Forests conserve water for irrigation, prevent soil erosion and floods, and maintain the purity of drinking-water sources. Standing timber also serves as a sanctuary for birds and game and furnishes summer range for cattle, horses, and sheep. In the past, these resources suffered from the "cut-up-and-get-out" logging methods employed. Present conservation programs, however, are aimed at safeguarding, through planned use, what is left of the State's forests and, ultimately, in restoring some of the lost woodlands.
Seven national forests lie wholly in Washington, and two others partly in Washington, Idaho, and Oregon. To the west, mainly in the high Cascade region, are the Mount Baker, Snoqualmie, Wenatchee, Chelan, Columbia, and Olympic national forests. In the northeastern section is Colville National Forest and, farther east and extending into Idaho, the Kaniksu National Forest. From the extreme southeastern quarter of the State, Umatilla National Forest extends into Oregon.
The Columbia River, 1,210 miles in length, is the largest stream west of the Rockies and drains an area of 259,000 square miles. At Grand Coulee it has an average volume of about 109,000 cubic feet per second. As a whole, the river is capable of generating more than 8,000000 horsepower in a possible total of 145 plants along the main stream and tributaries. In its course through the State the Columbia has a total fall of about 1,300 feet.
With the Columbia and many smaller rivers dammed by power and irrigation projects, fish were prevented from reaching upriver spawning grounds. Here, too, fruitful remedies have been devised. At Bonneville Dam elaborate fish ladders and locks were constructed, and a daily count was taken of the various species passing over them. Refrigerated, air-conditioned tank trucks remove the salmon trapped below Coulee Dam to spawn elsewhere. Most species of salmon are at least holding their own, except the Chinook, which still appears to be decreasing. In the Columbia River district alone, however, many millions of Chinook eggs are taken annually for artificial hatching.