After decades of debate and legal challenges, California’s Department of Fish and Wildlife is poised to poison a creek in order to save the endangered trout that have lived there for thousands of years.

Biologists will dump poison in an 11-mile stretch of Silver King Creek south of Lake Tahoe in an effort to kill off invasive hybrid trout that helped land the Paiute cutthroat trout on the federal Endangered Species List in 1967. The plan has been hotly contested and was the subject of three lawsuits.

Fishing enthusiasts support the plan and environmental groups have tended to oppose it. A U.S. District judge removed the last barrier to executing the plan in May when he dissolved a 2011 injunction (pdf) against it.

The non-hybrid trout, which exists exclusively in the Silver King Creek and other isolated tributaries in Alpine County, were nearly extinct by the 1970s after the introduction of rainbow trout and other cutthroat trout in preceding years caused hybridization of much of the stock. Sheepherding and cattle raising in the area added habitat degradation to the mix and by 1985, the fate of one of the world’s rarest trout was looking grim.

The U.S. Forest Service put together a recovery plan (pdf) that met stiff resistance from some environmental groups who objected to what they considered overkill. “They’re going to destroy an area and kill all the fish, and they think it’s a great idea,” Laurel Ames of Friends of Silver King Creek told the Reno Gazette-Journal. “It just simply doesn’t make sense.”

But she acknowledged, “You can only do three lawsuits, then you have to let it go.” A federal judge in May cleared the way for the  

As many Paiute cutthroats as possible will be electro-shocked and removed from the river for transport to a safe haven downstream. The poison rotenone will then be used to kill all the fish left in that stretch of the river and, in the process, also kill all the native invertebrates. Another treatment will be applied next year and perhaps another year after that.

Then the relocated Paiute cutthroats and others from a hatchery will be reintroduced to the river. A similar restoration plan was successfully executed in the creek above the natural barrier of the Llewellyn Falls to the north between 1986 and 1993.  

Rotenone is a piscicide that suffocates gill breathers. It has been banned in the United States for use on land, coastal waters and lagoons. It has been banned entirely in Europe. But in this country, it is allowed to be used in freshwater lakes and streams, to the consternation of many wilderness users and scientists.

–Ken Broder

To Learn More:

Push to Restore Rare Trout Involves Poisoning Sierra Creek (by Jeff DeLong, Reno Gazette-Journal)

Agencies to Move Forward with Trout Restoration (by Dylan Silver, Tahoe Daily Tribune)

California Biologists Poisoning Creek to Save Fish (Associated Press)

Paiute Cutthroat Trout: Restoration Project (California Department of Fish and Wildlife)

Californians for Alternatives to Toxics, et al v. U.S. Fish and Wildlife Service (U.S. District Court for the Eastern District of California) (pdf)