Snake River sockeye salmon face the most arduous journey of any Idaho fish. Starting as smolts no longer than your finger in the high lakes near Stanley, they swim downstream 900 miles to the Pacific Ocean. From there, they journey for thousands of miles across the Pacific, ranging to Canada, Alaska, and the Bering Sea for nearly two years. When the time is right, they struggle upstream those same 900 miles and climb up 6,500 feet in elevation to get back where they started – Redfish Lake and Pettit Lake, in the heart of Idaho.
Sockeye complete this magnificent migration at the height of the summer months: late July and August. The fish are sensitive to extremely high water temperatures, typically reached at 68 degrees Fahrenheit. Warmer water than this can deplete the sockeye’s energy stores, causing them to slow or halt their journey. Hot water can also foster the growth of dangerous water-borne pathogens that infect sockeye, killing them before they have a chance to spawn the next generation. If it gets hot enough, the water itself can kill fish, exhausting them as they strive to keep cool.
Though the sockeye run isn’t yet complete, this year looks like the continuance of a years-long downward trend. Despite a relatively large number of sockeye that returned to the mouth of the Columbia, only 20% have successfully made it from Bonneville Dam near Portland to the last dam at Lower Granite, near Lewiston. Their journey has been slowed by heat, leaving them vulnerable to disease, predators, and exposure to increasing heat. In summarizing the run thus far, a representative of the Idaho Department of Fish and Game said it’s “not a pretty picture.”
Historically, summer heat provided difficulties, but not insurmountable obstacles: near the turn of the 20th century, 25,000 sockeye returned annually to lakes in the Sawtooth Valley (Redfish, Pettit, Alturas, Stanley, Yellow Belly, and Hell Roaring). Even more came back to Oregon’s Wallowa Lake, the Payette River system in Idaho, and Warm Lake at the head of the South Fork of the Salmon River. For thousands of years, through many heat waves, droughts, and other climate conditions, sockeye persevered.
That changed when hydroelectric dams were introduced to the Snake and Columbia rivers. The eight dams that modern sockeye must face impound eight huge, stagnant reservoirs. The blocks of warm water contained in these reservoirs routinely warms to dangerous temperatures above 68 degrees, and doesn’t cool quickly. Sockeye once depended on thermal refugia (areas of cold water) and nighttime cooling to migrate safely, but these are no longer present in the lower Snake and lower Columbia reservoirs. Climate change has exacerbated the problem, to nightmarish levels.
2015 was a promising year for Snake River sockeye. After several years of zero returning fish in the 1990s, and the return of the infamous “Lonesome Larry” – a single adult male sockeye in 1992 – work by the State of Idaho, federal agencies, and the Shoshone-Bannock Tribes had resulted in several hundred wild fish returning to Idaho in 2014. Even more fish came to the mouth of the Columbia in 2015, but they were greeted by an extreme heat wave and walls of scorching water behind each dam. A massacre ensued: 96% of the Idaho-bound fish died before reaching the 8th dam at Lower Granite. Just 1% made it successfully to Redfish Lake. This set the sockeye restoration program back significantly and revealed the dire threat posed by dams and a warming planet to Idaho’s iconic fish.
In studying the issue after 2015, it became clear that problems for sockeye weren’t limited to only these extreme years. High water temperatures routinely killed hundreds of Snake River sockeye before they could get home. Because wild sockeye have been listed under the Endangered Species Act since 1991, it’s illegal to harvest them, and dam operators at the US Army Corps of Engineers (Corps) may only “incidentally” kill a percentage of sockeye through dam operations each year. But in 10 of the last 11 years, the Corp’ dams and reservoirs killed many more sockeye than they were allowed to. Heat pollution caused by the dams is a consistent problem, and it’s only expected to get worse as years like 2015 become more common.
Given this, in mid-July ICL and our partners at Columbia Riverkeeper, the Northwest Sportfishing Industry Association, and Idaho Rivers United sent a 60-day Notice of Intent to Sue letter to the Corps, asking the Corps to remedy the problem by reducing, mitigating, and/or eliminating hot water conditions caused by the lower Snake River dams. We believe the only way to effectively do this is to breach the four dams and restore a free-flowing river, providing refuge and hospitable migration conditions for Snake River sockeye salmon.