Uvas Creek - Ecology

Ecology

Uvas Creek supports a self-sustaining population of steelhead that is part of the Southern Central California Coast Distinct population segment (DPS), which is listed as “threatened” under the Endangered Species Act. The year before Uvas Creek Dam was constructed in 1957, the Santa Clara Valley Water District (SCVWD) agreed with the California Department of Fish and Game (CDFG) in a Memorandum of Agreement (MOU) to maintain flows sufficient to protect Steelhead trout (Oncorhynchus mykiss) populations below Uvas Reservoir and to collect and truck returning adults above the dam to spawn upstream, however this latter promise was not kept.

A non-profit volunteer organization called CHEER (Coastal Habitat Education and Environmental Restoration) founded by Herman Garcia, transports steelhead stranded in drying pools to reaches of Uvas Creek that are perennial. In 2008, Garcia's organization transported more than 23,000 steelhead, a dramatic number compared to the 100-200 fish reported in the entire Pajaro River system in 1991. Two tributaries of Uvas Creek are also steelhead spawning and rearing streams, Bodfish and Little Arthur Creeks.

The northwest to southeast orientation of Uvas Reservoir is in line with prevailing winds which drive the warm surface layer (epilimnion) down into the cool bottom layer (hypolimnion), so that by late summer the bottom water is warm and anoxic. The result is that no wild or planted trout survive the summer in the reservoir. Landlocked steelhead above Uvas Dam take the rainbow trout form, and genetic studies of these fish in upper Uvas Creek above Uvas Road show that they are of native, and not hatchery stock.

Other native fish species in the Uvas Creek watershed include Sacramento sucker (Catostomus occidentalis), Sacramento pikeminnow (Ptychocheilus grandis), California roach (Lavinia symmetricus), Riffle sculpin (Cottus gulosus), Pacific lamprey (Lampetra tridentata), and Threespine stickleback (Gasterosteus aculeatus). Prickly sculpin (Cottus asper) and Hitch (Lavinia exilicauda) are also present, but are relatively scarce. Non-native fish are uncommon in Uvas Creek.