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Environmental Protection Plan, Schwartzwalder Mine 8-5 <br />• <br />60.0 <br />50.0 <br />40.0 <br />M0 Avg Minimum Flow <br />® Monthly AverageFlow <br />r --- IAvg Maximum Flow <br />tAvg Precipitation <br />5.00 <br />N <br />w <br />V <br />30.0 <br />0 <br />LL <br />N <br />d <br />3.00 <br />c <br />is <br />• <br />20.0 <br />10.0 <br />0.0 <br />Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec <br />4.50 <br />4.00 <br />3.50 <br />C <br />2.50 2 <br />io <br />EL <br />2.00 v <br />d <br />a <br />1.50 <br />1.00 <br />0.50 <br />0.00 <br />Figure 8-1. Average Flow Rates in Ralston Creek vs. Monthly Mean Precipitation <br />(i).2 Ralston Reservoir <br />Ralston Reservoir is part of Denver Water Board's Moffat Tunnel Collection System, one of three major <br />water collection systems that include diversion, collection and transmission facilities that store and <br />distribute raw water prior to treatment. The Moffat Tunnel Collection System captures water from the <br />Williams Fork River, the Fraser River, South Boulder Creek and Ralston Creek, and subsequently delivers <br />this water for use in the Denver area (Figure 8-2). Ralston Reservoir is classified as a "terminal reservoir" <br />because the water stored in the reservoir is fed directly to the Moffat water treatment plant. <br />Water from Ralston Reservoir supplies most of metropolitan Denver's northern suburbs and is also sent to <br />Clear Creek to replace downstream flows that Denver Water withdraws from the Upper South Platte River. <br />The source of water to Ralston Reservoir includes flows from the Ralston Creek drainage combined with <br />water from the western slope and the South Boulder Creek watershed (Figure 8-2). Rainfall and snow melt <br />from the western slope collect through natural channels and flow toward the Winter Park/Fraser area. From <br />Winter Park and Fraser, the water flows through the Moffat Tunnel under the continental divide. After <br />exiting the tunnel on the east side of the continental divide it continues through South Boulder Creek, <br />where it is stored in Gross Reservoir. Water released from Gross Reservoir travels by gravity through <br />natural streams and man-made canals to Ralston Reservoir. <br />Ralston Reservoir has a capacity of 10,749 acre-ft (3,502.6 million gallons [MG]) which is approximately <br />one-fourth the capacity of Gross Reservoir (41,811 acre-ft, 13,624.2 MG) (Denver Water, 2009). Denver <br />Water allows no public access or recreational activities on Ralston Reservoir. The reservoir site and the <br />area immediately surrounding it are fenced to limit access, and on-site caretakers discourage people from <br />violating these rules and provide timely response to any security breaches. <br />Water that exits Ralston Reservoir is delivered to the Moffat water treatment plant via Denver Water's <br />Conduits 16 and 22. The water is treated at the Moffat plant distributed to Denver Water customers. <br />4109C.100731 <br />Whetstone Associates