DEMING - The warmer, drier summers that will result from climate change could be the final straw for diminishing salmon populations in the south fork of the Nooksack River, according to officials developing a report on what needs to be done to keep the stream habitable.
The south fork already is too warm in the summer for growing or spawning salmon, according to the state Department of Ecology. Since 2001, the preferred way to give salmon some cool respite in the south fork has been to place artificial logjams in the stream. That is relatively inexpensive; some 100 logjams have been installed at a cost of about $7 million, said Oliver Grah, water resources program manager for the Nooksack Indian Tribe.
Other, more expensive projects will be needed if threatened species such as the spring chinook are to overcome the additional threat posed by climate change, officials said.
"(Climate change) is great news for people who like warm weather to float in the tubes, but fish are going to need places to get out of that (warm) water," said Steve Hood, water quality engineer in Ecology's Bellingham office.
Some 150,000 coho, steelhead and chinook were caught in the Nooksack River in 1895. Since then, the numbers of salmon-type fish, including certain trout species, have declined more than 90 percent. Chinook, steelhead and bull trout are listed as "sensitive" or "threatened" under the federal Endangered Species Act.
Chinook are especially significant to the Nooksack tribe for its economy and traditions and for family subsistence, Grah said.
Development, not climate change, devastated the salmon stocks. Grah pointed to a number of culprits: timber cutting, farming, paving, and flood control that kept the river out of its natural floodplain.
Climate change's impact might be lighter than the hit fish have taken from development, but increasing temperatures could be "the straw that breaks the camel's back," Grah said.
The south fork will flow warmer in the future climate because of warmer air temperatures and lower water flows in the summer. Fall storms are expected to be more intense, which could scour away salmon eggs.
Grah is working with Steve Klein at the Environmental Protection Agency on a pilot project to incorporate climate change into an otherwise standard report from Ecology on the temperature problem in the south fork. If the pilot project is successful, it will be a model for how agencies incorporate climate change into the traditional pollution studies, Klein said.
"There's just a handful of places out there that have tried to address (climate change)," he said.
Final reports by Ecology and the EPA aren't due until next year, but officials have a good idea of what will be needed to help the south fork salmon. Those projects in some cases will be more expensive. In every case, they will take a lot of time, Grah said.
To keep temperatures down, more trees should be planted along the riverside. Also, levees or other barriers should be removed or set back to allow the river to slow down and spread over its natural floodplain after storms. Sediment carried into the river from unstable slopes created by development should be better managed, too, Grah said.
If including climate change in Ecology's temperature study of the south fork adds anything, Hood said, it's a sense of urgency.
"Over the next 40 years the stream's going to get a lot warmer," he said. "If we're growing shade at the same rate as the temperature is warming up, we can conceive of things not getting worse as the climate warms. This will give fish more time to adapt."
-- Read a preliminary report by the Department on Ecology on the south fork Nooksack River study by searching the web for "Ecology publications 1203126"
-- Information on the EPA's climate change pilot project can be found at epa.gov by entering "south fork Nooksack" in the search box.
Reach RALPH SCHWARTZ at firstname.lastname@example.org or call 715-2298.