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Rivers & Watersheds

During Orca Month in 2022, through stories and videos, we'll explore some of the watersheds and rivers that are essential to Pacific Northwest salmon and vitally important to the endangered Southern Resident orcas and a healthy marine ecosystem. 


  • Colleen Weiler and Cindy Hansen

We have now arrived at the southernmost range of the Southern Resident orcas, and we will be highlighting the river systems that are important for their winter and spring diet.

Sacramento River

California map. ©Elizabeth Person

Klamath River

The Klamath is a “backwards” river that starts in the high desert and flows toward the Cascade Range and Klamath Mountains, while most rivers start in the mountains and run through increasingly developed areas to the ocean.

The Klamath flows 257 miles through both Oregon and California, and the watershed is the size of Massachusetts and Connecticut combined. Most of the development on the river is in the upper basin, while the lower basin is more rural and less altered, and also home to Klamath Basin Tribes, including the Yurok and Klamath.

Klamath River salmon was historically an important food source for Southern Resident orcas. Spring Chinook are found off the coast during the time of year when K and L Pods tend to travel to Northern California, and Fall Chinook are distributed throughout the ocean during the winter foraging period of the orcas.

Klamath River salmon runs were once the third largest on the West Coast of the United States, after the Columbia River and Central Valley, but have significantly declined. Predicted returns for fall Chinook this year are less than half the historical numbers, and spring run Chinook have returned at less than 2% of their historical numbers for the last 25 years. Coho salmon distribution and abundance has been significantly reduced from historic levels and is now found in only 2/3 of the original habitat. These runs are listed as threatened or endangered in the state of California and/or federally.

Four major dams on the Klamath River - one in Oregon and three in California – have blocked salmon migration for 100 years. These dams have collectively impeded waterflow, warmed the river, caused water quality issues, and driven salmon decline. In 2002, a major fish kill was attributed to low water flow and disease outbreak, and in recent years Klamath Basin Tribes have canceled their own fishing seasons due to ongoing poor salmon returns. While the dams impede salmon migration, there has also been significant habitat loss as much of the upper basin has been converted to farmland, which has caused decades of conflict. The controversy over water rights for irrigation vs. fish led to the development of the original Klamath Basin Restoration Agreement in 2010, with the goal of repairing riparian zones in the Klamath basin and removing the four Klamath dams.

Klamath River

Map of the Central Valley's four major regions.

Central Valley

The Central Valley watershed is 60,000 square miles, over 1/3 of California. It has three major drainage systems, the San Joaquin River, which flows northwest for 365 miles, and Sacramento River which flows south for 447 miles. These two rivers meet in the Sacramento-San Joaquin Delta near San Francisco Bay. The Valley is the most productive agricultural region in California and one of the most productive in the world.It includes multiple major cities and a heavily developed river system with dams, canals and pumps for irrigation.

Salmon in the Central Valley, which provide a food source for Southern Resident orcas in the winter and spring, face many challenges. Once numbering in the hundreds of thousands, many runs have declined to a fraction of their historical numbers. Spring Chinook, which were historically the most abundant, are listed as threatened under the Endangered Species Act.

The unique Winter-run Chinook is listed as endangered and is one of NOAA's Species in the Spotlight. The population numbered nearly 100,000 in late 1960 but in recent years has fallen below 10,000 with only a few hundred fish in some years.

Threats to these salmon include habitat loss due to development and dam construction, pesticide use, and climate change leading to drought. The Central Valley Project is a federal power and water management project which regulates and stores water in reservoirs through a system of twenty dams, plus canals, aqueducts and pump plants.

Salmon cannot pass the biggest dams, Shasta and Folsom Dam, which are too high with reservoirs too large even for fish ladders. The project has caused major environmental changes, including salmon decline, alteration of the rivers and wetlands, and significant impacts on Tribes.

To learn about efforts to restore and recover salmon populations in the Central Valley, please visit: Central Valley Salmon Habitat Partnership | California Trout (


  • Colleen Weiler and Cindy Hansen

For our final week of Orca Action Month’s “Stream to Sea” we continue down the coast to the southern range of the Southern Resident orcas.

View of Cannon Beach in Oregon with Haystack Rock in the background. ©Marisa Estivill

Willamette River:

The Willamette River in Oregon is part of the Columbia River Basin, contributing 15% of the Columbia’s average annual flow. It flows north for 187 miles and is the largest watershed in Oregon, draining 11,487 square miles. Willamette River spring Chinook are part of the Columbia Basin spring returns and therefore were historically important to Southern Resident orcas.

The Willamette Valley is home to 2/3 of Oregon’s population and it has been heavily impacted by development, urbanization, and industrialization. Pollution is a major concern with high levels of heavy metals, PCBs and pesticides, particularly in the section around Portland which was designated a Superfund site in 2000.

The river is heavily dammed, with 15 large dams and multiple smaller ones on some of the river’s tributaries. The primary function for most of these dams is hydroelectricity, while some provide important flood control and water storage. Poor fish passage at these dams, along with loss of habitat, have negatively impacted salmon. While historical abundance was close to 300,000 spring Chinook, recent averages are fewer than 5000 fish.

In 2008, Willamette Riverkeeper designated the full length of the river as the Willamette River Water Trail, which was then made official and expanded by the National Park Service in 2012.

Significant habitat restoration projects have taken place along the river, and the Willamette River Greenway System now includes over 10,000 acres along the river, most owned by Oregon State Parks.

