Post Falls Dam
Post Falls Dam is a group of three concrete dams on the Spokane River in Post Falls, Idaho. Built in 1906 on the site of an earlier wooden dam that powered a sawmill, the dams sit where the river flows around the Avista Islands. It is the first of seven Spokane River dams and the most upstream, about nine miles from the river’s source at Coeur d’Alene Lake.
The site began with a 20-foot wooden diversion dam on the north channel, built in 1871 by Frederick Post after buying the land from the Coeur d’Alene Tribe. The sawmill burned in 1902, and Avista (then Washington Water Power) bought the property and built three dams for hydroelectric power. The central-channel powerhouse, completed in 1906, is the one that generates electricity; the other two dams mainly control water flow.
Falls Park on the north bank has been open since the 1990s. It provides information about the site’s history and views of the north-channel dam and spillways.
Key details:
- Middle-channel powerhouse: 431 feet long, 31 feet tall; 6 turbines; about 14.75 MW capacity.
- North-channel dam: L-shaped with one large sluice and eight smaller sluices.
- South-channel dam: 78 feet long with gates about 13 feet high.
- Owner: Avista.
The dam holds back the Spokane River and helps regulate water flow toward Coeur d’Alene Lake.
This page was last edited on 3 February 2026, at 04:11 (CET).