Overview

Hyatt Dam is on Keene Creek, east of the Cascade Divide approximately 27 miles southeast of Talent, Oregon. It is an earth and rockfill structure having a structural height of 53 feet and a crest length of 775 feet. The total capacity of the reservoir is 16,200 acre-feet (active 16,200 acre-feet).

Hyatt Dam was constructed by the Talent Irrigation District in the early 1920’s for irrigation storage. In 1960, the Bureau of Reclamation rehabilitated the dam, constructing fish screens and recreation facilities as a part of the Talent Division..

Geology

The upper Keene Creek Drainage basin is situated in an area composed of a thick, gently dipping series of volcanic rocks of early Tertiary age, known as Volcanics of the Western Cascades. The series consists of thin, rather extensive, black glassy lava flows interbedded with tuffs, breccias, agglomerate, rhyolite, andesite and basalt. Some of the layers of Tuff, breccia and agglomerate are reddish to brownish; but many range from greenish-gray to tan, while others are dirty white. Most of the fragmental materials show little or no sorting, but in places thinly laminated beds, evidently water sorted, can be found. The beds are tilted. The regional strike is about N 45 degrees W and the dip is 10 to 40 degrees NW. The series of lava flows and fragmental layers may be several thousand feet thick. In places the volcanics have been intruded by dikes and small stocks ranging in composition from granite and decite porphyry to diorite. Most of the rock is thoroughly jointed and deeply weathered. Many of the layers or lenses of Tuff, breccia and agglomerate are very poorly cemented or welded together. The Tuff layers weather to a stiff, sticky, impermeable clayey soil, which shrinks and cracks on drying and swells greatly when immersed in water. Some samples of moderately firm tuff disaggregate or immediately break into silt size particles when immersed in water.

General

Dimensions

Hydraulics & Hydrology