Rogue River Canyon in southwest Oregon. Creative Commons

Rogue River Watershed, USGS, Public domain, via Wikimedia Commons

Rogue River:

The Rogue River in Southwest Oregon flows 215 miles from the Cascade Mountain Range to the Pacific Ocean and drains 5156 square miles. The river contains several salmon and steelhead runs, including spring and fall Chinook, summer and winter steelhead, and Coho. Both spring and fall Chinook salmon are included in the Southern Resident Killer Whale Priority Chinook stocks report, and spring Chinook returns overlap when the whales are primarily off the Oregon Coast in the late winter and early spring. Coho in the Rogue River are currently listed as threatened under the Endangered Species Act, and spring Chinook are “potentially at risk.”

While returns are still below desired target levels and fluctuate on an annual basis, generally the status of Spring Chinook is gradually improving.

The river has a long history of dam construction and removal, including a legendary incident involving an early fish-blocking dam that was blown up by vigilantes who were upset by the impacts to salmon. Concentrated dam removal efforts began along the river in the early 2000s, and by 2009, all but one of the main-stem dams had been removed. The one remaining is the William L. Jess Dam which is used for flood control and hydroelectric. It lies 157 miles inland and there are no salmon above that dam. Current ongoing issues in the Rogue River include pollution from stormwater and wastewater runoff, climate change and drought. Since flows in the river are generally quite low, extremes from climate change can be devastating.

The Rogue River is one of the original eight rivers included in the Wild and Scenic Rivers Act of 1968, which is meant to preserve rivers with outstanding natural, cultural, and recreational values in a free-flowing condition. In 2019, 140 additional miles of tributaries were added to the designation.


This week, we continue further down the coast to explore the Columbia-Snake Rivers and their connection to northwest salmon and Southern Resident orcas.

Historical salmon data for The Columbia and Snake Rivers estimates that 10-16 million wild salmon and steelhead entered the Columbia River Basin to spawn, annually, with 2-4 million more utilizing the Snake River watershed. The Columbia River Basin was once home to the largest runs of Chinook salmon in the world, and roughly half of those Chinook returned to the Snake River in the spring and fall seasons about 200 years ago. Today, less than 1 million fish return to the Columbia River, and fewer than 60,000 wild fish return to the Snake each year.

What began the downfall of salmon populations in this river system?

Largely, the establishment of salmon canneries in 1867 was the first cause of decline in wild salmon populations. In 1879 it was reported that over half a million salmon, with an average weight of 22 pounds, were caught and canned in a single season. At the turn of the century, widespread concern for catch rates of salmon caused the people of Oregon to pass two laws limiting fishing on the Columbia and other rivers. While efforts to curb overfishing (by also banning seine netting) continued into the late 1940s, major modifications to the Columbia and Snake Rivers were also in progress in the form of dams and hydrosystem facilities to generate power, provide flood control, and irrigation options for farming.

Hydrosystem Complexities for salmon on the Columbia-Snake River: Dams and Salmon Don’t Mix

Dams built in the 1930s and 1950s along the Columbia River, and dams built in the 1960s and 1970s along the Lower Snake River, have impeded salmon from reaching their northernmost and easternmost spawning sites, since. By 1986, Snake River Coho were extinct. Today, all surviving Snake River salmon populations are listed under the Endangered Species Act and threatened with extinction. Per the Endangered Species Coalition, “On average, there is a major dam every 72 miles in the Columbia River Basin. The upper stretches of the Columbia and the Snake rivers are impassible at the Chief Joseph and Hells Canyon dams, respectively. But salmon can navigate past some other dams.

Four federal dams managed by the Army Corps of Engineers on the lower Snake are built with fish ladders for returning adult salmon, but out-migrating juveniles (smolts) have a very difficult time getting to the ocean.”

The nine dams along the Columbia prior to reaching Chief Joseph dam, and eight dams along the Columbia-Snake prior to Hells Canyon present massive challenges to both inbound and outbound salmon. Out-migrating salmon smolts have a perilous journey, as they must navigate through a series of hydrosystems, dam turbines, sluiceways, stagnant reservoirs, warming waters, contaminants, and various predators before reaching the Pacific Ocean.

Even if a juvenile salmon manages to reach the Pacific Ocean against these odds, there may still be ramifications leading to mortality due to the stress of navigating these hydrosystems.

While complex in nature due to a degree of variables, fish Biologists and scientists that have studied Columbia-Snake River smolts have discovered that the hydrosystem stressors experienced by out-migrating juveniles may also likely cause some salmon a delayed mortality. Hydrosystem stress on salmon leads them to delay their development and suppress their immune systems, as more energy is channeled into survival, instead. Entering the ocean in a weakened condition can increase the chance that these salmon will be susceptible to disease, parasites, or may not successfully adapt to the saltwater environment. Even if they make it downstream through each aspect of the hydrosystem, they still may not become a viable specimen in their ocean environment. Which also means they will not become accessible orca food.

Actions To Bring Wild Salmon Back to the Columbia-Snake River System:

According to Wild Orca, “NOAA Fisheries, the federal agency charged with protecting both endangered orcas and endangered salmon, has described the decline of Columbia Basin chinook salmon as, “[p]erhaps the single greatest change in food availability for resident killer whales since the late 1800s...”

Whale and Dolphin Conservation adds, “Breaching the Snake River dams, in combination with increased spill (water flow) through other dams in the Columbia River Basin, provides more certainty of long-term survival and recovery for wild Snake River Chinook salmon than any other measure… Removing the dams and increasing spill would help the river system return to more natural conditions, which can help increase survival of wild Snake River Chinook salmon to the point of rebuilding healthy populations – something that the federal agencies themselves recognized in their recent review of dam operations.”

To read more details about the 2020 Federal EIS Report, follow this link: For first time in 20 years, feds take deep look at hydroelectric dam removal on Lower Snake River | The Seattle Times

Resources: | |,number%20declined%20to%20less%20than%201%20million%20fish. | | |

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