Mason Dam


Mason Dam is a rolled-earth and rockfill structure 173 feet in height with a crest length of 895 feet. Phillips Lake, impounded behind the dam, covers 2,235 acres and has a total capacity of 95,570 acre-feet (active 90,570 acre-feet) at reservoir water surface elevation 4070.5 feet. There is 17,000 acre-feet of space reserved in the reservoir exclusively for flood control purposes. The remaining 73,570 acre-feet of space in the reservoir is for storage of water for irrigation up to reservoir water surface elevation 4062.37 feet.

RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
Dam TypeRolled Earth and Rockfill
Reservoir Phillips Lake
WatercoursePowder River
Location17 miles from Baker
Original Construction1965-1968
Modified Construction
National ID NumberOR00577
Hydrologic Unit Code

Structural Height173.0 ft
Hydraulic Height (Normal Operating Depth at Dam) 152.5 ft
Top Parapet (Elevation)
Spillway Crest Elevation4070.5 ft
Crest Elevation4082.0 ft
Crest Length895.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis3918.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)4062.374 ft
Top of Active Conservation Pool (Elevation)4050.63 ft
Top of Inactive Conservation Pool (Elevation)3981.5 ft
Top of Dead Storage Pool (Elevation)3975.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation73,570 ac-ft at 4062.37 ft
Maximum Water Surface Elevation
Normal Water Surface Elevation4062.37 ft
Spillway TypeUngated overflow chute at left abutment
Auxiliary SpillwayNo
Spillway Capacity at Elevation1,210 cfs at 4077.25 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation875 cfs at 4070.5 cfs
Diversion Capacity at Elevation
Drainage Area175 sq mi
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationSnake River Area Office
Address230 Collins Road
CityBoise, ID 83702-4520
Phone (Fax)208 383-2275
Phone (Office)208 383-2248
OrganizationBaker Valley Irrigation District
Address3895 Tenth Street
CityBaker City, OR 97814-1424
Phone (Office)541 523-5451

Last updated: Nov 21, 2012