WEITCHPEC, Calif. — For thousands of years, the Klamath River has been a source of nourishment for the Northern California tribes that live on its banks. Its fish fed dozens of Indian villages along its winding path, and its waters cleansed their spirits, as promised in their creation stories.

But now a crisis of opioid addiction is gripping this remote region. At the same time, the Klamath’s once-abundant salmon runs have declined to historic lows, the culmination of 100 years of development and dam building along the river.

Today, many members of the Yurok, Karuk and Hoopa tribes living in this densely forested area south of the California-Oregon border see a connection between the river’s struggle and their own.

“It’s no coincidence to me that this opioid problem and the river crisis are happening at the same time; when that resource is gone, it leads to a sense of despair,” said Amy Cordalis, the Yurok tribe’s general counsel.