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Reservoir Seepage Information: No studies have been conducted to quantify seepage losses <br />from Ish Reservoir. Ditch company representatives reported that seepage is minimal from <br />the reservoir. The ditch secretary irrigates 300 acres directly north of the reservoir and he <br />reported these lands do not benefit from sub-irrigation from reservoir seepage. Seepage <br />losses, to the extent that they do occur, are conveyed via underground drain the (laid <br />many decades ago) to the Little Thompson River approximately one-half mile east of <br />Highway 287. <br />HydroBase Data: The monthly data available in HydroBase over the 1950-2002 period of <br />record pertaining to the Ish Reservoir include the following: <br />End-of--month contents (see Figure 2). Data missing for water years 1952, 1964-1968, <br />1986, and 1987. These data were not provided by the ditch company. <br />As illustrated by Figure 2, Ish Reservoir fills in about half the years with records. The <br />Boulder Larimer Ditch Company's initial fill of 2,546 ac-ft occurs in about 8 to 9 of <br />every 10 years. These low storage amounts are generally a consequence of limited <br />physical, rather than legal, water supply. The yield per share of Boulder Larimer Ditch <br />Company stock is generally the storage yield. Deliveries to New Ish Ditch shareholders <br />are limited based on the operating rules established in the 1905 agreement. <br />s <br />ooo <br />, <br />~ <br />ooo <br />, <br />6 <br />000 <br />, <br />5 <br />000 <br />, <br />4 <br />000 <br />, <br />3 <br />000 <br />, <br /> <br />= 2 <br />000 <br />, <br />W 2,546 ac-ft <br />1 <br />000 <br />, <br />0 <br />~~ <br />~ ~ ~ ~ ~ <br />Date <br />Figure 2: Ish Reservoir Storage Records <br />Ish Reservoir Outlet Ditches <br />The Old Ish Ditch receives water through an approximately 32-inch outlet pipe located at <br />elevation zero feet (see area-capacity curve in Table 1) on the western end of the dam. The Old <br />Ish Ditch travels about two and one-half miles in an east-northeast direction toward the Baxter <br />Lake drainage. Storage releases to the Old Ish Ditch are measured in a 5-foot Parshall flume <br />below the outlet pipe. The New Ish Ditch receives water through a 40-inch outlet pipe located at <br />Boulder Larimer Ditch Memorandum.doc 7 of 11 October 28, 2004 <br />