Santa Cruz County streams are home to a wide variety of native fish and wildlife. Our local streams support steelhead, Pacific lamprey, Sacramento sucker, riffle sculpin, three-spine stickleback, and California roach. Santa Cruz County streams also support other sensitive wildlife species such as the California red-legged frog, foothill yellow-legged frog, and western pond turtle.
The functioning of the stream ecosystem and the distribution of aquatic organisms within the stream is regulated by the various interrelated physical and chemical parameters of the stream environment: current velocity, substrate, chemical quality, temperature and light availability, among others. Maintenance of adequate streamflow, water quality, bottom conditions, and overall health of the stream ecosystem is essential for maintenance of steelhead and coho salmon resources. Also, the health of the stream's biotic community is an indicator of the health of the watershed as a whole and can affect the quality of the water for other beneficial uses such as water supply and recreation.
Substantial declines in fish populations in Santa Cruz County have resulted from the reduction of habitat by excessive sedimentation and streamflow reductions from direct diversion and groundwater withdrawal, among other stressors. Instream flow requirements for fish, other aquatic biota and riparian vegetation varies with each season, stream and from reach to reach on the same stream. The amount of streamflow necessary for optimal salmon and steelhead production is also greatly influenced by streambed conditions.