PORTLAND — Oregon and federal officials will work over the next three years on plans to locate, protect and restore sections of cold-water habitat for migrating fish in the Columbia and lower Willamette rivers, according to an agreement released Tuesday by NOAA Fisheries.
The agreement is included in an updated plan reviewing Oregon’s standards for water temperature. Known as a biological opinion, the revised plan was ordered by a judge two years ago as part of a settlement with an environmental group that twice challenged the standards in court.
According to the plan, the warmest temperatures allowed under state standards may harm nine fish species unless cold-water zones are implemented. The plan concludes the state has lacked a clear blueprint to map and develop these areas, known by the scientific term refugia, and it proposes a detailed framework to implement the work.
Warm water can kill salmon and other cold-water fish as they migrate upstream to spawn, and drought and climate change have exacerbated the problem. This summer, thousands of sockeye salmon died in the Columbia River because of excessively hot water. On the Willamette, water temperatures that were warmer than usual also killed spring Chinook.
Scientists have found that salmon and steelhead during their migrations seek out cold-water zones when temperatures spike during dry summer months or because of climate change.
Officials say the refugia will act like stepping stones in the rivers, allowing fish to temporarily escape lethally hot waters and make it safely to spawning grounds. “With scientists predicting we may have more of those hot years in future … these refugia are going to play an even more vital role,” NOAA Fisheries senior biologist Jeff Lockwood said.
After Oregon adopted temperature standards in 1996, federal agencies concluded they would not harm endangered and threatened fish species, and the U.S. Environmental Protection Agency approved them. But a legal challenge sent the agencies back to the drawing board.
When the state revised the standards and the EPA in 2004 approved the new ones, the group again sued.
In its newest plan, NOAA found that most of the standards are protective of fish. But it also found that at 68 degrees Fahrenheit, some species in the Columbia and lower Willamette were weak and diseased or died, so they needed refugia to cool off.
To implement the plan, scientists will evaluate temperature-monitoring data, Lockwood said. They’ll document where and how fish use refugia, how many they need and how spaced out they should be.
Although cool water spots already exist, more could be restored, Lockwood said, by reducing temperatures in tributaries, releasing more cold water from dams, reconnecting floodplains or changing forestry and agricultural rules to require buffers of vegetation around streams. Such actions may take years, he said.
