[8/28/19] Dam Spills to Help Salmon Migration

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Snake and Columbia river hydropower dams may soon allow more water over the dams to help salmon migration. Taking action to allow more spill over the dams is one of the Southern Resident Orca Task Force recommendationsto the Governor. Salmon runs on the Snake and Columbia rivers include Chinook, the Southern Resident Orca’s primary food. And the Department of Ecology is seeking public comment. Colleen Keltz is the Communications Manager for the Water Quality Program with the Washington Department of Ecology.

Increasing spill over dams leads to an increase in gases in the water, mainly nitrogen and oxygen. There is a water quality standard for this, called Total Dissolved Gas, and Ecology is proposing to change the amount of gases allowed in the water for the Snake and Columbia rivers. Spilling more water at specific times could allow more juvenile salmon to make it to the ocean, eventually leading to more prey for orca and more adult salmon returning to spawn. However, there is a risk with increasing the amount of gases, as it can harm aquatic life through a condition called ‘gas bubble trauma’. The proposed changes aim to minimize the potential negative effects, while improving salmon passage and survival. The comment period ends September 26th. More information can be found on the department of Ecology’s website.