and aerated effluent. No mortality was observed in any of the effluent concentrations, indicating no persistence of toxicity to D. pulex. A seven-day Ceriodaohnia static replacement bioassay was performed on dilu- tions of effluent in order to assess sub -lethal toxicity. This test was initi- ated on -site at the Hendersonville WWTP on September 23, 1985 and was concluded at the Aquatic Toxicology Laboratory on September 30, 1985. Dilution water for this test was obtained from Clear Creek near Hendersonville. Mean cumulative reproduction of this test is presented in Figure 2. At the end of the seven-day test period, a significant reduction in reproductive success was exhibited at the 10% effluent concentration. Reproduction similar to that of the controls was found in the 0.01%, 0.1%, and 1.0% effluent concentrations. In all concentra- tions of 10% and greater, complete organism mortality occurred. Also, it was noted that only five (of ten) adults in the 10% concentration bore young before 100% mortality was reached by the fifth day. A 168-hour LC60 of 3.2% effluent was calculated for this test (see Figure 3). —5— Figure 2. Seven Day Ceriodaphnia Mean Cumulative Reproduction Hendersonville WWTP -6- Figure 3. Seven Day Ceriodaphnia Mortality. Hendersonville WWTP 100 R T 0 x 1 c A N T 10 V 0 L U M E 1 LOG -CONCENTRATION VS 9 MORTALITY 0 10 20 30 40 50 60 R MORTALITY LC50 =3.2% _7_ . 70 80 g0 100 The Hendersonville WWTP had performed three self -monitoring bioassays during the months of February, March and May 1985. Resulting LC6o's of 86% and 76.5% effluent were reported for March and May respectively. A partial mortality of 45% in the 100% effluent concentration was reported for February 1985. CHEMICAL SAMPLING A series of chemical samples was collected during this investigation and sent to the Division of Environmental Management's Central Laboratory for analysis (Table 3). Descriptions of the sampling stations are found in Table 2. All samples were collected as instantaneous grabs with the exception of Station 02 samples (toxicity sampling point) which were taken as 24 hour composites. Metals analyses of effluent samples reported zinc concentrations of 110 ug/I on September 26 and 200 ug/l on September 28. At these concentrations and 7010 con- ditions, the concentration in the receiving stream would average 15.65 ug/I at flows allowed under the SOC and assuming a concentration of zero upstream. At average stream flow and average facility flow, the instream concentration of zinc is estimated to be 2.68 ug/I. The N.C. Water Duality Action Level for zinc is 50 ug/1. Zinc concentrations of 60 ug/I and 40 ug/I were detected in the influent on September 26 and September 28 respectively. All other sites had concentra- tions of <20 ug/I on both sampling dates, which is the lower reporting limit for zinc. Metals analyses reported copper concentrations in the effluent of 41 ug/I on September 26 and 70 ug/I on September 28. At low flow conditions these would indicate an instream average concentration of 5.61 ug/I of copper, again assuming SOC flow and a background concentration of zero. Influent, upstream, downstream and dilution water sites were found to have <20 ug/I of copper on both sampling dates, which is the lower reporting limit. At average stream flow and average facility flow, the instream concentration of copper is estimated to be 0.96 ug/I. The N.C. Water Quality Action Level for copper is 15 ug/I. Table 2. Sampling Sites Station 01 Mud Creek at SR-1508 approximately 475 meters upstream of the discharge at the Hendersonville WWTP. At this point the stream is approximately 10 meters wide and 1 meter deep with a sandy substrate also containing some rubble and mud. Station 02 Hendersonville WWTP effluent collected from an effluent stream access opening just below the final clarifier, but prior to chlorination. This is the bioassay sampling point for the Daphnia pulex static tests. Ceriodaphnia reproduction/chronic tests, and the flow -through bioassay. Station 02A Hendersonville WWTP influent collected immediately prior to the bar screens. Station 028 Hendersonville WWTP effluent collected at the step aerator at the end of the chlorine contact chamber. Station 03 Mud Creek approximately 100 meters below the Hendersonville WWTP discharge. At this point, the stream is from 5-10 meters wide and from 0.5-1.5 meters in depth with a sandy substrate. Station 04 Clear Creek at SR-1006 near Hendersonville. Here the substrate is sand and muddy sand with a small amount of gravel. The stream is about 0.5 meter in depth and approximately 5 meters wide. This is the dilution water site for all investigation bioassays. Total suspended residue levels in the effluent were 68 mg/I and 78 mg/1 on September 26 and September 28 respectively. These values would indicate possible exceedances of permitted effluent limitations (30 mg/I monthly average and 45 mg/1 weekly average) if concentrations remain at encountered levels. On September 26 the total ammonia nitrogen level in the effluent was 11 mg/I and on September 28 it was 18 mg/I. On both sampling dates ammonia nitrogen lev- els were higher in the effluent than in the influent; on September 26 concentra- tions increased from 10 to 11 mg/I, and on September 28 ammonia nitrogen increased from 5.8 to 18 mg/I. When wastewater is sufficiently aerated and the nitrogen cycle functioning efficiently, ammonia -nitrogen should be oxidized to Table 3. Results of Chemistry Analyses DESIGN FLOW (MGD) 2.9 AVERAGE DISCHARGE (MGD) 2.04 AVERAGE STREAM FLOW (CIS) 180 7Q10(CFS) 40 Chemical/Physical UNITS Water Quality Ste 01 Sta 02 Sta 02A Ste 03 Sta 04 Analyses Standards 850928 850928 850928 850928 850928 r BOD PPM COD PPM 8 270 400 18 8 Coliform: MF Fecal /100 ml Residue TOTAL PPM 100 320 1601 92 53 volatile PPM 40 150 891 21 15 fixed PPM 61 160 741 71 38 Residue SUSPENDED PPM 8 78 40! 