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Schwartzwalder Mine -Hydrologic Evaluation of Mine Closure and Reclamation 48 <br />6.2 Previous Studies of Surface Water Quality <br />The USGS and others have performed several studies of water quality in Ralston Creek. Most of these <br />studies were associated with the Schwartzwalder Mine discharge permit. <br />Yang'Z and Edwards13 (1984) collected water samples and bed sediment samples from Ralston Creek and <br />Reservoir during the winter of 1980 and spring of 1981 for uranium and radium analyses. They determined <br />that the concentrations of uranium and radium in Ralston Creek, 400 feet upgradient of the Schwartzwalder <br />mine, were 4.0 mg/L and 0.13 pCi/L, respectively. <br />R.G. Otto & Associates (1984) performed a detailed survey of surface and groundwater quality to assess <br />the impact of runoff and seepage from the waste rock piles on the water quality in Ralston Creek. Surface <br />water samples were collected upstream and downstream of the waste rock piles and groundwater samples <br />were collected downslope of the disposal site from September 1983 through August 1984. The study <br />concluded that the waste rock piles had no measurable impact on water quality in the stream, with the <br />possible exception of stream uranium levels. The uranium data were inconclusive for determining impact, <br />and the uranium levels in Ralston Creek downstream of the waste rock piles were well below the Colorado <br />Basic Stream Standards. <br />6.3 Surface Water Sample Stations <br />6.3.1 Compliance Monitoring Stations <br />Monthly reporting of water quality in the treatment plant discharge water is required under Cotter's NPDES <br />discharge permit. In addition, water quality has been monitored monthly (1990 to 2006) and quarterly <br />(January 2007 to present) at the designated point of compliance in Ralston Creek (Station SW-BPL) and <br />the results are submitted in an annual report to the Division of Reclamation, Mining and Geology (DRMG). <br />6.3.2 Additional Non-Routine Sampling <br />In addition to the compliance monitoring point in Ralston Creek (SW-BPL), five other stations have been <br />monitored monthly from 1990 to 2002 and periodically (monthly to semi-annually) from June 2002 to <br />September 2007. These stations are currently on a quarterly sampling schedule. The purpose of these <br />samples was to understand upstream sources, further characterize the creek, and, at station SW-ARH, to <br />evaluate the potential effects of an ore truck spill on the creek. <br />Two of the stations are located above the point of compliance. The uppermost station is located in Ralston <br />Creek above the waste rock dumps (SW-AWD). The second is located above the former water treatment <br />plant discharge location (SW-A001). Three of the stations are located downstream of the point of <br />compliance: SW-ARH, SW-FBRG, and SW-LLHG, which is located on Ralston Creek at the Long Lake <br />Head Gate, approximately 1.5 miles downstream from the Schwartzwalder Mine. <br />The period of record extends from approximately 1973 to the present14. The data set contains dissolved and <br />total uranium and radium, as well as field parameters (temperature, pH, conductivity, and dissolved <br />oxygen.) A longer suite of parameters is analyzed approximately annually at these stations, as discussed <br />Section 6.5. <br />iz Affiliated with the USGS at the time. <br />13 Affiliated with the Colorado School of mines at the time <br />14 The surface water quality data evaluated for this report ranges from 1998 (or 1990 for uranium) to September 2007. <br />Whetstone Associates • <br />4109B.071116 <br />