The White River Watershed encompasses 349,414 acres. Key tributaries include Jordan, Tygh, Badger, Threemile, Clear and Rock Creeks. The area also includes small drainages to the north of White River that drain from the west into the Deschutes River, including Spring, Wapinitia, and Nena Creeks. White River originates within the Mt. Hood National Forest on the southeastern slope of Mount Hood, which is the highest point in the watershed at 11,291 feet. The White River flows generally east to enter the Deschutes River at river mile 47.5 at an elevation of 789 feet.  Climate varies dramatically across the White River watershed because of its wide range of elevations and associated precipitation patterns. The average annual rainfall varies from 100+ inches on Mt. Hood to 10 inches or less along the Deschutes River. the headwaters of the White River are in the Cascade Crest Montane Forest Ecoregion. The headwaters of Tygh, Threemile, and Badger Creeks are located at lower elevations within the Grand Fir/Mixed Forest Ecoregion. The middle elevations of the watershed are within the Ponderosa Pine/White Oak Ecoregion. The Umatilla Plateau Ecoregion, characterized by bunchgrass prairie with mixed hardwood trees in riparian zones and deep canyons, covers the lower third of the watershed.  Stream flow patterns vary widely throughout the watershed. The upper White River, which is fed by glaciers and persistent snowpack, is characterized by high flows from January through June, followed by relatively high summer baseflows. In contrast, Tygh Creek, which is lower in elevation and does not have persistent snowpack to sustain flows, has relatively low flows during the summer, with spring flooding driven by "rain-on-snow" events. This same flow pattern applies to Badger, Threemile, and Wapinitia creeks. Nena, Winter Water and Oak Springs Creeks originate at lower elevations and accumulate little winter snowpack; their flow pattern is dominated by surface runoff, with some soil infiltration. Storage reservoirs and irrigation diversions also exist on many tributary streams. The White River drainage, for example, contains four reservoirs: Clear, Badger, Rock Creek, and Pine Hollow reservoirs. These reservoirs supply much of the irrigation water to irrigated cropland. Diversion of water for irrigation and storage in Rock Creek an Pine Hollow reservoirs has converted the lower reaches of Gate, Rock and Threemile Creeks from perennial to intermittent streams for much of the year.