Lemhi River Drainage
Irrigation Valves
Irrigation valves, south of Salmon.
The Lemhi River flows 56 miles from the confluence of Texas and Eighteen-mile creeks to the Salmon River at river mile 258.5 at the city of Salmon. The river drains approximately 1,290 square miles and flows through a broad valley of fertile agricultural land between the Bitterroot and Lemhi mountain ranges. The valley includes more than 25,000 acres of land irrigated for hay production and grazing. The principal form of irrigation is flooding from an extensive system of ditches. All major ditches are screened and have bypass systems to prevent fish losses. The river is overappropriated for irrigation and is dewatered in the lower reach during low flow years which impedes adult and juvenile salmon and steelhead migration.

The drainage supports runs of both salmon and steelhead. The amount of spawning habitat has been reduced by stream alterations but is still significant, particularly in the upper reaches.

Native resident trout include rainbow, cutthroat, and bull trout. Brook trout are present in limited numbers.
Written and compiled by Jacqueline Harvey 1999.