Fish Lake Dam

Overview

Fish Lake Dam, located 35 miles northeast of Medford, Oregon, on the North Fork of Little Butte Creek is an earth and rockfill structure with a height of 50 feet and a crest length of 960 feet.

Rehabilitation at Fish Lake Dam by the Bureau of Reclamation in 1955 included constructing a new spillway, riprapping the upstream face of the dam, and placing fine fill and grading work on the dam crest. The total capacity is 7,900 acre-feet (active 7,850 acre-feet).

In 1996 and 1997, further work was done on Fish Lake Dam under Reclamation’s Safety of Dams Program. This included installing a rockfill berm on the downstream face of the embankment, modification and extension of the outlet conduit, and constructing a new auxiliary spillway on the right abutment of the dam.

Geology

Fish Lake Dam and reservoir are located within the high cascades physiographic province near the crest of the mountain range. Upstream of the dam the North Fork Little Butte drainage basin flows west from the crest of the Cascades and is defined by Mt. McLaughin to the north of the reservoir and Brown Mountain, a small shield volcano located to the southeast of Fish Lake. The left abutment of Fish Lake Dam consists of blocky, andesite lava flow erupted from Brown Mountain (Qbm) subsequent to the retreat of the Pleistocene glaciers. The andesite is dark gray with fine grained ground mass and scattered vesicles. The lack of notable phenocrysts within the ground mass distinguishes the Brown Mountain andesite from the underlying Fish Lake lavas (Qfi). The Brown Mountain andesite is divided into dense central unit of the flow and the upper and lower breccia. The central zone is fresh to slightly weathered, intensely to slightly fractured, hard and dense. The breccia (Qbmb) is an intensely to moderately weathered, moderately hard to soft, vesicular andesite that is moderately to intensely fractured.


General
RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
StateOregon
CountyJackson
ProjectRogue River Basin
Dam TypeZoned Earthfill with Rockfill
ReservoirFish Lake
WatercourseNorth Fork Little Butte Creek
Location 35 miles northeast of Medford, Oregon
Longitude-122.348
Latitude42.3781
Original Construction1902-1908
Modified Construction1922-1923; 1955-1956; 1996
National ID Number OR00021
Hydrologic Unit Code

Dimensions
Structural Height50.0 ft
Hydraulic Height (Normal Operating Depth at Dam)28.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation4641.5 ft
Crest Elevation4649.0 ft
Crest Length960.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)4641.5 ft
Top of Inactive Conservation Pool (Elevation)4615.0 ft
Top of Dead Storage Pool (Elevation)4613.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation 7,836 ac-ft
Maximum Water Surface Elevation
Normal Water Surface Elevation4641.5 ft
Spillway Type
Auxiliary SpillwayYes
Spillway Capacity at Elevation2,330 cfs at 4649 ft service (crest elev. 4641.5 ft)
Auxiliary Spillway Capacity at Elevation5,600 cfs at 4649.0 ft auxillary (crest elev. 4644.8 ft)
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation475 cfs at 4645.0 ft
Diversion Capacity at Elevation
Drainage Area
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
Owner
OrganizationMedford Irrigation District
Address1340 Myers Lane
CityMedford , OR 97501-1270
Phone (Office)541 779-1462
Operator
OrganizationMedford Irrigation District
Address1340 Myers Lane
CityMedford , OR 97501-1270
Phone (Office)541 779-1462


Last updated: Apr 30, 2009