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COLORADO
<br />Water Quality Assessment
<br />�. p ;!• Department of public
<br />X87`I Health b Environment
<br />Because the low flow (Qi) for No -Name Gulch, East Pyeatt Gulch, Middle Flume Gulch, East Middle Flume
<br />Gulch, East Flume Gulch, Oak Gulch and Deacon Gulch is zero, the WQBELs for the pollutants of concern are
<br />equal to the in -stream water quality standards.
<br />Because the Yampa River is designated as TELE species habitat, the WQBELs for the Yampa River for pollutants
<br />of concern with aquatic life standards are equal to the instream water quality standard (no dilution). For
<br />health based pollutants (TR As, Cr3, Dissolved Fe, Dissolved Mn, Hg, and Sulfate), the upstream background
<br />pollutant concentrations used in the mass -balance equation will vary based on the regulatory definition of
<br />existing ambient water quality. For most pollutants, existing quality is determined to be the 851h percentile.
<br />For metals in the total or total recoverable form, existing quality is determined to be the 50th percentile.
<br />Calculation of WQBELs
<br />Using the mass -balance equation provided in the beginning of Section VI, the acute and chronic low flows set
<br />out in Section IV (for parameters eligible for dilution in the Yampa River), ambient water quality as discussed
<br />in Section IV, and the in -stream standards shown in Section III, the WQBELs were calculated. The data used
<br />and the resulting WQBELs, M2, are set forth in Table A -7a and A -7b for the chronic WQBELs and A -7c for acute
<br />WQBELs. There are no acute standards for pollutants of concern on segment COLCLY03a.
<br />Temperature: The 7E3 low flow is 0 in all twelve months, and the discharge is to an effluent dependent
<br />(ephemeral stream without the presence of wastewater); therefore, in accordance with Regulation
<br />31.14(14), no temperature limitations are required.
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<br />4300 Cherry Creek Drive S., Denver, CO 80246-1530 303-692-2000 www.cotorado.gov/cdphe/wqcd I ��
<br />Table A -8a
<br />Chronic WQBELs for COLCLY03a - Deacon Gulch Outfall 025
<br />Parameter
<br />Q, (cfs)
<br />Q2 (cfs)
<br />Q3 (cfs)
<br />M1
<br />Ms
<br />Mr
<br />As, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0
<br />100
<br />100
<br />Be, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0
<br />100
<br />100
<br />Cd, TR (pg/1)
<br />0
<br />3.3
<br />3.3
<br />0
<br />10
<br />10
<br />Cr+3, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0
<br />100
<br />100
<br />Cu, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0
<br />200
<br />200
<br />Pb, TR (pg/1)
<br />0
<br />3.3
<br />3.3
<br />0
<br />100
<br />100
<br />Mn, TR (pg/1)
<br />0
<br />3.3
<br />3.3
<br />0
<br />200
<br />200
<br />Mo, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0
<br />160
<br />160
<br />Ni, TR (pg/1)
<br />0
<br />3.3
<br />3.3
<br />0
<br />200
<br />200
<br />Se, TR (pg/1)
<br />0
<br />3.3
<br />3.3
<br />0
<br />20
<br />20
<br />Zn, TR (pg/l)
<br />0
<br />3.3
<br />3.3
<br />0 2000
<br />2000
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<br />4300 Cherry Creek Drive S., Denver, CO 80246-1530 303-692-2000 www.cotorado.gov/cdphe/wqcd I ��
<br />Table A -8b
<br />Chronic WQBELs for
<br />COLCLY03b - No -Name Gulch, East Pyeatt Gulch, Oak Gulch, Middle Flume
<br />Gulch, East Middle Flume Gulch and East Flume Gulch
<br />Outfalls 002, 011, 017, 020, 021 and 023
<br />Parameter
<br />Q, (cfs)
<br />Q2 (ds)*
<br />Q3 (cfs)*
<br />M1
<br />Ms
<br />M2
<br />As, TR (pg/1)
<br />0
<br />Variable
<br />Variable
<br />0
<br />100
<br />100
<br />Be, TR (pg/1)
<br />0
<br />Variable
<br />Variable
<br />0
<br />100
<br />100
<br />Cd, TR (pg/1)
<br />0
<br />Variable
<br />Variable
<br />0
<br />10
<br />10
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