Determination of Upstream Boundary Points on Southeastern Washington Streams and Rivers Under the Requirements of the Shoreline Management Act of 1971

ABSTRACT Regulation of the shorelines of the State of Washington, as mandated by the Shoreline Management Act of 1971, requires knowledge of the locations on streams and river reaches where specific regulatory criteria are satisfied. The U.S. Geological Survey conducted a study in 1971 to determine the upstream boundary points of these reaches for many of the State's streams and rivers. Updated upstream boundary points were determined in the current study for all the streams and rivers in southeastern Washington that fall under the jurisdiction of the Shoreline Management Act of 1971. Upstream boundary point locations where the mean annual discharge equals 20 ft3/s (cubic feet per second) were determined for 149 streams. In addition, upstream boundary point locations where the mean annual discharge equals 200 ft3/s or the drainage area equals 300 square miles were determined for 22 rivers. Boundary point locations were determined by application of multiple-linear-regression equations t