The Lake Shastina on the Shasta River, on Tuesday September 1, 2009, near Yreka, Calif., with water levels at all-time lows, the Southern end of the lake is nothing more than drying mud puddles. Photo: Michael Macor / The Chronicle

By Peter Fimrite, Chronicle Staff Writer The key spawning grounds for what was once the greatest run of salmon on the North Coast are close to being as dry as they have ever been, according to biologists and the U.S. Geological Survey. As California bakes under a third year of drought, the Scott and Shasta rivers, near the California-Oregon border, have become little more than dry beds of rock and dirt. Recent measurements showed the water volume in both rivers approaching record lows for this time of year. The two tributaries of the Klamath River are historic breeding grounds for salmon and are considered critical to the recovery of the species. “Large areas of the (Scott) River have gone completely dry, stranding endangered coho salmon as well as chinook and steelhead in shallow, disconnected pools of water,” said Greg King, president of the nonprofit Siskiyou Land Conservancy, which has fought to protect the salmon runs in the Klamath River system. “This could be the year that causes the coho to go extinct if they can’t get upstream in the Scott and Shasta.” …

Key salmon spawning rivers all but dry