NOAA Fisheries’ conserves, protects, and enhances populations of Pacific salmon and steelhead and their habitats that are affected by hydroelectric, water storage, and diversion dams, as well as other marine species in coastal areas affected by hydrokinetic projects. We do this through our authorities under the Endangered Species Act, Federal Power Act, and other laws. Our biologists and engineers ensure fish are able to pass the structures by studying different alternatives and working with partners to implement passage routes that meet their biological needs.

About Dams and Fish on the West Coast

Dams provide electricity, flood control, recreation and transportation as well as water for domestic and agricultural use. However, dams also change the way rivers function, and may interfere with the life cycles of salmon, steelhead, and other animals. They are barriers to juvenile salmon migrating to the ocean, and an obstacle as adult fish return to their natal streams to spawn.

Dams affect the way water moves down a river, by changing the amount and timing of flow, as well as its temperature and chemical characteristics. And because dams transform the upstream habitat from a river into a lake, they change the amount and location of available habitat and significantly alter the salmon’s interaction with predators and competitors.

For salmon to thrive, it is important to provide safe, swift passage past dams for juveniles traveling to the ocean and for adults migrating back to their spawning grounds. There are many types of passage infrastructure in use at and around dams, depending on factors such a dam’s age, size, location and purpose. Sometimes passage facilities are added many years after a dam is built. These are the most common types of fish passage.

Learn more about how dams affect water and habitat

Fish Passage Solutions:

• Adult Upstream Passage, including fish ladders and trap and haul.
• Juvenile Downstream Passage, including passage routes, bypass systems, surface passage structures, floating surface collectors, and new, improved turbines for juvenile downstream passage.
• Other Fish Passage Structures, including culverts, tidegates, and fish screens.

Dams and Fish

• Federal Columbia River Power System
• Willamette Valley Flood Control Project
• Central Valley Dams and Salmon
• Klamath River Project
• West Coast Hydroelectric Projects
• Southern Resident Killer Whales and West Coast Chinook Salmon (PDF, 8 pages)

Affected Species

• Salmon
• Steelhead
• Seals & Sea Lions
• Southern Resident Killer Whales
• Eulachon
• Green Sturgeon

Resources

• Biological Opinions
• Fish Counts in the Columbia & Snake Rivers
• Fish Counts in the Willamette River
• Fish Passage at Northwest Hydroelectric Projects
• California Fish Passage: Frequently Asked Questions
• Fish Passage Guidelines
• Fish Screening Criteria for Pumped Water Intakes (PDF, 4 pages)

Passage Success Stories

• Endangered Salmon Set to Expand Their Range in California’s Central Valley
• Coho salmon return to Oregon’s Grande Ronde
• Dam overhaul improves fish passage, opens window for migration
• Benefits for Wildlife Flow from San Clemente Dam Removal
• NOAA Fisheries assists Olympic National Park in reopening Elwha River
• A River Runs Around it
• Partners set in motion historic venture to reintroduce salmon to the Yuba River
• Removal of diversion dam improves habitat access for migrating fish in California’s Tehama County
• New adult fish facility opens Oregon’s South Santiam basin to threatened salmon & steelhead
• Washington’s Baker River reaches all time record—one million salmon are on their way to the Pacific Ocean
• Removing barrier opens 40 miles of habitat to threatened steelhead in California Creek