Flood elevations for the Sooes River at proposed fish hatchery, Clallam County, Washington; a surface-water site study

Water-surface elevations were derived for various combinations of selected river discharges and tide elevations along a reach of the Sooes River 3 miles upstream from the mouth at the site of a proposed fish hatchery in Clallam County, Washington. Flood-frequency analyses determined river discharges having exceedence probabilities of 1, 2, 4, 10 and 20 percent (100-, 50-, 25-, 10-, and 5-year recurrence intervals) and tide elevations having exceedence probabilities of 1 and 50 percent (100- and 2-year recurrence intervals). A relationship was developed for determining river water-surface elevation for different combinations of river discharge and tide elevations. Seven different combinations of river flood-plain conditions that may be expected to occur during and after construction were simulated and water-surface elevations determined by use of the step-backwater computer program.