2018-03-01_HYDROLOGY - C1981010 (2)

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COLORADO Department of Public Health b Environment Water Quality Assessment Total Maximum Daily Loads and Regulation 93 - Colorado's Section 303(d) List of Impaired Waters and Monitoring and Evaluation List Stream segments COLCLY03a, COLCLY03b and COLCLY02 are not listed on the Division's 303(d) list of water quality impacted streams and are not on the monitoring and evaluation list. IV. Receiving Stream Information Low Flow Analysis The Colorado Regulations specify the use of low flow conditions when establishing water quality based effluent limitations, specifically the acute and chronic low flows. The acute low flow, referred to as 1E3, represents the one -day low flow recurring in a three-year interval, and is used in developing limitations based on an acute standard. The 7 -day average low flow, 7E3, represents the seven-day average low flow recurring in a 3 year interval, and is used in developing limitations based on a Maximum Weekly Average Temperature standard (MWAT). The chronic low flow, 30E3, represents the 30 -day average low flow recurring in a three- year interval, and is used in developing limitations based on a chronic standard. Based on information provided by the facility and the local water commissioner, the immediate receiving streams for Trapper Mine have a low flow of zero. Chronic 11 pgA e(0.8545(ln(hardness))-1.7428) Lead, Dissolved Acute 82 pg/l [1.46203-0.14571 21n (hardness)] [e(1.273((n(hardness))-1.46)] Chronic 3.2 pg/t [1.46203-0.1457121n(hardness)][e0.273((n(hardness))-4.705)] Manganese, Dissolved Acute 3207 pg/t e(0.3331(ln(hardness))+6.4676) Chronic 1772 pg/t e(0.3331(In(hardness))+5.8743) Nickel, Dissolved Acute 562 pg/1 e(0.846(ln(hardness))+2.253) Chronic 62 pg/t e(0.846(ln(hardness))+0.0554) Selenium, Dissolved Acute 18.4 pg/l Numeric standards provided, formula not applicable Chronic 4.6 pg/l Numeric standards provided, formula not applicable Silver, Dissolved Acute 2.9 pg/l V2 e(1.72(In(hardness))-6.52) Chronic 0.46 pg/l e0.72(In (hardness)) -9.06) Zinc, Dissolved Acute 195 pg/1 0. 978e(0.9094(ln(hardness))+0.9095) Chronic 147 pg/l 0.986 e(0.9094(In(hardness))+0.6235) Total Maximum Daily Loads and Regulation 93 - Colorado's Section 303(d) List of Impaired Waters and Monitoring and Evaluation List Stream segments COLCLY03a, COLCLY03b and COLCLY02 are not listed on the Division's 303(d) list of water quality impacted streams and are not on the monitoring and evaluation list. IV. Receiving Stream Information Low Flow Analysis The Colorado Regulations specify the use of low flow conditions when establishing water quality based effluent limitations, specifically the acute and chronic low flows. The acute low flow, referred to as 1E3, represents the one -day low flow recurring in a three-year interval, and is used in developing limitations based on an acute standard. The 7 -day average low flow, 7E3, represents the seven-day average low flow recurring in a 3 year interval, and is used in developing limitations based on a Maximum Weekly Average Temperature standard (MWAT). The chronic low flow, 30E3, represents the 30 -day average low flow recurring in a three- year interval, and is used in developing limitations based on a chronic standard. Based on information provided by the facility and the local water commissioner, the immediate receiving streams for Trapper Mine have a low flow of zero. Pae 16 of 40 4300 Cherry Creek Drive S., Denver, CO 80246-1530 303-692-2000 www.colorado.gov/cdphe/wqcd Ad 7, Table A -6a Low Flows for No -Name Gulch, East Pyeatt Gulch, Middle Flume Gulch, East Middle Flume Gulch, East Flume Gulch, Oak Gulch and Deacon Gulch at the Trapper Mine Low Flow Annual Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec (cfs) 1E3 Acute 0 0 0 0 0 0 0 0 0 0 0 0 0 Pae 16 of 40 4300 Cherry Creek Drive S., Denver, CO 80246-1530 303-692-2000 www.colorado.gov/cdphe/wqcd Ad 7,