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Cotter Corporation Water Quality Assessmeut
<br />CO-0036251
<br />-Table A-6
<br />Ambient Water Quali for the Dolores River
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<br />Tem °C 11 1.2 4.7 21 8.9 30 1
<br />DO m 36 8.1 9.6 13 10 5 2
<br />H su l i 8.2 8.3 8.4 8.3 6.5-9 1
<br />Hardness (mg/1 CaC03)
<br />10
<br />145
<br />211
<br />265
<br />223
<br />NA
<br />1
<br />Cd, Dis u 1) 31 0 0 0 0.32 2.1 2,3
<br />Cu, Dis u 1) 29 0 8 15 7.7 23 2,3
<br />Fe,Trec u ) 15 226 590 3350 1449 1000 2
<br />Pb, Dis u I) 29 0 0 0 0 12 2,3
<br />Mn, Dis (u 1 36 0 23 71 34 1000 2,3
<br />H, Dis u 15 0 0 0 0 NA 2,3
<br />Se, Dis u 1 7 0 I.0 3.6 2.4 5 2,3
<br />A , Dis u 1) 19 0 0 0.2 0.042 1.3 2,3
<br />Zn, Dis u /1 3b 0 0 0 1.4 209 2,3
<br />hl 11 8 120 17 6
<br />Sulfate m 1 10 53 120 196 145 NA 1
<br />TSS m 1 36 13 70 405 758 NA 2,3
<br />Radium 226 and 228
<br />( Ci/1
<br />30
<br />0.39
<br />0.90
<br />1.4
<br />1.1
<br />5
<br />4
<br />Note 1: Data taken from USGS water quality station 09169500 (Dolores River at Bedrock), located approximately 3 miles upstream from the
<br />confluence of the Dolores River with East Paradox Creek.
<br />Note 2: 1n the absence of current data for this pammetey historical data from WQCD gage station 85 (Dolores River above confluence with San
<br />Migue]), located approzitnately 3.5 miles downstream from the Dolores River and East Paradox Creek confluence were used. 'These data reflect a
<br />period of record from January 1990 through September 1994.
<br />Note 3: When sample results were below detection levels, the value of zero was used in accordance with the CO WQCD's standard approach for
<br />summarization and avem 'ng purposes.
<br />Note 4: Tn the absence of current data for this parameter, historical data from WQCD gage station 85 (Dolores River above confluence with San
<br />Migue(), located approximately 3.5 miles downstream from the Dolores River and East Paradox Creek confluence were used. These data reflect a
<br />period of record from Au st 1970 throu h November 1983.
<br />III. Water Quantity
<br />The Colorado Regulations specify the use of low flow conditions when establishing water quality
<br />based effluent limitations, specifically the acute and chronic low flows. The acute low flow, referred
<br />to as 1E3, represents the one-day low flow recurring in athree-year interval. The chronic low flow,
<br />30E3, represents the 30-day average low flow recurring in a three-year interval.
<br />Low Flow Analysis
<br />According to the Water Commissioner, Bull Canyon is fed by hundreds of small springs that seep
<br />and flow, but often dry up after traveling a short distance. East Paradox Creek, however, is a dry
<br />draw, fed only by rainstofms. Likewise, the tributaries to Bull Canyon and bast Pazadox Creek are
<br />Appendix A Page 8 of 13 Final
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