7 <1 volatile PPM 6 60, 40 6 <1 fixed PPM 1 18 0 1 <1 pH (standard units) 6.0-9.0 6.9 71 6.6 6.6 6.4 Acidity PPM 3 33 25 5 6 Alkalinity PPM 331 94 48 27 19 Arsenic: Total PPB FormaldehOe PPM Hardness PPM 18 24 22 18 14 Phenols PPB <5 7 5 <5 Specific Conductance uMhos/cm 73 340 170 77 55 NH3 PPM 0.04 18 5.8 0.95 0.01 TKN PPM 0.2 19 7.1 1.1 0.2 NO2,NO3 PPM 0.68 0.15 0.04 0.63 0.3 P. total PPM 0.05 7.4 1.91 0.35 0.03 Aluminum PPB 200 1000 200 500' <100 Cadmium PPB 2 <20! <20 <20 <20 <20 Chromium PPB 50 <50 <50 <50 <50 <50 Copper PPB 15(ALt) <20 70 <20 <20 <20 Iron PPB 1000(AL) 700 2000 13001 800! 200 Mercury PPB 0.2 <.2 <.2 <1 <.2 <_2 Manganese _ PPB 60 100 90 60 <50 Nickel PPB 50 <100 <100 <100 <100 <100 Lead PPB 25 <100 <100 <100 <100 <100 Zinc PPB 50(AL) <20 200 40 <20' <20 Tributyltin Hydride PPB <0.03 Chloroform PPB 6.2 Scan Base/Neutral j ND Trichloroethane PPB 2 Trichloroethene PPB t 0.4 Tetrachloroethene PPB 1 3.1 j Chlordane PPB , `{ 6.81 4-(1,1,3,3Tetramethyl butyl )phenol PPB l 11 Unidentified peaks * 21 i -10- Table 3. Results of Chemistry Analyses PERMITTED FLOW (MGD) 2.9 AVERAGE DISCHARGE (MGD) AVERAGE STREAM FLOW (CFS) 7Q10 (CFS) 40 Chemical/Physical UNITS Water Quality Sta 01 Sta 02 Sta 02A Sta 03 Sta 04 Analyses Standards 850926 850926 850926 850926 850926 BOD PPM 1.1 40 85 1.4 1.5 COD 1 PPM 7 220 310 16 5 Coliform: MF Fecal /100 ml 740 180000 2800000 Residue TOTAL PPM J 761 250 220 84 70 volatile j PPM 30 120 130 26 28 fixed PPM 46 130 96 58 42 Residue SUSPENDED PPM 19 68 63 15 4 volatile PPM 4 50 57 4 2 fixed PPM 15 18 6 11 2 pH (standard units) 6.0-9.0 6.9 7.31 6.7 6.9 6.7 Acidity PPM 11 26 69 17 17 Alkalinity PPM 20 69 70 241 20 Arsenic: Total PPB <10, I Formaldehyde PPM 0.4 1 1 Hardness PPM 20 26 22 181 14 Phenols PPB <5! 91 12 <51 Specific Conductance uMhos/cm 61 320 230 81 56 NH3 PPM 0.03 111 10 0.72! 0.01 TKN PPM 0.2 12 12 1 0.2 NO2,NO3 PPM 0.51 0.15 0.01 0.48 0.36 0.35! 0.03 P. total PPM 0.06 5.6 31 Aluminum PPB 700 800 400 600 200 Cadmium PPB 2 <2.0 <2.0 <2.0 <2.0 Chromium PPB 50 <5.0 <5.0 <5.0 <5.0 Copper PPB 15(ALt) <2.0 41 18 2.8 <2.0 Iron PPB 1 1000(AL) 900 1500 1500 900 200 Mercury PPB 0.2 <.2 <.2 <.21 <_2' <.2 Ma nonese PPB 70, 1001 100 70 <50 Nickel PPB 50 <10 <101 <10 <101 <10 Lead PPB 25 <10 11. <10 25 <10 Zinc PPB 50(AL) 4.6 110! 60 7.7 <2.0 Magnesium PPM 61 320 230 81 56 i i I 1 1 nitrate -nitrogen', and ultimately there should be a decrease in ammonia -nitrogen as waste is processed. The amount of ammonia -nitrogen in wastewater is important because it can be toxic to aquatic organisms in the un-ionized (NH,) form. The percentage of un-ionized ammonia in a water sample is dependent on temperature and pH. The temperature and pH of the effluent on September 16 was 22.0°C and 7.3 S.U. • lam'- v� on September 28 was 17.5°C and 7.0 S.U. respectively. Consequently, the amount A' \ of unionized ammonia was 0.33% or 0.58 mg/I, which corresponds to an instream concentration, at low flow, of 0.006 mg/I. This level of unionized ammonia j°--4` should not cause detrimental effects to the receiving stream. t ; 1 The influent sample collected September 26, 1985 had three unidentified sample revealed 66 ug/I of total alkanes and 2.2 ug/I of tetrachloroethene (a ,, 2 b-tt i - a,. M I t ., a ( CSRSA2). Chloroform, an alkyl halide and an EPA hazardous waste, hazardous respectively. Under those conditions 0.93% (of 11 mg/1) or 0.10 mg/1 was in the toxic un-ionized form. The instream concentration of ammonia in Mud Creek during low flow conditions is determined by mass balance to be 0.01 mg/l (assuming back - round concentration equals zero). The water temperature and pH of the effluent organic peaks, ranging from 11-34 ug/liter. Organic analyses of the influent substance and priority toxic pollutant' was detected at a level of 9.4 ug/I. Caffeine, a cyclic amide and constituent of beverages and medicines" was detected ' California State University -Sacramento. 1980. Operation of Wastewater Treatment Plants: A Field Study of Training Program. Vol III. 2nd Ed. EPA Grant No. T900690010. Citation found on page 102. 2 Chemical Substances Requiring Special Attention. 1985 .0208(b) of N.C. NRCD, DEM Administrative Code Section: 15 NCAC 28 .0200. 8 Sittig, Marshall. 1981. Handbook of Toxic and Hazardous Chemicals. Noyes Publ., Park Ridge, New Jersey. Verschueren, Karel. 1983. Handbook of Environmental Data on Chemicals. 2nd Ed. at a level of 15 ug/I. 1,1-dichloroethane, a constituent of adhesives, and a component of synthetic fibers, was found at a level of 1.3 ug/I. This compound is a CSRSA'. The 96 hour bluegill sunfish LC6q for this compound is 550 mg/I3. 6.3 ug/1 of 1,1,1-trichloroethane was detected in the sample. This compound is an EPA hazardous waste and priority toxic pollutant2. The 96 hour fathead minnow flow -through LC60 for 1,1,1-trichloroethane is 52.8 mg/I2_ The September 28 influent sample contained 6.2 ug/I of chloroform, 2.0 ug/I of 1,1,1-trichloroethane, 0.40 ug/I of trichloroethene (a CSRSA2), and 3.1 ug/I of tetrachloroethene. Organic analyses revealed effluent concentrations on September 26 of 2.6 ug/I of chloroform, 1.4 ug/I of 1,1-dichloroethane, 0.71 ug/I of 1,1,1-trichloro- ethane, and 0.12 ug/I of tetrachloroethene. Analyses of the September 28 efflu- ent revealed 1 ug/I of total alkanes, 2.5 ug/I of chloroform, and 11.0 ug/I of 1,1,3,3-tetra methyl butyl phenol. No toxicity data could be located for this compound. Chlordane, a broad spectrum cyclodiene insecticide, was detected at a level of 6.8 ug/I_ It has been used extensively over the past 30 years for termite control, and as a general insecticide in agricultural applications. It is designated an EPA hazardous waste and priority toxic pollutant'. At this concentration (6.75 ug/l) and 7010 conditions, the concentration in the receiving stream would be 0.682 ug/I. At average stream flow and SOC permitted facility flow, the instream concentration of chlordane is estimated to be 0.162 ug/l. Both predicted values represent exceedances of the N.C. Water Quality Ac tuft 1-+m-i-1 for chlordane of 0.004 ug/I_ Acute toxicity values located for chlordane are listed as follows: ' Listed previously as 2 2 Listed previously as 3 Figure 4. Hendersonville WWTP Study Area and Sampling Sites Organism Test Duration LC Daphnia pulex (water flea) 48 hour 29 ug/1' Leoomis macrochirus (bluegill) 96 hour 22 ug/I' Pimephales promelas (fathead minnow) 96 hour 36.9 ug/I' Satmo oairdneri (Rainbow trout) 96 hour 42 ug/la Ictalurus punctatus (Channel catfish) 96 hour 6.7 ug/Ia BENTHIC MACROINVERTEBRATE ANALYSES Benthic macroinvertebrates were collected on September 25-17, 1985. Sta- tions 01 and 03, upstream and downstream of the Hendersonville discharge on Mud Creek, correspond to chemical sampling sites. A reference site, Station 04B on the Mills River, was also sampled. Data from this investigation is summarized in Table 4 and all taxa collected are listed in Table 5. Benthic macroinvertebrates were sampled using a standardized qualitative collection technique (DEM 1983). The primary output from this collection tech- nique is a tabulation of taxa richness, i.e., the number of different kinds of animals present. Unstressed streams and rivers always have high taxa richness. Various types of pollution will reduce or eliminate the more intolerant species, producing lower taxa richness values. In-house criteria have been developed to relate taxa richness to five water quality ratings or bioclassifications: Excel- lent, Good, Good/Fair, Fair and Poor. Taxa richness values are calculated both both for all species (ST) and for the more intolerant groups (Ephemeroptera, Plecoptera, Trichoptera: SEAT). The distribution and abundance of various pol- lution "indicator" species also can be utilized to deduce changes in water quality. ' Listed previously as 2. a Mississippi Cooperative Extension Service. 1984. Agriculture chemical toxicity to selected aquatic animals: bluegill, channel catfish, rainbow trout, crawfish, and freshwater shrimp. Miss. State Univ., Coop. Ext. Serv. Publ. No. 1455. 24 pp Analysis of benthic macroinvertebrate populations in Mud Creek indicate Poor water quality above and below the Hendersonville WWTP discharge point. However, there were significant decreases in both total taxa (51 upstream to 30 down- stream) and intolerant taxa (9to 3). In addition, Cricotopus bicinctus and Polypedilum illinoense, taxa very tolerant to toxic stress, were more abundant below the discharge. These population trends indicate the Hendersonville efflu- ent has an impact on Mud Creek. The Mills River site was rated Good based on total taxa richness of 91 and intolerant taxa richness of 37. Mills River was sampled 1.25 miles downstream during the 1984 Benthic Macroinvertebrate Ambient Network (BMAN) and similar taxa richness values were found (91-total, 45-intolerant). Water quality as indicated by benthic macroinvertebrate community analysis was Poor at Mud Creek sites above and below the Hendersonville WWTP discharge. Lower taxa richness values and increased abundance of toxics tolerant taxa at the downstream site indicate the Hendersonville WWTP discharge is further degrading poor water quality conditions in Mud Creek. Table 4. Taxa Richness of Benthic Macroinvertebrate Groups from Mud Creek and the Mills River, Henderson County. Mud Creek Mills River 01 03 04B Ephemeroptera 7 2 18 Plecoptera - - 6 Trichoptera 2 1 13 Odonata 5 5 4 Coleoptera 6 2 3 Megaloptera 2 - 2 Crustacea 1 - 1 Mollusca 1 1 2 Diptera: Misc. 4 3 10 Diptera: Chiron. 17 10 28 Oligochaeta 5 5 3 Other 1 1 1 Subtotal, EPT 9 3 37 Taxa Richness 51 30 91 Bioclassification Poor Very Poor Good Table 5. Benthic Macroinvertebrate Taxa Collected from Mud Creek and the Mills River. Henderson County, North Carolina. September 1985. (A = Abundant, >10 specimen; C = Common, 3-9 specimen; R = Rare, <3 specimen) Mud Creek Mills River O1 01 04B EPHEMEROPTERA Stenonema modestum A R Stenonema pudicum A Stenonema Ithaca C Stenacron interpuctatum R Stenacron pallidum R Epeorus rubidus C Heptagenia spp. R Ephemerella bicolor R Ephemerella hispida C Ephemerella wayah R Ephemerella deficiens C Neoephemera pupurpea A Baetisca carolina A Baetisca gibbers C Isonychia spp. A Baetis intercalaris A Baetis pluto C C Baetis frondalis R Baetis propinguus R Baetis flavistriga R R Pseudocloeon sp. C A Paraleptophlebia A Hexagenia sp. R PLECOPTERA Allonarcyes A Acroneuria abnormis A Peltoper'la A Allocapnia C Paragnetina immarginata C Isogenoides hansoni R TRICHOPTERA Oligostomis pardalis C Brachycentrus A Dolophilodes A Ceraclea ancylus R Hydatophylax argus C Neophylax C Rhyacophila torva R Rhyacophila fuscula C Rhyacophila atrata R Cheumstopsyche R A Hydropsyche sparna A Hydropsyche bronta C Hydropsyche betteni A C Hydropsyche morosa R Mud Creek Mills River 01 03 04B ODONATA Goniphus C R C Boyeria vinosa C A C Cordulegaster R Argia C C Enallagma C R. Calopteryx C A C COLEOPTERA Peltodytes R Hydroporus R Ancyronyx varigatus A A Macronyrchus glabratus A Promoresia tardella R Helichus A 0ptioservus C Trepisternus R Agabus R Psephenus herricki A MEGALOPTERA Corydalus cornutus R Nigronia serricornis C Sialis R R CRUSTACEA Cambarus C C MOLLUSCA Ferrissia rivularis C R A Elimia A DIPTERA: MISC. Simulium vittatum A A A Simulium (Phosterodoros) C Tipula C C R Hexatoma R R Atherix lantha C Dixa C Palpomyia C Chrysops R R Dicronota R Antocha R Atrichopogon C DIPTERA: CHIR0N0MIDAE Thienemanniella C C Corynoneura R R Synorthocladius R Paraphaenocladius sp. 1 C Parachaetocladius C Brillia R Cricotopus/Orthocladius sp. 1 A A* C C/O sp. 3 R C/O sp. 6 R C C/0 sp. 13 R C/0 sp. 20 R C/O sp. 54 R Nannocladius R Parakiefferiella triqueta R Parakiefferiella sp. 4 R -18- Mud Creek Mills River O1 03 04B DIPTERA: CHIRONOMIDAE tCont.) Rheocricotopus sp. 1 A A Rheocricotopus sp. 2 R Stenochironomus R R Chironomus C Parachironomus monochromus R Polypedilum illinoense A A* Polypedilum fallax R C Polypedilum aviceps C Polypedilum scalaenum C Saetheria tylus R Paratendipes C Cryptochironomus fulvus R Phaenopsectra sp. 2 C Phaenopsectra sp. 4 C Microtendipes sp. 3 C Rheotanytarsus A C C Tanytarsus R C Conchapelopia R Natarsia R R Procladius R Ablabesmyia ornata C C Labrundinia pilosella R Sympotthastia R Pagastia C Potthastia gaedi A Odontomesa fulva R OTHER TAXA Mooreobdella tetragon C Belastoma R Acaria C Total Taxa Richness 51 30 91 