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COLORADO DEPARTMENT OF HEALTH. Water Quality Control Division
<br />Rationale -Page 8, Permit No. CO-0043648
<br />B. Receiving Water Data
<br />1, uali -Quality data for Arequa Gulch are available jot stations that have been operated by the Cripple
<br />Creek & Victor Mining Company.
<br />Station AG-1.0 was originally located at the sprang that /ms been covered by the Arequa Gulch Rock
<br />Storage Area, which is upstream of Ute Valley Leach Facility. Since the time when tl:e springs were routed
<br />t/trougit tl:e VLF underdrain, w/tich was 6egttn in July, 1994, and carnpleted in October, /994, data has
<br />been collected at the outfall front [!te 4"pipe tlta! carries the flow under rite VLF.
<br />Station AG-].5 ltas always been located in !)te area that lies below the lowest extent of VLF, and is still in
<br />operation.
<br />For both of these stations, it is possible that construction of the project features itas affected flows or water
<br />gttaliry. As a result, data summaries for the stations have been performed ttsiag nvo different periods of
<br />record. While there are a variety of activities that have occurred which could be used to distinguish pre-
<br />project quality from post project quality, the most important consideration for the purposes of this permit is
<br />to ntaintaln consistency with rite period-of-record that was presented to the Water Quality Control
<br />Commission in the setting of temporary standards.
<br />For point AG-1.0, the period-of-record that was used in the setting of the standards was June, 1987,
<br />through February, 1995. For point AG-1.5, the period used was July, 1990, through April, 1995. The
<br />following summaries are based upon the same periods, with data collected after the ertd of tl:e llvo period
<br />for each poin! being summarized separale[y.
<br />It should 6e noted that in the latest data submittal from the mining company, additional, earlier data
<br />extended back to 1985 was included. Tltis data l:as just recently been located by the company, and was not
<br />utilized in the setting of temporary modification standards.
<br />For Squaw Gulch, no water quality data is available.
<br />Table II/ - 3 -- Quality of Receiving Water
<br />Station AG-1.0, Above the Valley Leach Facility, Jitne, 1987-February, 1995
<br />No: .
<br />Pararrteter . Sarrip(es Min. Max. 'Avg. Std.Dev. Median .85th Pcntl
<br />Discharge, gpm 26 0.0 992 58
<br />Temp, °F 26 32.7 71.8 52.3
<br />pH, su 28 3.5 6.6 0.77 5.1 4.3
<br />Dissolved Oxygen, mg/1 11 4.2 9.1 7.0
<br />Total Suspended Solids, mg/l 23 0.0 220 28.0
<br />Total Hardness, mg/1 as CaCO~ 18 280 580 389
<br />Nitra[e, mgt! as N 27 0 1.0 0.24 0.29 0.14 0.49
<br />Total Cyanide, mg/[ 29 0.00 0.086 0.0 0.0
<br />WAD Cyanide, mg/l 28 0.00 0.008 0.00 0.00
<br />Free Cyanide, mg/l 29 0.00 0.00 0.0 0.0
<br />Aluminum, Dissolved, mg/l 26 3.00 32.0 14.4 8.0 15 22
<br />Arsenic, PD, mg/l 21 0.00 29.0 0.0 0.0
<br />Cadmium, Dissolved, mg/l 27 0.00 0.039 0.01 0.010 0.009 0.017
<br />Chromium, PD, moll 20 0.00 0.007 0.0 0.05
<br />WAD -Weak Acid Dissociable
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