Page:Report of the Oregon Conservation Commission to the Governor (1908 - 1914).djvu/276

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John Day River drains the largest area of any stream rising in the Blue Mountains and although its rate of runoff is low. its total water supply will suffice to irrigate a large area. The proposed John Day project for irrigating lands lying along the south side of Columbia River in Gilliam, Morrow, and Umatilla counties, will involve a very long and expensive canal, but the lands under it become very valuable when irrigated. There are at least three reservoirs any one of which could be developed to control the entire runoff at the site. The waters of the John Day will probably be utilized to the extent of the mean discharge for the three or four lowest suceesiva years, say 1908 to 1911, lass the losses by evaporation, or some 900,000 acre-feet, which will suffice to cover the available land.

Deschutes River, rising in the lava beds which flank the summits of the Cascades and serve as a natural equalizing reservoir, has the most remarkably uniform flow of any stream in the Northwest. It possesses power sites capable of generating near]y one million horse power and has an average runoff of about 5,000,000 acre-feet, of which nearly one-third can be ultimately utilized for irrigation. The average runoff of Deschutes River at Benham Falls during the past seven years has been 1,220,000 acre-feet. The Benham Falls reservoir, the largest storage basin which has been surveyed in the State of Oregon, can be developed to any capacity that the water supply will warrant, and as this river varies only slightly from year to year practically the entire runoff can be utilized.

Crooked River, the large easterly tributary of the Deachutes, drains an area which, although extensive, partakes only in a limited degree of the character of the Deshutes. Its rate of runoff is small, and varies widely from season to season and from year to year. There is an excellent reservoir dam-site, just below the forks of Crooked River above Post, and there are smaller sites on tributaries of Ochoco Creek, which enters the main river at Prineville. The total average runoff of Crooked River is estimated at 310000 acre-feat of which probably 250,000 will ultimately be utilized.

Tumalo and Squaw creeks are tributaries of Deschutes River from the west. They drain only limited areas but their sources are in the high divide of the Cascade range, and their runoff s heavy and well maintained. The waters of Tumalo Creek