OREGON RESERVOIR REPORT

Last Updated: December 5, 2025

Oregon has over 1,200 reservoirs and dams, with the largest being the Owyhee Reservoir, which can hold up to 1.1 million acre-feet of water. Other major reservoirs include the Detroit Reservoir, Wickiup Reservoir, and Crane Prairie Reservoir. The sources of water for these reservoirs include the Columbia River, Snake River, Deschutes River, and their tributaries. The snowpack in the mountains is a crucial factor in filling these reservoirs, with the Cascades and Blue Mountains being the primary sources. Record levels for reservoirs and dams vary depending on location, but generally occur during periods of heavy precipitation or snowmelt. Drought conditions are also a concern, as low snowpack and reduced streamflow can impact water availability for irrigation and recreation. Seasonal trends in precipitation and snowpack influence water levels in reservoirs, with lower levels typically seen in late summer and early fall. Overall, the hydrology in Oregon is heavily influenced by the state's topography, with water sources being mainly mountain-fed and dependent on snowpack accumulation.

Oregon has over 1,200 reservoirs and dams, with the largest being the Owyhee Reservoir, which can hold up to 1.1 million acre-feet of water. Other major reservoirs include the Detroit Reservoir, Wickiup Reservoir, and Crane Prairie Reservoir. The sources of water for these reservoirs include the Columbia River, Snake River, Deschutes River, and their tributaries. The snowpack in the mountains is a crucial factor in filling these reservoirs, with the Cascades and Blue Mountains being the primary sources.

Record levels for reservoirs and dams vary depending on location, but generally occur during periods of heavy precipitation or snowmelt. Drought conditions are also a concern, as low snowpack and reduced streamflow can impact water availability for irrigation and recreation. Seasonal trends in precipitation and snowpack influence water levels in reservoirs, with lower levels typically seen in late summer and early fall. Overall, the hydrology in Oregon is heavily influenced by the state's topography, with water sources being mainly mountain-fed and dependent on snowpack accumulation.