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.
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.
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 (caltrout.org)
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