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---J -~ Colo. Water Conservation Board September 28, 1989 Page 5 Irril!stion Use 1. 3,500 square-feet per dwelling 2 . Average lawn irrigation water requirement = 2.84 ac-ftIac (34 inches) 3. No credit for return flows from lawn irrigation. It is also assumed that the storage releases from Bear Creek Lake would be used to offset the stream depletions resulting from municipal diversions from Bear Creek by MCMD, i.e., ten percent of the water diverted for in-building uses plus 100 percent of the water diverted for outside irrigation uses. Releases would also be made to cover winter return flow obligations of 22 acre-feet per year for the Robert Lewis Ditch. Using these criteria, an in-house operation study of the available supply (Tables A & B) vs. the municipal demand was made, assuming that MCMD had use of only 50 acre-feet of storage capacity in Bear Creek Lake, a value which corresponds to MCMD's initial request for storage. The results show that about 540 single family equivalent units (SFE) could be supplied. At this level of development, in most years of study, there were substantial spills from the lake because the available supply from the Robert Lewis and Hock-Hocking rights exceeded the demand and the 50 acre-feet of capacity in the lake. However, in the dry period 1954-56, when there was essentially no Robert Lewis water available, the storage was fully utilized and was nearly drawn down to zero. The daily "RELEASE" requirement for the option with 50 acre-feet of storage capacity (540 SFE) is listed in Table 2. A second analysis was made to determine how many SFE could be supplied given the same water supply (Robert Lewis + Hock-Hocking) but with 1 carry-over storage capacity of 650 acre-feet in Bear Creek Lake. This study indicated that about 1,270 SFE could be provided without fully drainirig the storage. This represents about 35 percent of the estimated build-out in the MCMD. Spills from the lake did not occur and there was