< Back to Recommendations

Recommendation: 8

Status: Underway

Increase spill to benefit Chinook for Southern Residents by adjusting total dissolved gas allowances at the Snake and Columbia River dams.


Action 1

Direct the Washington Department of Ecology to increase the standard for dissolved gas allowances from 115 percent to up to 125 percent to help determine the best level for spills over the dams that will benefit salmon.

Action 2

Coordinate with the Oregon Department of Environmental Quality to align standards across the two states.

Action 3

Rigorously monitor impacts to the fish and other wildlife in the water to ensure the new spill levels cause no harm.

Action 4

Minimize revenue losses to other wildlife programs that benefit from hydropower.

Implementation Details

The Department of Ecology should move to immediately eliminate the current 115 percent standard for the forebay of the eight dams on the lower Snake and lower Columbia Rivers and adjust total dissolved gas allowances to up to 125 percent, as measured at tail races.

The intent is to create flexibility to adjust spill regimes, using the best available science, to benefit Chinook salmon and other salmonids. Ecology should work as expeditiously as possible with the Washington Department of Fish and Wildlife and Oregon Department of Environmental Quality to align at this level.

Any new spill levels tested through this flexibility in spill regimes should be monitored and adaptively managed to minimize any negative effects on resident and anadromous fish species.

Recent Progress

In December 2019, the Washington Department of Ecology changed a rule to allow up to 125 percent total dissolved gas in the lower Snake and lower Columbia Rivers. The rule was approved by the U.S. Environmental Protection Agency and has allowed flexible spills during the 2020 and 2021 spring spill seasons to benefit Chinook. An agreement in a lawsuit over the federal Columbia River System biological opinion will allow flexible spills again in 2022.

More details may be found in the progress reports in theĀ resources library.