Hagerman Fossil Beds National Monument - Rivers and Streams

Hagerman Valley lies within the central Snake River Plain region of the eastern portion of the Columbia Plateau physiographic province. The Snake River flows west, then north, through this valley and scribes the eastern boundary of the Monument, a shoreline distance of approximately 7 miles. The entire length of the Snake River through the Monument is part of the Lower Salmon Falls Reservoir, the dam for which is located a short distance downstream from the monument. Another dam, the Upper Salmon Falls, is approximately 1 mile upstream from the Monument.

East of the river is the Hagerman Bench, which is crossed by irrigation ditches with little natural runoff. The only major natural drainages into the river are spring-fed Riley Creek and Billingsley Creek. Irrigation ditches contain and direct most of the remaining surface runoff and water from the many springs along the basalt cliffs to the east, and carry it through canals to the river. A few small man-made lakes and ponds exist back from the river. Numerous lakes, ponds, and swampy areas occur at the southern end of the bench.