CONCLUSIONS Ceriodaphnia dubia was the most sensitive organism exposed to the effluent, with Daphnia pulex next, and fathead minnows being least sensitive. It has been the experience of the DEM that cladocerans (Ceriodaphnia and Daphnia) have often been more sensitive to complex effluents than the fathead minnow. Toxicity tests performed on the effluent prior to this study seem to indi- cate a moderate degree of toxicological variability based on 48 hour D. pulex static tests. Results of these ranged from None to 27% for DEM tests, and from P45 to 76.5% for 3 self -monitoring tests performed for the facility. On -site Ceriodaphnia reproduction data display reproduction suppression at an effluent concentration of 10%, while 1% shows no significant effects on the population. Effluent constituents that may contribute to the observed toxic effects would include zinc concentrations of 110 and 220 ug/I and copper concentrations of 41 and 70 ug/I, though these would not translate to concentrations of concern when diluted by the receiving stream. The level of effluent chlordane (6.75 ug/I) and predicted instream concentrations during 7010 conditions (.6868 ug/I) is of concern as the predicted concentration exceeds the N.C. water quality standard (.004 ug/l) by a factor of 172. Although not present in the receiving stream in an acutely toxic concentration, the possibility of adverse effects through chronic exposure can not be ruled out, especially if chlordane is regu- larly present at measured effluent concentrations. Because of the environmental persistence of this compound, its bioaccumulative potential, and the possibility of its being a human carcinogen', efforts to minimize its discharge should be undertaken. It is currently registered for use in North Carolina only as a con- trol for subterranean termites. ' Train, R.E. 1974. Pesticide products containing heptachlor or chlordane: Intent to cancel registrations, Federal Register, Vol 39, No. 229, Tues., Nov. 26, 1974. p 41299. The occurrence of 1,1,3,3-tetramethyl butyl phenol in the September 28 effluent is possibly the result of textile processing and handling. The detec- tion of this compound (and others) on only one sampling date illustrates the fact that slugs of wastewater with varying composition are discharged to the facility. Whether the two sets of instantaneous grab samples taken during this study pro- vide a definition of the typical water chemistry is difficult to ascertain. Although 24 hour composite samples tend to underestimate peak concentrations of chemical constituents, and thus do not indicate peak toxic effects, this sampling regime has been chosen for effluent characterization to obtain more represent- ative samples of the waste stream over time (as compared to grab samples). Other effluent constituents, both identified (i.e. chlordane and 1,1,3,3-tetramethyl butyl phenol) and unidentified, may contribute to the whole effluent toxicity through chemical interactions. Results of chemical analyses of receiving stream samples indicate that no significant increase in analyzed parameters was occurring downstream of the Hend- ersonville WWTP discharge as compared to upstream concentrations. When correlating on -site test results (during the SOC period) with predicted instream waste concentrations (IWC) during low flow conditions (IWC = 10.1%) and during average flow conditions (IWC = 2.4%) it is predicted that the more sensi- tive organisms are being impacted. A 168 hour LC60 of 3.2% indicates that during low flow conditions there will be approximately 3.1 times as much effluent pre- sent in Mud Creek than was required to kill 50% of the test organisms. The potential Tor chronic toxicity is indicated when the 7-day reproduction data is examined. The Chronic Value (ChV), in this case was 3.16%. The Chronic Value is a term commonly used in chronic toxicity test data analysis and lies within the interval bounded by the No Observed Effect Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC)1.1. The NOEC and LOEC in this test was 1.0% and 10% effluent respectively. During periods of low stream flow, data indicate there would be a significant adverse effect on neonate production. North Carolina water quality regulations state that any toxic substance or complex waste is considered acutely toxic at instream waste concentrations greater than one-third of the 96 hour LC50 values. The 48 hour effluent LC60 for Daphnia, pulex was 14%. Relating this to the water quality regulations' definition of acute toxicity, the threshold for acute toxicity is 4.6%. It is predicted that during 7010 conditions D. pulex will be acutely impacted. The IWC during periods of 7010 low stream flow (10.1%) exceeds, by a factor of two, the effluent concentration which represents an acutely toxic situation (4.6%). No acute response for D. pulex (or organisms of comparable sensitivity) is expected during average stream flow conditions as the IWC (2.4%) is less than the acute level (4.6%). Benthic macroinvertebrate sampling and analysis of Mud Creek upstream and downstream of this discharge indicate a community change in the creek below the discharge_ This change is attributed to a toxic impact based on lower taxa richness values and an increase in toxics tolerant taxa at the downstream samp- ling location. To summarize, relating existing information to an instream waste concentra- tion of 10.1% during 7Q10 stream flows (11% under the new permit), and 2.4% dur- ing average stream flows, the effluent will most likely impact sensitive species in Mud Creek during low flow conditions, and possibly during average stream flow_ i U.S_ EPA 1985. Short -Term Methods for Estimating the Chronic Toxicity of Efflu- ents and Receiving Waters to Freshwater Organisms. EPA/600/4-85/014. * See List of definitions in glossary for terms. 