Powder River (Oregon) - Ecology

Ecology

Beaver (Castor canadensis) populations are increasing along the river, with an excellent viewing area just off Oregon Route 7 below Mason Dam, about 14 miles (23 km) from Baker City. There, a colony of beavers constructed a large dam easily viewed below the footbridge adjacent to the paved parking area. Recovered from near extirpation by the Hudson's Bay Company, who tried to create a "fur desert" to discourage Americans from coming to the far western states, benefits of beaver in arid eastern Oregon include creating ponds which along young salmonids to grow, raising the water table as their ponds recharge groundwater supplies and creating wetlands which trap sediment and pollutants.

The Powder River was once an important spawning stream for Chinook salmon (Oncorhynchus tshawytscha) and Steelhead trout (Oncorhyncus mykiss) coming from the Pacific Ocean. Chinook salmon once migrated by the thousands to spawn in the Powder River and many of its tributaries from its headwaters to the lower end of the North Powder Valley, but that stopped when the Thief Valley Dam was built near North Powder in 1931. The building of two later dams in Hells Canyon on the Snake River – Hells Canyon Dam (1967) and Brownlee Dam also permanently block salmon passage. The Oregon Department of Fish and Wildlife often release Chinook salmon on the Powder River for sportfishing at Mason Dam below Phillips Reservoir.