BELLINGHAM, Wash. — The South Fork of the Nooksack River has become a graveyard for one of the region’s key species: Thousands of Chinook salmon have died because of high temperatures and low water flows since last month, according to a Lummi Nation news release Friday.

Since September, more than 2,500 adult Chinook have died in the South Fork, the release said, and Lummi Nation leaders point to human-caused climate change, habitat destruction and poor management by the state and federal governments as the main drivers.

“We are salmon people and we are devastated by the death of our relatives, the Chinook,” said Lawrence Solomon, chairman of the Lummi Nation, in a statement. “Their deaths resulted from habitat destruction that is made worse by climate change.”

Climate change is causing water temperatures to climb in the Nooksack River, since less snowpack means less cold water flows into the river, according to previous reporting by The Bellingham Herald. Add a reduction in tree cover, which offers shade, and shallower streams in the summer and fall, and you have a recipe for massive salmon die-off.

Water temperatures over a certain threshold stress salmon’s immune system, making them more susceptible to disease, the news release said. The South Fork is designated as temperature-impaired under the federal Clean Water Act, with temperatures consistently exceeding the legal threshold for adult Chinook. The preferred water temperature for Chinook salmon is no higher than 25 degrees Celsius, or 77 degrees Fahrenheit, according to the U.S. Fish and Wildlife Service.

Salmon are incredibly important to the Lummi people, and the Lummi Nation has treaty rights to harvest and co-manage the region’s salmon, according to the tribe’s website.

“Our Schelangen, our way of life, is at risk,” Solomon said in the release.

Without fish to harvest, the treaty rights mean nothing, he said.

“Lummi Nation and other tribes have been working to restore salmon habitat damaged from land development and extraction from logging and agriculture,” Solomon said. “But we need the federal trustees to step up and do more to save and restore salmon habitat.”

Although the dwindling number of salmon has been a concern for decades, continued land development and population growth means little progress has been made, the release said.

There hasn’t been enough political will or funding to address the issue, it said. Washington state itself came to the same conclusion — the 2020 State of Salmon in Watersheds report found that between 2010 and 2019 Washington allocated only about a fifth of the funding necessary to successfully implement habitat elements in regional salmon recovery plans.

“Habitat recovery will take time and be expensive but funding has never been adequate to fix the scale of the problem,” Lummi Nation Chairman Solomon said in the release. “Add to this, the complicated and expensive process for salmon habitat restoration projects at all levels of government, and we are moving at a pace far too slow to stop population declines.”