PROJ00318

• Contract/PO #: C153618
• Contractor Name: Greeley, City of
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: SB 87-15
• Loan Projects - Doc Type: Feasibility Study

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INTRODUCTION

Peterson lake Dam is an earth embankment dam with a maximum height of 57 feet
and a crest 1 ength of 175 feet at e1 evati on 9517. It impounds a reservoi r,
when full, of 1,252 acre-feet at the normal maximum water surface elevation of
9510, of whi ch 1183 acre-feet is acti ve storage and 69 acre-feet is dead
storage. The dam is located on a small unnamed tributary to the Cache la
Poudre River, approximately eight miles upstream of the Spencer Heights
Resort. The dam was constructed in the early 1920' s by the Mountai nand
Plains Irrigation Company for irrigation supply. The dam has been repaired
and modifi ed over the years, most si 9nifi cantly in 1972 and 1973 when the
crest was lowered by six feet, service and auxiliary spillways were added, and
the outlet works were repaired. The dam's operating level has been restricted
to elevation 9498 (gage height 20.0 ft.) since August 15, 1982 by the Colorado
State Engineer's Office (sEO). This restriction was imposed due to excessive
seepage and the hi gh phreati c surface wi thi n the dam resulti ng in potenti a1
instability of the downstream toe. The City unilaterally imposed a zero
storage restriction in October 1985, until the results of the September 1985
embankment drilling could be fully analyzed and a safe storage level
determined. Morrison-Knudsen Engineers, Inc. (MKE) was contracted by the City
of Greeley in June of 1986 to study the feasibility of rehabilitating the
dam. The study is partially financed by the Colorado Water Conservation Board
(CWCB).

The following feasibility report contains chapters of general information
pertaining to the site, background information on the City of Greeley,
benefl ts to agri cu1 ture, and the avail abil i ty and util i zati on of water from
the project. The plan of development contained in Chapter 5 includes a
discussion of the site inspections, geotechnical investigation, hydrological
analysis, alternatives for rehabilitating the dam, and the selected
feasibility design, as well as the recommended interim level of operation.
The report conc1 udes wi th chapters on the estimated cost of the proj ect and
evaluation of the economics. The report has been prepared in accordance with
the guidelines issued by the CWCB.

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