Dams

Of all water infrastructure, dams are probably the most apparent – and impressive.

There are almost 900 recorded dams in Oregon. Over 65% are privately owned, and over 55% are for irrigation. Dam building in Oregon began in the late 1800s, and dam construction reached its peak in the 1950s and 60s.

Dam Density

Dams fundamentally change the environment of their surrounding watersheds. They reduce flow, alter the habitats of freshwater organisms, and affect the amount of sediment that is transported by the river. At the same time, the presence of dams can reduce flood severity and provide water storage. The basins outlined in this map represent the watersheds of many of the largest rivers in Oregon.

Risk and Hazards

Each dam represents a potential hazard. Dam risk is a measure of the amount of economic damage a dam failure would cause.

Low Hazard

dams are likely not to result in loss of life or the destruction of other infrastructure.

Significant Hazard

dams still offer a low likelihood of death, though they do have the potential to destroy or flood infrastructure (roads, power lines, etc.)

High Hazard

dams have a strong likelihood of death and the destruction of buildings and infrastructure.

Dam Removal

Over 30 dams in Oregon have been removed. Many of the dams were removed due to lack of use and pressure from NGOs. Depending on the size of the dam, removal can be a dangerous and very expensive process. Studies have shown surrounding ecosystems are quick to recover after dams are removed.

Hydropower

Over 40% of Oregon's electricity is hydroelectric power produced by dams. Flowing water drives a water turbine and a generator, producing usable electricity. The first hydroelectric dams in Oregon were built in the 1930s and 40s, beginning with Bonneville Dam on the Columbia River. Many of the federally operated dams were constructed by the Army Corps. of Engineers and administered by the Bonneville Power Administration.

Bridges

While dams are an attempt to control waterways, bridges are a reaction to them. The bridges included in this map all cross waterways, and do not include those that are federally owned. Bridges can be a barrier to fish passage, and the failure of a bridge can have major effects on surrounding ecosystems and infrastructure. Bridges that are deemed structurally deficient are eligible for funding for updates or replacement.