8 As specified in .0211(b)(L) of the NC NRCD, DEM Administrative Code Section: 15 NCAC 2B .0200. RECOMMENDATIONS 1.) The self -monitoring data from Hendersonville WWTP since October 1985 has indicated reduced acute toxicity with LC60's of greater than 90%. The facility has been switched to monthly chronic toxicity testing_ The NPDES permit should be modified upon reissuance or reopening to require the performance of chronic toxicity tests on a quarterly basis using protocols defined in the EPA Document 600/4-85/014 entitled "Short Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms". This testing should be performed as a seven day Ceriodaphnia survival and reproduction test. The effluent should be collected twice during the test period as 24 hour composite samples at the location described under acute testing. This test should consist of a minimum of five effluent concentrations plus a control series. One of the effluent concentrations should equal 10.1%, which represents the Instream Waste Concentration (IWC) during 7010 low flow of the receiving stream and the current daily permitted average discharge volume of the facility. The remaining concentrations should equal 5%, 10.2%, 20.4% and 90%. There may be no greater mortality than 20% in 90% effluent after 48 hours of.exposure. The resulting Chronic Value (ChV) of the seven day test should be greater than 10.1% defined as the geometric mean of the Lowest Observed Effect Con- centration (LOEC) and the No Observed Effect Concentration. The test will be considered passed if the Chronic Value is greater than 10.1% and acute mortality at 90% effluent is less than 20%. The failure of either parame- ters will be considered as failure of the test_ 2.) Sources of chlordane encountered in one effluent sample should be identified and closely monitored by the facility in order to insure instream concen- trations below the water quality standard of 0.004 ug/I for chlordane. 3.) Effluent concentrations of zinc and copper encountered in the two effluent samples did not exceed water quality action levels (zinc = 50 ug/I and cop- per = 15 ug/I) at either 7010 stream flow or at average stream flow. How- ever, sources of these two metals should be identified and monitored as they may be contributing to the whole effluent toxicity. 4.) Sources of the following compounds, although not present in the effluent at acutely toxic levels, should be identified and monitored in t-e•u of their classification as EPA Hazardous Wastes, EPA Priority Pollutants and EPA Priority Toxic Pollutants: a) Chloroform b) 1,1,1-trichloroethane c) Tetrachloroethene d) 1,1-dichloroethane e) trichloroethene APPEN.D 1 X 48 Hour Daphnia pulex Screening Bioassay Aquatic Toxicology Group N. C. Division of Environmental Management The Aquatic Toxicology Group performs 48 hour static bioassays using the c l adoceran Daphnia pulex to estimate the toxicity of waste discharge to aquatic life in receiving streams. All test and sampling glassware and equipment are washed with soap and hot water, then rinsed in nitric acid, acetone, and distilled/deionized water, to remove all toxins and contaminants. Effluent samples are collected by DEM Regional Office or Aquatic Toxicology personnel. All samples are collected chilled and above chlorination unless otherwise specified. Each sample is collected as a grab or 24 hour composite using an automatic sampler and is sent chilled to the Aquatic Toxicology Laboratory by state courier or bus. The sample must be received within 24 hours after collection. The samples are prepared for testing by being thouroughly mixed, adjusted to standard test temperature, and aerated if dissolved oxygen is below 40% saturation. Chlorine is removed with Sodium Thiosulfate if applicable. Initial pH and DO are also recorded. The effluent is then diluted with D. pulex culture waer, typically to seven concentrations (with replicates) from 0 to 90% effluent. Each test chamber receives 100 mis total volume and ten 24 hour old D. pulex test organisms. The test is conducted in a 20 degree centigrade incubator with a 14:10 hour I ight:dark cycle. Mortality of the D. pulex is recorded after 48 hours, along with final pH and dissolved oxygen. A 48 hour LC5 . or concentration of effluent lethal to 50% of the test organisms in 48 hours, is calculated from the mortality data. An instream waste concentration (IWO) for the effluent in the receiving stream is calculated using the treatment system design flow and low —flow (7Q10) stream flow. The LC50 and IWC are then used to predict instream toxicity. If the effluent toxicity and/or the IWC are high. a persistance bioassay may be conducted. This involves a second 48 hour static D. pulex bioassay on the same effluent sample after it has been exposed to light and aeration for an additional 48 hours. If there is a 100% reduction in the LC50, the effluent is considered to be non—persistant. 96 Hour On —site Flowthrough Bioassay Aquatic Toxicology Group N. C. Division of Environmental Management Candidacy for an on —site toxicity evaluation by the Aquatic Toxicology Group is determined on the basis of acute toxicity of the effluent in comparison with instream waste concentration. Acute toxicity is determined by a 48 hour screening static bioassay using Daphnia pulex. For each on —site, flowthrough bioassay, a pre —test site inspection is performed in order to: 1) Determine appropriate areas for phys i ca l placement of the mobile laboratory. 2) Acquire proper equipment and installation needed for electrical service. 3) Determine appropriate areas for effluent sampling and equipment needed for such. Sampling is done above chlorination unless otherwise specified. 4) Determine possible areas for dilution sampling (actual receiving waters or other unstressed. streams in the area) and equipment needed for such. 5) Collect additional samples of effluent and possible dilution waters for further static Daphnia pulex acute and static renewal Ceriodaphnia sp. reproduction bioassays to determine the range of concentrations of effluent for the flowthrough bioassay, to test for potential toxicity of possible dilution waters, and for fish acclimation to the chosen dilution water. 6) Determine route suitability to the facility for the mobile laboratory (eg. low clearances, poor road conditions). 