BOISE – Juvenile salmon and steelhead migrating out of the Columbia River Basin in unusually high flows this year face a potentially lethal problem in spillways at dams where increased nitrogen in the water can cause tissue-damaging gas bubble trauma.
But fisheries managers say special features at dams meant to reduce nitrogen will help young fish make it to the ocean and predict survival this year will be about average based on previous high-flow years.
Like natural waterfalls, water going over a dam’s spillway increases total dissolved gas in water. That includes nitrogen that can cause bubbles to form inside fish.
The standard for total dissolved gas considered safe for fish is 110 percent, but dams on the Columbia and Snake rivers in recent weeks have been near or above 120 percent.
Local journalism is essential.
Give directly to The Spokesman-Review's Northwest Passages community forums series -- which helps to offset the costs of several reporter and editor positions at the newspaper -- by using the easy options below. Gifts processed in this system are not tax deductible, but are predominately used to help meet the local financial requirements needed to receive national matching-grant funds.
Subscribe to the Coronavirus newsletter
Get the day’s latest Coronavirus news delivered to your inbox by subscribing to our newsletter.