Santa Ana River Wash

View looking northwest across the Santa Ana River Wash from the vicinity of Opal Avenue.

Researchers are finding that there are environmental consequences to regulating the flow of the Santa Ana River.

“As water agencies increasingly make the river more controlled, it disrupts the natural scouring and rejuvenation of habitat that takes place in the river with flood events," said Heather Dyer, a fish biologist and senior water resources manager with San Bernardino Valley Municipal Water District (Valley District).

“Native species depend on periodic scouring of the historic flood plain, including the lateral scouring of channels and other disturbances that remove fine sediments and grasses. We have to figure out how to better manage habitat in the entire flood plain so that the species we’re trying to protect can continue to thrive.”

Water agencies learned about this and other research findings recently during the second annual Santa Ana River Science Symposium held on Oct. 22 at UC Riverside. The daylong event, co-sponsored by Valley District, ICF International and Stillwater Sciences, included 22 speakers.

They focused on four main topic areas, including the Santa Ana River High Flow Study, alluvial fan biology, Santa Ana River biology, and Santa Ana sucker biology and restoration.

Valley District and other water agencies have a vested interest in maintaining the ecosystem health of the Santa Ana River. The agencies must successfully manage and protect habitat for threatened and endangered species in order to obtain the permits they need from state and federal environmental protection agencies to build additional water capture and groundwater recharge facilities.

Valley District and its 11 partner agencies are close to finalizing the Upper Santa Ana River Habitat Conservation Plan, which creates a roadmap for protection of endangered species and the timely approval of water infrastructure projects. The plan is expected to be released for public comment in December.

Dyer is a fish biologist who spent five years working for the U.S. Fish and Wildlife Service before joining Valley District in 2014 to help coordinate the water agency’s habitat restoration and protection efforts with wildlife protection agencies.

“It’s actually possible to have a healthy, functional and resilient urban river that provides water supply and supports native species if you are willing to collaborate with a diverse set of stakeholders and invest in the science to find win-win solutions,” Dyer said.

The Santa Ana River provides roughly 75 percent of the water supply for the San Bernardino Valley. Valley District supplements this supply by importing State Water Project water from Northern California, which it supplies to water agencies across the San Bernardino Valley, from Rialto to Yucaipa, including East Valley Water District, which serves Highland.

Planning is already underway for next year’s Santa Ana River Science Symposium, which will include not only research focused on habitat topics involving the river in San Bernardino, but additional research by scientists who are studying habitat issues along the river as it makes its way across Orange and Los Angeles counties. She said such research will help water agencies across Southern California as they grapple with ways to improve management of habitat for threatened and endangered species.

Valley District hopes to eventually establish a single, searchable online database at UC where all of the latest research involving the Santa Ana River could be stored. The district is applying for grants to help cover the cost of the database.

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