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I I I I I I I I I I I I I I I I I I I EXECUTIVE SUMMARY North Poudre Reservoirs No. 5 and No. 6 are located In Larimer County approxi- mately I mile south and 1/2 mile west of Wellington, Colorado. The dams were originally constructed In about 1890 and both dams have been raised and modified at least once following the Initial construction. The reservoirs are filled by an appropriation of water from the Cache La Poudre River by means of the Poudre Valley Ditch. Some runoff Is captured out of Dry Creek and the drainage Immediately above the reservoir. North Poudre Reservoir No. 6 Is Impounded by two earth dams with a maximum height of 42 feet and a total crest length of approximately 2000 feet. The dams Impound a reservoir of 9968 acre-feet at a normal pool elevation of 5158.4 feet USGS or Gage Height 36 feet. The existing outlet works consists of 2-36 Inch concrete box conduits and gate well that are In a state of disrepair and are no longer operational. The State EngIneer has Imposed a zero storage restrIction on the reservoir due to the condItion of the outiet. The control gates have been opened and the stems removed from the control gates to ensure no storage Is maintaIned In the reservoir. The reservoir does not have an emergency spillway and the releases are controlled solely by the outlet conduit. North Poudre Reservoir No. 5 Is Impounded by one earth dam with a maximum height of 34 feet and a total crest length of approximately 2100 feet. The dam Impound a reservoir of 8398 acre-feet at a normal pool elevation of 5176.4 feet USGS or Gage HeIght 30 feet. Releases from the reservoir are through a 2'-4" by 3'-0" masonry conduit that empties Into a feeder ditch on the south end of the reservoir. The reservoir has one 250 foot emergency spillway set approximately 6-feet below the dam crest. The reservoir Is currently restricted to Gage Height 21 feet due to seepage at the downstream toe of the dam around the outlet conduit. The storage level of both reservoirs has been restricted by the Colorado State Engineer's Office (SEO) since 1978. ThIs restriction reduces the reservoir storage capacity of both reservoirs by 13,658 acre-feet, from a maximum of 20,546 acre- feet. On January 9, 1992 the North Poudre Irrigation Company Board of Directors at their monthly meeting passed a resolution to conduct a feasibility study for the renovation of Reservoir No. 5 and No. 6 and to apply for funding of the project through the Colorado Water Conservation Board(CWCB). That funding was approved by the CWCB and the Colorado Legislature In 1992 contingent on the completion and acceptance of the feasibility study. This report was prepared by SMITH GEOTECHNICALIEnglneerlng Consultants to fulfill the requirements of the CWCB to complete the application for funding. I.