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Return Flow Locations: Ditch seepage and irrigation return flows accrue to Big Dry Creek, <br />Little Dry Creek, Coal Creek, Rock Creek, Boulder Creek (from its confluence with Coal <br />Creek to St. Vrain River), and the St. Vrain River (from its confluence with Boulder <br />Creek to the South Platte River). The engineering analysis for the Louisville water rights <br />transfer showed that return flows may take over 100 years to reach Big Dry Creek <br />however this was disputed by the objectors.3, 4 <br />Measurement Device: Upper Community Ditch diversions are measured near the ditch crossing <br />at Highway 93 using a 12-foot Parshall Flume and Type F recorder and include the total <br />amount diverted through the structure under all associated water rights. <br />HydroBase Data: Daily diversion data for Community Ditch are available through HydroBase <br />from 1950 through 2003 however the daily records appear to be more complete starting <br />around 1985. Diversions are coded separately by source, from, use, and type. Between <br />calendar year 1950 and 2003 the average total annual diversions through the Community <br />Ditch were 5,438 acre-feet per year including all diversions for storage and direct <br />irrigation use. Direct deliveries diverted from the Upper Community Ditch through <br />Marshall Lake to the Lower Community Ditch typically occur in May through July, <br />peaking in June during the height of the snowmelt runoff season. <br />2) Marshall Lake (Structure 0604212) <br />Marshall Lake is an off-channel storage facility located southeast of the City of Boulder and is <br />the primary storage facility in the FRICO -Marshall Lake Division. Direct flow and storage <br />water are conveyed to Marshall Lake from South Boulder Creek and Dowdy Hollow through the <br />Upper Community Ditch. Water was originally released from Marshall Lake directly to the <br />Lower Community Ditch. In the early 1980's, the City of Louisville installed a new outlet works <br />and pipeline to convey all of the Marshall Lake releases for both FRICO and the City of <br />Louisville past the Marshall Landfill. The City of Louisville water connects to the Louisville <br />Pipeline and continues to Louisville. The agricultural water is diverted into the Lower <br />Community Ditch for use within the FRICO -Marshall Lake Division and can also be conveyed <br />to a series of smaller operating reservoirs including McKay Lake, West Lake, and Section 19 <br />Reservoir. The Marshall Lake Division also receives a small amount of direct flow water <br />conveyed from Clear Creek and Ralston Creek through the Church Ditch. Historically, FRICO- <br />Marshall had direct rights on Coal Creek and Rock Creek, but these may have been relinquished. <br />When there are "free" river conditions, water can physically be diverted from Coal Creek. <br />Capacity: Marshall Lake was enlarged around the 1900's from 1,349 acre-feet to around 10,000 <br />acre-feet. The current capacity is estimated to be 9,655 acre-feet. Dead storage is less <br />than 300 acre-feet. The elevation at the top of the dam is about 5,710 feet (gage height <br />70.6 feet) and the elevation of the spillway is at about 5,704 feet (gage height 64.6 feet). <br />Area/Capacity Data: The capacity data shown in Table 1, provided by the Water <br />Commissioner, are based on an unknown date of survey. The capacity data presented <br />in Table 1 do not include the less than 300 acre-feet of dead storage. <br />FRICO_Marshall.doc 5 of 12 <br />