2021-05-18_HYDROLOGY - C1981019

• Permit No: C1981019
• IBM Index Class Name: Hydrology
• Doc Date: 5/18/2021
• Doc Name: Correspondence
• From: Tri-State Generation and Transmission Association, Inc.
• To: DRMS
• Email Name: ZTT
• Email Name: JDM
• Media Type: D
• Archive: No

DocuSign Envelope ID: D07924E6-3D94-4398-A066-B683COBAB33E
4.2 Ceriodaphnia dubia Chronic Toxicity Test
TEST: 7-day chronic with Ceriodaphnia dubia OPERATORS: LAG, JW, TE, CL, AW
Start: 11/5/20 13:40
End: 11/12/20 13:30
Test Substance: 1.0 g ethanol/g SO4-treated Effluent
Client/Project: Elk Ridge Mining and Reclamation, LLC
Table 10: Summary results of C. dubia chronic toxicity test.
Treatment 0 20 40 60 80 100
%Treated Effluent
#alive/#exposed 10/10 9/10 8/10 8/10 6/10 6/10
%survival 100 90 80 80 60 60
Normalized repro/#females 39.1 36.6 31.2 14.8 6.2 0.2
exposed ±SD ±7.4 ± 13.6 ± 10.6 ±9.6 ±6.5 ±0.4
Dissolved 02 range 6_6 6_6 6_1 6_1 6_3 6_1
(mg/L) 5.9 5.7 5.7 5.6 5.4 5.8
pH range(SU) 8_2 8_7 8_8 8_7 8_7 8_7
8.1 8.5 8.7 8.6 8.6 8.6
Conductivity range 395 1266 2040 2887 3490 4340
(pmho/cm) 350 1064 1779 2437 2996 3750
Temperature range(°C) 24.6 24.7 24.8 25.0 25.0 25.2
22.0 23.1 22.4 22.8 22.1 22.5
Statistical Analysis:
Survival:
NOEC (Fisher Exact/Bonferroni-Holm) = 100% 1.0 g ethanol/g SO4-treated Effluent
IC25(ICp Method) = 65.0% 1.0 g ethanol/g SO4-treated Effluent (95% C.I. 30.0 to
100.0)
Normalized Reproduction:
NOEC (Steel Many-One Rank Sum) = 40% 1.0 g ethanol/g SO4-treated Effluent
IC25(ICp Method) = 42.3% 1.0 g ethanol/g SO4-treated Effluent (95% C.I. 19.5 to
47.9)
GEI Consultants,Inc. 12 February 2021
Ecological Division Whole Effluent Toxicity Test Report
Stantec-Elk Ridge Mining and Reclamation,LLC