7 Discuss test procedures and requirements with appropriate facility personnel. 8 Determine appropriate sampling sites and techniques for benthic macroinvertebrate surveys. Upon actual arrival on —site with the mobile laboratory, dilution water is obtained and dilution and effluent pumping systems are set up and tested. Two to three week old fathead minnows are wet transferred to the test chambers (containing approximately one liter of dilution water), ten fish to a chamber. Seven concentrations (withreplicates) including a control are used. The second day on -site the dilutor and the dilution and effluent pumping systems are turned on and the fathead minnow flowthrough bioassay is begun. A water bath is utilized to bring the effluent and dilution water to a constant 20 degrees centigrade. Test organisms are fed newly hatched brine shrimp twice daily throughout the test. A Ceriodaphnia static renewal reproduction bioassay using newborn organisms is begun the first day on —site. The organisms are transfered to fresh dilution and eff luent solutions daily and initial and final pH and dissolved oxygen are recorded. The number of young born per organism per day is recorded and mean cumulative reproduction is calculated for each concentration. The test is conducted in a 25 degree centigade incubator with 10 light:14 dark photoperiod. Test organisms are fed a mixture of yeast and algae. Individual chemical/physical parameter meters are calibrated daily according to DEM standards. Hydrolab systems measure and record dissolved oxygen, pH, temperature, and specific conductance in the test chambers with the highest and lowest concentration of effluent at 15 minute intervals throughout the test. These systems are calibrated at test initiation, the mid —point of the test, and test termination.Data from these systems is recovered daily and stored on magnetic tape and hard copy. On alternate days, samples of dilution water, effluent at the sampling site, final effluent, and the receiving stream upstream and downstream of the _27_ discharge point are analyzed for hardness. On variable effluents, daily residual chlorine measurements will be made at the above described sites. During the on —site evaluation, Biological Monitoring Group personnel collect benthos samples at the upstream, downstream and dilution sites (see Benth is • Macroinvertebrate Survey appendix). Where appropriate, electrofishing is undertaken upstream and downstream of the discharge to obtain resident fish population data. On a site —specific basis, various other efforts are undertaken, such as monitoring dissolved oxygen levels in the receiving stream. On a daily basis, test chamber screens are cleaned, dilution water is collected (where appropriate), effluent and dilution pumping systems are checked and adjusted as necessary, and pH, dissolved oxygen, and fish mortalities are recorded for each chamber. Two separate 24 hour composite samples of effluent are collected by means of an automatic sampler for chemical analysis. Receiving stream and dilution water samples are also taken for chemical testing. Static 48 hour Daphnia pulex bioassays are conducted on a 24 hour composite sample of the effluent and a grab sample of the influent. A photographic record is made of the treatment facility, sampling points, receiving stream, and sampling procedures while on —site. At the end of the 96 hour test period, the dilutor is turned off and final mortality observations are made. Breakdown and packing routines are performed and the mobile laboratory is transported back to the Cary Aquatic Toxicology Laboratory. Several special care operating procedures should be mentioned. At facilities that discharge for only a portion of the day, effluent samples are composited by the dilutor system into a large reservoir on board the mobile laboratory for use as the effluent while discharge is not in progress. If the effluent has a high oxygen demand, aeration systems for the test chambers are utilized and dissolved oxygen levels in the chambers are monitored closely in order to prevent levels from dropping below _40% saturation at test temperatures. In the event that actual receiving waters are deemed unfit for the test (i.e. potentially toxic), an alternate source of dilution water is sought in the vicinity. Ceriodaphnia s� Reproduction Bioassay Procedure Aquatic Toxicology Group N. C. Division of Environmental Management The Ceriodaphnia aquatic bioassay is conducted to estimate the effect of an effluent or other water sample on reproductivity. The cladoceran Ceriodaphnia sE. is used as test organism in e 7 day static renewal bioassay. A control and 8 concentrations of effluent ranging from 0.01% to 100% are typically used. There ere 10 animals per concentration, each animal in a one ounce polystyrene test chamber with 15 mis of solution. The test is conducted in a 25 degree centigrade incubator with a 14 light/ 10 dark photoperiod. The test is initiated with newborn animals, or neonates. Adults having brood sacs of 5 or more eggs with visible eyespots (indicating eggs are about to be released) are isolated and checked periodically. Neonates are removed and grouped according to time of birth. Selected groups are then composited to make the youngest set of 90 or more neonates born within a 4 hour period. The test is begun when the neonates are introduced into the test chambers. Temperatures must be within 2 degrees centigrade for transfer. The animals are transferred daily to new test chambers containing freshly mixed solutions. Chemical/physical parameters are measured twice for each batch of solutions. The initial xalue is taken before the animal is introduced and the final value after the animal has been transferred out the next day. Dissolved oxygen of greater than 40% saturation is necessary. The animals are fed daily, just after transfer. Each animal receives 1/2 standard dose of yeast and 1/2 standard dose algae (one drop or 0.05 mis of a — solution made by dissolving 0.25 grams active dry baker's yeast in 100 mis of distilled water plus one drop of a solution of 1.71 x 106 cells/ml Selenastrum