Salmon Lake Dam

Overview

Salmon Lake Dam is an earthfill structure 54 feet high, and has a volume of 195,000 cubic yards. The total active reservoir capacity of Conconully Lake is 15,700 acre-feet (active 10,500 acre-feet). The spillway is a siphon type with a capacity of 400 cubic feet per second. The outlet works is a conduit controlled by two gates. A small diversion headwords structure on Salmon Creek diverts the flow into the reservoir through a short feeder canal.

In July 1998, a reservoir operating restriction to elevation 2314 feet was imposed on Conconully Lake as an interim risk reduction measure pending structural modifications to address seismic safety concerns. This reduces the active reservoir capacity to 7,400 acre-feet.

Geology

Salmon Lake Dam is founded on the left abutment against rock. The embankment dam across the valley floor and in the right abutment is founded in such materials as silt, sand and gravel, including boulders. The outlet works and spillway are founded on metamorphic sedimentary rock (gneiss).


General
RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
StateWashington
CountyOkanogan
ProjectOkanogan
Dam TypeZoned Earthfill
Reservoir Conconully Lake
WatercourseOffstream Storage
Location
Longitude-119.74496
Latitude48.56036
Original Construction1919-1921
Modified Construction
National ID NumberWA00291
Hydrologic Unit Code

Dimensions
Structural Height54.0 ft
Hydraulic Height (Normal Operating Depth at Dam)40.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation2324.7 ft
Crest Elevation2325.5 ft
Crest Length1260.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis2276.00 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)2318.68 ft
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)2282.10 ft

Hydraulics & Hydrology
Total Water Storage at Elevation10,500 ac-ft
Maximum Water Surface Elevation
Normal Water Surface Elevation2318.68 ft
Spillway TypeUngated Siphon
Auxiliary SpillwayNo
Spillway Capacity at Elevation400 cfs at 2324.7 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation500 cfs
Diversion Capacity at Elevation
Drainage Area6.4 sq mi
Hydrometeorological Report (HMR)HMR 57
Probable Maximum Flood (PMF) Report

Contact Information
Owner
TitleArea Office Manager
OrganizationColumbia-Cascades Area Office
Address1917 Marsh Road
CityYakima, WA 98901-2058
Phone (Fax)509 454-5611
Phone (Office)509 575-5848 x202
Operator
OrganizationOkanogan Irrigation District
Address37 A Douglas Road
CityOkanagan, WA 98840
Phone (Office)509 826-1250


Last updated: Jul 13, 2009