For a riverbed so dry that salmon could not reach it and young cottonwood trees were dying of thirst, there sure were a lot of mosquitos. They swarmed over every patch of bare skin as Jeff Mount and Mike Eaton walked a section of the dessicated Cosumnes River last week.

But the bugs did not suck any of the joy out of the morning because this was a day Mount and Eaton had worked toward for 10 years — the day when water would be restored to the dry Cosumnes.

"Salmon are sitting at the base of this river right now," said Mount, director of the UC Davis Center for Watershed Sciences. "The number of wild salmon on this river has plummeted to near zero simply because it's too dry."

"Rewatering" the river, said Mount and Eaton, a senior project director for The Nature Conservancy, was the result of efforts by many people in the university, conservation, government and farming communities.

It is this type of project that is envisioned for the campus's new $5 million Watershed Sciences Building. On Wednesday, the university held a grand opening for the facility at 425 South La Rue Road. The center is dedicated to the study of watershed science, with a focus on the sustainable restoration and management of Northern California stream, lake and estuarine ecosystems — such as the Cosumnes River project.

To this end, groundwater expert Graham Fogg was particularly key to figuring out why the Cosumnes was dry and what might be done about it.

Fogg and graduate student Jan Fleckenstein had determined that although the river often has some dry sections in summer, a half-century of groundwater pumping within the Cosumnes watershed was making those dry sections bigger (up to 20 miles long) and longer-lasting.

As a result, the scientists found that fall-run Chinook salmon could not travel upstream to spawn and young trees in the riparian forest could not survive. (Fleckenstein is now an assistant professor of hydrology at the University of Bayreuth in Germany.)

Eaton used the UC Davis research findings to forge an agreement with water agencies in Sacramento County to release up to 5,000 acre-feet of water into the river. For the project to succeed, the new surface water must recharge the aquifer by saturating the ground beneath the Cosumnes River bed. Once the ground is saturated, natural rainfall and runoff will remain in the river channel instead of seeping into the aquifer.

Said Eaton, "From a conservervationist's perspective, this is momentous. It addresses a real insidious problem that's been going on for decades and it really represents a lot of collegial thinking and consensus about how to manage this problem."

The Center for Watershed Sciences will conduct follow-up studies to determine if the timing and amount of water recharge are correct. On Oct. 17, Eaton and Mount were all smiles as they waited at one of the river's surviving wet spots for the first reviving injection of water to arrive.

"Sometimes when you do university research you figure you'll never see it come to fruition," Mount mused. "It's heartening to have basic research result in a bona fide application."

Then a rush of frothy water tumbled from a pipe into the Cosumnes. Little fish zoomed toward the waterfall and hawks that had been invisible before began screeching from nearby trees and flew over to investigate.

"Woo-hoo!" exulted Mount. "Every-thing comes to life."