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PHYSICAL INFORMATION <br />The major structural elements included in the City of Longmont's water resources system are the <br />North and South Pipelines, Ralph Price Reservoir (aka Ralph Price Reservoir), Union Reservoir, <br />Southern Water Supply Pipeline from Carter Lake Reservoir, and the City's wastewater <br />treatment plant (WWTP). Other storage units and ditch systems (including Pleasant Valley <br />Reservoir under the Rough and Ready Ditch, McCall Lake and Independent Reservoir under the <br />Longmont Supply Ditch, and Lake McIntosh under the Oligarchy Ditch) in the basin are also <br />used in the operation of the City's water supplies. These ditch systems have been identified as <br />key structures for modeling efforts and are discussed in the Task 3 Overall Task Memorandum <br />and Task 3 -Water District S Meeting Notes. Information related to the Southern Water Supply <br />Pipeline and Carter Lake, owned and operated by the NCWCD, is presented in the Task S <br />Memorandum Northern Colorado Water Conservancy District and the Colorado-Big <br />Thompson Project. The history, operations, current specifications, and available HydroBase data <br />of the other elements of the City's water resources infrastructure are summarized below. <br />1) North Pipeline (Structure ID 0500511) <br />The North Pipeline was constructed in the early 1900s on the North Fork St. Vrain Creek and <br />provides upper basin water supplies via gravity to the City of Longmont's North treatment plant. <br />The North Pipeline diversion structure is located above the Town of Lyons and consists of a 35- <br />foot concrete gravity dam structure. The North Pipeline supplies water to a City-owned <br />hydropower plant located south of the North Fork, above the confluence of the North Fork and <br />South Fork. Water from the power plant is temporarily held in a small after bay pond (the North <br />St. Vrain sedimentation pond) to maintain sufficient head prior to delivering water to the North <br />treatment plant. The North treatment plant was constructed in the late-1960s and has an <br />operating capacity of about 10 million gallons per day (mgd). <br />Specifics regarding the North Pipeline include the following: <br />• 30-inch steel pipe <br />• 28.5 cubic feet per second (cfs) capacity <br />• Diversions are measured at the North treatment plant via a Porter Fisher mag meter <br />HydroBase Data <br />The monthly data available in HydroBase over the 1950-2002 period of record pertaining to the <br />North Pipeline include the following: <br />Total River Diversions <br />• Complete record 1954-2002 except for 7 water years (1955, 1959-1960, 1979-1982). The <br />City provided copies of its available diversion records for these periods. <br />• Historic diversions have ranged from approximately 3,000 ac-ft/yr in the 1950s and <br />1960s (mostly C-BT supplies), growing to approximately 12,000 ac-ft/yr over the last 2 <br />decades. <br />• Records of alternate point diversions for Longmont's changed water rights at the North <br />Pipeline are available from the early-1980s for a few structures and from 1990 forward <br />for most of the changed water rights. <br />City of Longmont Operating Memorandum.doc Page 4 of 21 March 2, 2005 <br />