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A Box of Rain

Storm runoff study investigates riparian pesticide management

David L. Brown sets up a flow collector in an orchard in Orland to sample pesticide runoff as part of his research project to evaluate the effectiveness of streamside buffer strips in reducing the amount of pesticide transported from orchards to local creeks.   Adam Radford assists Krissy Gilbert in collecting soil samples for her master’s thesis research, which evaluates the effectiveness of streamside buffer strips in lessening pesticide pollution.

In the midst of this damp and foggy winter, geosciences professor David L. Brown can often be found in a creekside orchard scanning the skies for more rain. Another decent storm would enable him and his team to test the hypothesis upon which hangs his latest research project, the Riparian Buffer Strip Management for Water Quality Control, set up at Lassen Lands almond orchard in northcentral Glenn County.

Will the vegetation planted along Walker Creek reduce the amount of diazinon runoff into the water? And if so, would farmers and orchardists willingly maintain such riparian buffers in order to manage pesticides’ effect on this corner of the planet? Though the swarm of variables surrounding the project and, for that matter, most issues of watershed hydrology would drive the average layperson insane, Brown sees them as a means to two important ends—fostering environmental literacy in students and contributing to good stewardship of the Earth.

Brown, who in 2001 served as Bidwell Environmental Institute’s science director, earned a Ph.D. at University of California, Berkeley. From there, he was hired by the University of Kentucky to direct the teaching and research activities of a 10,000-acre forested watershed. He’s been teaching at CSU, Chico for six years.

“When I came to Chico State, I checked around with people I knew in the environmental industry, and they said Chico State students have a great reputation for hands-on skills,” he recalled.

The project site near Orland, funded through 1996’s Proposition 204 water bond, includes three test plots near the creek. One, serving as the control plot, is simply bare Tehama silt. Another supports the existing weed population, while a third contains purple needle grass, creeping wild rye, California melic, and deergrass—all native vegetation adapted to the dry summers. Stainless steel “flow splitters” have been set up to manage storm runoff and make sample collecting easier. One collector monitors diazinon concentrations in surface runoff, and three others collect runoff samples from the plots. Wells dug either three- or eleven-feet deep monitor shallow saturated zones. A bulk precipitation collector awaits the much-anticipated rainstorm.

“The big thing that vegetation probably does is make the ground more porous,” said Brown. “More water can be absorbed and take the diazinon with it. What you’re doing is slowing the water down to allow the natural biological and chemical reactions a chance to break the material down.

“We sprayed diazinon on the ground as a worst-case example of pesticide loading. Once we finish our setup and the next big rain comes, we’ll know how it works. If we get a good inch of rain, we’ll probably get enough water through our system to see it. The problem is if we get just enough rain to get the water in but not enough to get the water through to the catchment on the other side, we may get only a partial signal. But the way we’re set up, we can go back out in a month, spray again, and try artificial rainfall. We can do a very controlled experiment.”

Along with the Orland project and a full-time teaching load, Brown most recently has helped the Cherokee Watershed Coordinated Resource Management and Plan Group obtain funding, through Proposition 13, for a comprehensive water quality survey of that 95-square-mile area. The watershed includes not only the community of Cherokee but Butte College and Paradise as well. He’s also looking into designs of “virtual tours” for the many desk-bound state regulators in charge of dispersing funds who “don’t know beans about agriculture.” One such tour would demonstrate the seasonal life of an orchard, including water and pollutant runoff.

“There’s a need for these types of projects,” observed Brown, “and the need is something that’s going to make Northern California better—and make the world better, ultimately, but incrementally. Students who want to address this don’t always have to do so through advocacy. There are plenty of advocates out there. There also need to be some solutions.”

Taran March