Spill begins for juvenile Snake River steelhead

LOWER GRANITE DAM - An annual water spill began on the Snake River to aid juvenile steelhead and salmon migration to the Pacific Ocean.

The spill operation began April 3 on the lower Snake River dams.

The purpose of the juvenile fish passage is to reduce the number that passes through turbines and cut down on passage delay at the dams. Fish travel time through the Snake River is reduced.

Specific "Flex Spill" operations at the dam are put in place by the U.S. Army Corps of Engineers.

Spilling for 2021 will again include juvenile fish passage spills for eight hours each day during times of higher energy demand and higher electricity prices. For the other 16 hours per day, when electricity prices are lower, the spill will go up to the maximum allowed by state water quality standards.

"The continued trial of flex spill will help us assess both short and longer-term benefits to fish while also providing flexibility to balance clean power generation with the needs of fish as we operate the system," said Tim Dykstra, senior fish program manager for the USACE's Northwestern Division.

The success of spill operations will be determined in two to five years when the juvenile fish that migrated downstream return as adults. Some have projected higher adult returns as a result of the increased juvenile passage.

"We need to keep asking the question, 'How can we do this better?,'" said Michael Tehan, Assistant regional administrator for the Interior Columbia Basin in NOAA Fisheries West Coast Region. "This is an important opportunity to test the projections for what higher spill may do for fish."