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Mr. Steve S. Shuey <br />March 31, 1992 <br />Page 2 <br />Monitoring of the fan level precipitation gauge was initiated in 1978 and <br />continued through 1987. Precipitation monitoring was conducted at the <br />Steven's C~rlch wellfield in conjunction with evaporation pan monitoring during <br />1989, but was omitted during 1988, 1990, aril 1991. <br />Flv~u monitoring at station SW-5 was initiated in 1982 and continues to date. <br />Monthly flow measurements at this station provide only partial quantification <br />of total annual runoff volumes from the basin. Typically, flow measurements <br />at station SW-5 are collected only during months when irrigation water is <br />flowing in the area. <br />Limited snow course monitoring data is available for 1983 - 1985. Grourxiwater <br />level observations from wells SG-B and SGT were apparently discontinued <br />following 1986 (measurements from these wells were used to calculate <br />groundwater storage changes in the initial water balance). Groundwater level <br />observations for wells SM-2 and SM-9 have been collected periodically since <br />1986. Meter readings for water volumes pumped from the Steven's GUlc]i <br />wellfield continue to be collected on an approximately monthly basis. <br />Permit No. C-81-038, Volume 4, Hydrology Appendices, contains an estimated <br />water balance for the Steven's Gulch watershed for that portion of the <br />watershed located above the wellfield. The water balance presented provides a <br />generalized description of the methodology aril data utilized and infers that <br />further monitoring will be required to verify or modify the resultant <br />estimates. In the estimated water balance, surface runoff totaling 10.3 <br />inches is attributed to the upper portion of the Steven's Gtilch drainage. <br />This figure is apparently developed by utilizing runoff measurements from <br />surface water monitoring station SW-5 and reducing them by a factor of 0.64 to <br />correspond with the reduced drainage area as measured at the wellfield. Given <br />10.3 inches of runoff, a total annual runoff volume of approximately 1390 <br />acre-feet results for the upper watershed area (1619.2 acres). This infers <br />approximately 2170 acre-feet of runoff volume measured at station SW-5 <br />(1390/0.64 = 2170). A review of SW-5 data (refer to 1990 Annual Hydrology <br />Report, Volume 1, Table 16) shows that in 1983, ten months of flow measurement <br />totaling 385.4 acre-feet were docimiented. No additional information regarding <br />SW-5 flows in 1983 is available in mine records. <br />A copy of Map No. 2-7 included with this submittal delineates the Steven's <br />Gulch watershed and mining development within the area. With the exception <br />of the northernmost development of Panel B, virtually all of the mining <br />proposed within the upper Steven's Gulch watershed is cortq~lete as of this <br />date. The remainder of Panel B and potentially Panel C have yet to be <br />developed within the lower portion of the Steven's Gulch watershed. The <br />scheduled mining of these panels will be completed before sufficient data to <br />define a water budget is compiled. <br />Stipulation No. 5 remains in effect and was carried forward in the 1988 <br />Findings docimient dated July 21, 1988 as Stipulation No. 30 (refer to <br />page 15). COVCC aclmowledges it's oversight in failing to conduct <br />precipitation and evaporation monitoring during 1990 and 1991, but questions <br />the utility of reestablishing the monitoring efforts at this point. <br />Hydrologic data and observations collected to date suggest a high degree of <br />