The West Fork San Gabriel River is located in the San Gabriel Mountains of Los Angeles County. The West Fork is a highly productive stream that can be fished all year. The only trout species found in the river are rainbow trout .
Fishing can be great in the winter, as well as providing a cool refuge from the heat in the valley.
At certain times of the year, sediment-laden releases from the reservoir cause muddy stream conditions. The West Fork San Gabriel is important because it supports native nongame fishes as well, including the arroyo chub, speckled dace, and the Santa Ana sucker, recently listed as threatened under the Endangered Species Act.