capricornutum). As reproduction begins. only the adult is transferred to a new chamber. A drop of concentrated nitric acid is added to the old chamber. This kills the young so they can be easily counted under a dissecting microscope. A mean number of young produced per adult is calculated for each concentration. Mortality of greater than 10% in control test organisms invalidates a test. Benthic Macroinvertebrate Procedure Biological Monitoring Group N.C. Division of Environmental Management The sampling methodology requires that a stream or river be wadable. High water conditions may severely impair sampling efficiency by making critical habitats unaccessible. A fixed number of samples are collected for each station. These include: 2 kick net samples of riffle and snag areas; 3 sweep net samples of bank areas and macrophyte beds; 2 fine mesh washdown samples of rocks and logs; 1 elutriated sand sample; 1 leafpack sample; and 1 visual search of rocks, logs, leaves, and substrate. The benthic macroinvertebrates are picked out with tweezers and preserved in alcohol. A collection card is filled out which includes such data as canopy cover, dissolved oxygen, pH, stream temperature, substrate composition and stream morphology at the site. Organisms are identified to the lowest possible taxonomic level, generallyto species. Density of each taxon is rated as Rare (1 or 2 individuals), Common (3 to 9), Abundant (10 or more). Most organisms may be identified using only a dissecting microscope, but Oligochaeta and Chironomidae must be mounted and identified with a compound microscope. Reference collections are maintained and all samples are kept and stored by study area. The first level of analysis -summarizes the data by total number of taxa or "taxa richness" (S) and density (N) for each station.The association of good water quality with high taxa richness is intuitively obvious even to the non -biologist. Increasing levels ofpollution gradually eliminate the more sensitive taxa, leading to lower and lower taxa richness. Clean, unstressed, aquatic communities are characterized by a density (N) and taxa richness (S) above average levels. Toxic stress (including pesticides and metals) reduces both S and N below the average. Sediment stress, especially at low levels, tends to decrease density, but affects taxa richness only slightly. Finally, nutrient enrichment tends to increase the total number of organisms, while selectivelyfavoring a few types of organisms tolerant to this type of pollution. The second level of analysis summarizes data by taxonomic groups (mostly orders of insects). A particularly useful parameter is the "EPT" value: the sum of the taxa richness for the intolerant insect groups Ephemoroptera, Plectoptera, and Trichoptera. The EPT value is consistantly related to water quality. The final step in data analysis is to summarize the data separately for each taxa.The presence or absence of individuals of "indicator species" is, in itself, insufficient for characterizing water quality. Tolerant species are present in all aquatic habitats, however these species will usually become dominant only in polluted systems. Information on pollution tolerance of any given taxon, combined with quantitative data on -30- its distribution can often be related to specific chemical or physical changes in the environment. List of Definitions Aquatic Toxicology Group N.C. Division of Environmental Management Acclimation - refers to the process of gradually adjusting organisms from voter of one type to another so that the organisms ere not stressed from radical changes in temperature, hardness, pH, ionic strength, etc. Acute toxicity - the effect a short term exposure to a chemical or substance has on en organism; usually defined es death of that organism. Application factor - e value which estimates en i nstream toxicant level that will be safe et a chronic level for resident organisms from acute toxicity data, usually defined by a fraction of the LC50. Aquatic - having to do with voter. Aquatic Toxicology Group - the group vithi n the Biological Services Unit (Water Quality Section) which performs aquatic bioassays for the Division of Environmental Management. The Group is located et the Cary laboratory facilities. All test organisms (including Daohniu Wm, Periodeohnia IL, and fathead minnows) are cultured et these facilities by Aquatic Toxicology personnel. Benthos/Benthic mecroi nvertebretes - e vide assemblage of invertebrate animals (insects, crustaceans, molluscs, etc.) which live in streams, are en important food source for fish populations, and are used as long term water quality indicators. Bioassay - e test used to determine the effects of a chemical or substance on an organism. Cadmium - one of the toxicants recommended by EPA for quality assurance testing of the health of aquatic organisms. Calibration - the adjustment of meters or systems with standards of known values in order to assure the quality of data obtained from these meters or systems. Ceriodeohnie `p - e smell cledoceran crustacean. It is found throughout most of North America and obtains e maximum sire of approxi motel y 1 mm. This organism has been adopted for aquatic bioassay testing because of its small size, ease of culture under laboratory conditions, stability of genetic strains, and sensitivity to toxic substances. It is generally used in e 7 day static renewal "mini -chronic" bioassay testing for mortality, time to sexual maturity end reproductive rate. Ceriodaohnie ape is accepted in the field of equetic toxicology for testing in moderately soft voters. Chronic toxicity - the effect of a chemical or substance on en organism, usually during a longer period of time then that measured for acute toxicity. This effect is usually measured as a non -fatal response (eg. reduction in growth, egg production, predator avoidance, feeding rate, etc.). Test for chronic toxicity ere frequently performed during the entire life cycle of the organism. Chronic vel ue(ChY): A numeric value representi ng the geometric mean of the numeric values of concentrations analyzed as the No Oberserved Effect Concentration (NA.E.C.) and the lowest Oberserved Effect Concentration (L.O ECC.) by chroic toxicity testing. The chronic value is en sstimete of the toxicant concentration that will be the actual no effect concentration based on the —32— chronic effect tested. ChY-Antiiog((Log 10LA.EcC.