Three Mile Falls Diversion Dam


The Three Mile Falls Diversion Dam is a concrete multiple arch weir which diverts water to the West Division through the West Extension Main Canal. The dam is on the Umatilla River 3 miles south of Umatilla, Oregon, and has a structural height of 24 feet, a hydraulic height of 23 feet, and a crest length of 915 feet. The canal is 27 miles long and has a diversion capacity of 375 cubic feet per second.

RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
ProjectUmatilla Basin
Dam Type
WatercourseUmatilla River
LocationThree miles south of Umatilla, Oregon
Original Construction1914
Modified Construction
National ID NumberOR00588
Hydrologic Unit Code

Structural Height24.00 ft
Hydraulic Height (Normal Operating Depth at Dam)23.00 ft
Top Parapet (Elevation)
Spillway Crest Elevation
Crest Elevation404.30 ft
Crest Length915.00 ft
Crest Width
Base Width
Volume of Dam Construction Materials5100.00 cu yd
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation
Normal Water Surface Elevation
Spillway Type
Auxiliary Spillway
Spillway Capacity at Elevation
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation
Diversion Capacity at Elevation
Drainage Area
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationColumbia-Cascades Area Office
Address1917 Marsh Road
CityYakima, WA 98901-2058
Phone (Office)

509 575-5848 x202

Phone (Fax)

509 454-5611

OrganizationWest Extension Irrigation District
Address840 S. Main St.
CityIrrigon, OR 97844
Phone (Office)541 922-3814

Last updated: Jan 07, 2009