Valley Water increases flows into Coyote Creek to encourage threatened steelhead trout to migrate to San Francisco Bay

People walking along the Coyote Creek trail this month might notice an increased flow of water in the creek.

The increase is not the result of a late spring storm. Valley Water has opened the radial gates at the small dam that impounds water in Coyote Percolation Pond (also known as Metcalf Pond) just north of Metcalf Road in South San Jose to benefit the threatened steelhead trout population in Coyote Creek.

Valley Water manages Coyote Creek and the Coyote Percolation Pond to recharge the groundwater aquifers. As part of our core three-pronged mission, Valley Water also strives for a healthy ecosystem along the creek.

Under that environmental stewardship mission, Valley Water coordinates its activities in rivers and creeks within Santa Clara County with fisheries agencies such as the California Department of Fish and Wildlife (CDFW) and the National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries.

Valley Water has coordinated with NMFS and CDFW a spring pulse flow in Coyote Creek.  A pulse-type flow in a managed stream is a sharp, sudden increase in flow of water for a relatively short period of time and then a decrease back to the original flow. The objective of the spring pulse flow in Coyote Creek is to give steelhead, a federally threatened species, a signal to migrate downstream to the San Francisco Bay.

By doing so, the steelhead will have a better chance at thriving and growing, especially after Oct. 1, 2020, when Valley Water starts to drain Anderson Reservoir. Valley Water will empty Anderson Dam per the order by the Federal Energy Regulatory Commission that was issued on Feb. 20.

“As we prepare to drawdown Anderson Reservoir, our agency is working closely with the state and federal resource agencies to ensure that we take every appropriate action to minimize harmful impacts to fish, wildlife, and the environment,” said Nai Hsueh, Chair of the Valley Water Board of Directors. “The goal of releasing additional water into Coyote Creek at this time is to benefit the threatened steelhead population.”

Between May 6-10, Valley Water drained the Coyote Percolation Pond in advance of the pulse flow and residents might notice downstream fluctuation of flow. The Santa Clara County Parks and Recreation Department and the City of San Jose have been notified by Valley Water of the increased creek flows. The City of San Jose notified residents via social media, as well as the unhoused/unsheltered population along the creek.

Community members who use a trail along Coyote Creek might see a flooded spot along the trail that is in a low-lying area. Please use caution while walking, running or biking along the trail.

On the evening of May 11, additional water was released from Anderson Reservoir at a rate of 120 cubic feet per second (cfs). One cubic foot per second is the equivalent of 448 gallons of water per minute. On average, about 40 cfs is released into Coyote Creek throughout the year.

The following day, the flow will be dropped to 90 cfs, and then 60 cfs for the subsequent three days to encourage steelhead to out-migrate. Gradually decreasing the pulse flow is expected to give the steelhead a signal to move downstream, according to biologists from Valley Water and NMFS.

Towards the end of the week of May 11, Valley Water staff will start refilling the Coyote Percolation Pond, which is an important recharge facility for the Santa Clara Sub basin. After that, flows will soon resume to normal for this time of year.

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