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CM0001910 <br />1.0 INTRODUCTION <br />A limnological monitoring program was initiated in the newly constructed Eagle Park Reservoir in <br />August 1998, and was continued in 1999 and 2000. Limnological samples were collected on one <br />occasion in August of each year This three-year investigation was conducted for Climax Molybdenum <br />Company (formerly Cyprus Climax Metals Company). The objectives of this monitoring program were <br />to collect baseline limnological data to be used to document conditions in the new reservoir and changes <br />in water quality in the initial years of operation. Results of the 1999 and 2000 sampling efforts are <br />presented herein with comparisons to the 1998 results as appropriate. Results of monitoring in 1998 are <br />presented in a separate report (Aquatics Associates 1999). <br />Eagle Park Reservoir is situated in the headwaters of the East Fork Eagle River drainage at an elevation of <br />approximately 10,700 feet above mean sea level (m.s.l.). The location of the study area is topographically <br />depicted in Figure 1 Eagle Park Reservoir is a new impoundment, created by cleaning out the area <br />formerly known as the No. 4 Dam Reservoir For many years, the No. 4 Dam Reservoir acted as a <br />sediment basin for oxide tailings that resulted from the isolation of some kinds of molybdenum ore, which <br />were processed at the Climax Mine facility (Home 1998). By the winter of 1996, tailings and sediment <br />were removed from the pond area during restoration and rehabilitation activities. Almost all of the <br />contaminated sediment was removed by excavation down to the original soil level. In the late winter and <br />spring 1997, water was diverted from the Chalk Mountain Interceptor and the Upper and Lower North <br />Interceptors into Eagle Park Reservoir, which began filling for the first time. The interceptors bypass <br />natural and surface runoff flows and tributary streams around the Climax plant process contact waters; <br />consequently, the reservoir was filled and is maintained with water that is not from molybdenum <br />extraction. The reservoir was about half filled by June 1997, and was almost full by the time of sampling <br />in the summer 1998. The reservoir was near maximum capacity in both 1999 and 2000. <br />Eagle Park Reservoir is approximately 62 surface acres with a storage capacity of approximately 3,000 <br />acre-feet when full. The reservoir is primarily used as a water storage facility supplying water for <br />artificial snowmaking activities at local ski areas, municipal uses, and augmenting downstream water <br />withdrawals for maintenance of instream flows. The operational strategy for the reservoir involves water <br />withdrawals in the fall, primarily in October and November, and occasionally during other times of the <br />year to meet water demands. Withdrawal of 1,500 acre-feet of water is possible through the outlet <br />structure located in the north comer of the reservoir at a depth of about 50 feet. Additional water can also <br />•