+ Lag 10NA.E.C.) /2) Composite - e sample or method of sampling used to obtain data on a substance which may vary overtime or apes. For example, a time or temporal composite of a stream vouid be one collected et intervals of time et the SOME location. This is frequently accomplished with automatic sampling devices. Dia& Qyba (water flee) - a smell cledoceran crustacean. It is found throughout most of North America and obtains a maximum size of approxi metel y 3.5 mm. This organism has been adopted for aquatic bioassay testing because of its smell size, ease of culture under laboratory conditions, stability of genetic strains, and sensitivity to toxic substances. it is generally used in e 48 hour static bioassay testing for mortality. D pulex is widely accepted in the field of aquatic toxicology for testing in moderately soft eaters. Design flow - the volume of water end waste that is initially planned to pass through a facility or waste treatment plant and still allow maximum operating efficiency. Design floe is usually expressed in millions of gallons per day (mgd). Dilution (water) - the water used in bioassay tests to dilute the waste water to various concentrations (expressed es percent). Wherever possible, this water is from the actual stream that receives the west, upstream from that waste. When this is not possible, other suitable water is obtained. Dilutor - refers to a modified Mount and Brungs design serial dilution apparatus which receives'dil ution water and effluent/caste and, through a series of chambers and electrical solenoid valves, mixes the effluent and dilution into a series of concentrations for the test (expressed es percentages of 100% effluent). Electrofishing - method for collecting fish using electrical shock to momentarily stun the fish so they float to the surface and are easily netted. Effluent - the waste water exiting a facility which is discharged es treated waste to a stream or es untreated waste to some other facility. fathead minnow (Pimeohelas promelas) - e small fish which occurs throughout much of North America. It obtains a maximum size of approximately 100 mm and is raised commercially es bait fish. The fathead minnow has been raised for numerous generations in a number of laboratory culture for use in toxicity testing. The fish can produce eggs year round in the laboratory environment under correct conditions which produce test organisms es needed. Flow -through - the flow -through bioassay utilizes which either continuously of occasionally replace effluent/toxicant concentrations throughout the test in an attempt to Simulate stream conditions where new effluent end dilution eater are continually flowing through en organism's habitat. Hydroleb* - a multiparemeter instrument which measures and records temperature, pH, dissolved oxygen, and specific conductance of water. "Use of this term or system does not constitute an endorsement I nstreem waste concentration (IWC) - the percent concentration of an effi uent/toxicant which is present in a stream under assumed worstcese conditions. The IWC is derived from the formula: (Df / —33— (7010 + DF) ] x 100 = IWC (%), where OF is the design flow (in cfs) of the facility in question and 7Q 10 is the 10 year, 7 day, low floe (in cfs) of the receiving stream. LC50 - that concentration or percentage of a waste/chemical/substance which is lethal to 50% of test organisms over a stated period of time Lowest Observed Effect Concentretion(L O.ECC.)- The lowest concentration of toxicant to which organisms are exposed in a life -cycle or partial life -cycle test, which causes a statistically significantly adverse effect on the observed parameters(usuall y hatchability, survival, growth, and/or reproduction). NPDES - National Pollutant Discharge Elimination System. A system devised by the Federal Government and adopted by North Caroline for the permitting, monitoring, and pollution abatement of dischargers to surface eaters. Neonate - roughly translated to newly born. In reference to panhme pulex, the neonate refers to the life stage in the first end early second meter, generally the first 24 hours of its life. No Observed Effect Com entration(N.O.ECC.)- The highest concentration of toxicant to vhlch organisms are exposed in a life -cycle or partial life -cycle test, which causes no statistically significant adverse effect on the observed peremeters(usually hatchability, survival, growth, end/or reproduction.) Screening bioassay - e testing system established to determine general levels of acute toxicity of compounds/discharges using 48 hour Qaohnie.Pulex tests. 7010- the measurement of a stream's lowest average daily floe over e 7 day period during a 10 year span, generally stated es flow in cubic feet per second (cfs). Sodium pentechlorophenete - e chemical accepted by EPA as a toxicant for quality assurance testing of the health of aquatic organisms. This chemical is an organic pesticide. Static refers to en aquatic bioassay in which toxicant/effluent concentrations ere set up et the beginning of the test and not changed for the rest of the test. This test is generally short term es compered to e flow -through or replacement test beceuse of potential degradation of the toxicant/effluent. Taxe - refers to a group of genetically related organisms, (i. e. genus, order, species). Taxa richness - number of taxa. 30Q2 - the measurement of a stream's lowest average dell y flow over a 30 day period during e 2 year span, generally stated as flow in cubic feet per second (cfs). Toxicity - the edveree effect of a chemical/substance on en organism. Toxicity is usually defined es a fatal or non -fatal response over a give period of time. UT - Unnamed tributary - e term given to streams which have no accepted name.