Eradication of northern pike in Lake Davis completed normal lake levels to return

Residents in Plumas County will soon see Lake Davis and its reservoir returning to normal operations after more than two decades of efforts to eradicate invasive northern pike.

The state Department of Water Resources (DWR) lowered Lake Davis in the 1990s to prevent water from spilling into downstream waterways thereby spreading the predatory pike. DWR further attempted to prevent spills by use of a “strainer” at the base of the dam.

The non-native northern pike were initially found in Lake Davis in 1994. The Department of Fish and Game (now Fish and Wildlife) initially attempted to eradicate the pike through use of the chemical treatment rotenone but the predators were rediscovered in the reservoir in 1999. A second treatment of rotenone in 2007 was successful; the effort was aided by the reduced water levels in the lake.

The reduced water during the years was two-fold. In addition to preventing water spills in to the downstream channels – and thereby containing the northern pike – the reduced water was an effort to protect the native fish species. DWR has kept the reservoir level well below the dam’s rim.

Part of the DWR’s Upper Feather River Project, Lake Davis has continued to provide drinking water to the residents of Portola in spite of the lowered water levels. The lake is a popular recreation area within the Plumas National Forest. The reservoir is created by Grizzly Valley Dam on Big Grizzly Creek, a tributary of the middle fork of the Feather River. The 84,000-acre-foot reservoir provides recreational camping, fishing, picnicking and boating.

Northern pike are ambush predators that use their coloration and surrounding aquatic vegetation to hide and swiftly snatch prey that passes by. Northern pike can tolerate a wide range of environmental factors, including warm and cold temperatures, brackish waters (low-salinity), and low oxygen levels. Their diet consists mainly of fish, but they will also eat frogs, snakes, small mammals, and birds if given the opportunity. In areas were northern pike have been introduced, they have altered fish community composition and reduced fish species diversity (including eliminating native species) through predation and competition. If northern pike were to become established in California, they would pose a serious threat to many native fish species populations, including salmon, trout and other species.

The Department of Water Resources announced that with the eradication of the northern pike from Lake Davis normal operations at the reservoir will resume and the reservoir will now be allowed to fill. The strainer structure at the base of the dam has not been operational for years and is now causing operational difficulties. DWR now plans to dismantle the device.