Water is capable of many extraordinary things. Throughout history, humans have attempted to control or utilize the power of water. In Oregon, water presents both opportunities and obstacles, and we have used infrastructure to exploit both.

Created by Gareth Baldrica-Franklin, Institute for Water and Watersheds, Oregon State University


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 Storage in Thousands of Acre-Feet

<1   1-50  51-100  101-500   >501 

Year Completed

Pre-1910   1910-1929  1930-1949

1950-1969  1970-1989  Post-1990

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Dams per Basin

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.

# of Dams


31 - 50

16 - 30

6 - 15

< 5

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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 Height in Feet

<25   26-100  101-200  201-300   >301 

Hazard Rating

Low        Sig.       High

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Dam Removal

Over 30 dams in Oregon have been removed. Many of the dams were removed due to lack of use and pressure from non-profit organizations. 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.

Dam Height in Feet

<10  11-20  21-40    40+

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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.

Power Capacity in Megawatts

<10   11-50   51-100  101-1000   >1001 


Federal    Municipal  Other

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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.

Bridge Condition

Not Deficient

Structurally Deficient/Obsolete

No Data

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