| Introduction | Creek Description | Procedure | Species present | Results | Discussion |

Rotenone Treatment

In an effort to reverse the decline of anadromous salmonids in Big Chico Creek, the California Department of Fish and Game (DFG) undertook on October 6, 1986, to remove fish from the middle zone of the creek (Map). The piscicide rotenone was applied from a drip station to produce a calculated instream concentration of 1.07 ppm of commercial rotenone formulation (26.75 ppb as rotenone). Total drip time was 19 hours, 35 minutes. During this time a crew spot-treated side waters and springs along the treated zone. Instream rotenone concentrations measurd by DFG personnel about 1/3 down the run and at the detox site averaged 16 ppb and 5.1 ppb respectively. At the end of the 16 km treatment stretch, the rotenone was detoxified with potassium permanganate.

The "target area" of Chico Creek extended from the waterfall which forms the upstream limiter for both non-salmonid and anadromous fish, downstream to a washed-out fish ladder near the upper end of Iron Canyon. The "treated area" extended further downstream to a convenient site for detoxification. Treatment was partially justified by the assumption that Iron Canyon, with its non-functional fish ladder would act as a barrier to prevent recolonization of the target area by non-salmonids.

Subsequent to the treatment, excess fry from the Feather River Hatchery were planted at Ponderosa Way to try to re-establish populations. Each spring from 1987 to 1992, 100 to 500 thousand spring-run chinook salmon fry were planted. In years 1987, 1988, and 1990 from 50 to 100 thousand steelhead fry were planted.