Scientists brave wet and cold to monitor wetlands health

By Carley Sweet
Information and Education Assistant
Sacramento Fish and Wildlife Office

It was a chilly November morning when John Henderson, Steve Detwiler, Cathy Johnson, and Collin Eagles-Smith from the Sacramento Fish and Wildlife Office’s Environmental Contaminants division began their journey to the North Grasslands Wildlife Area and the San Luis National Wildlife Refuge.

Despite the cold and the possibility of rain, trip leader Henderson was not discouraged.

“This is the nicest time of the year to go,” he said. “When we go down in the summer, the weather is extremely hot and miserable. In the middle of winter, we are comfortably cold.”

And so the slough-bound journey began. With a truck packed full of seining nets, sampling tools, waders, and a portable freezer, the crew headed to the wetlands of the San Joaquin Valley in hopes of gathering enough samples for an ongoing multi-agency monitoring program.

As part of the Grasslands Bypass Monitoring Project, the crew’s work involves collecting samples of the water, vegetation, and aquatic species so they can be tested for the presence of selenium and other contaminants.

Selenium can wreak havoc on a wetland, as demonstrated by the shorebird death and deformities discovered in San Joaquin Valley wildlife refuges in the 1980s. Small amounts of selenium can promote health in plants and animals. But when high doses are ingested, the results can be devastating.

At the time, testing by the U.S. Fish and Wildlife Service confirmed that agricultural drainwater flowing into the wetlands was the source of the selenium. Today, as the region’s farmers work with State and Federal agencies to reduce their selenium discharges, the Service continues to closely monitor sloughs and wetlands. The crew from the Environmental Contaminants program visits the area four times a year.

It is their challenging duty to wade into the murky, muddy depths of these water channels, partnering up to drag hand-held seining nets (large fishing nets with weights at the lower edge and floats at the top) against the chest-high current. For those who prefer to work more independently, a labored walk along the bank’s edge and through the islands of cattail clusters offers the opportunity to use the easily-maneuverable dip-nets.

The tough part of the job really begins after the samples are collected. Seemingly endless hours are spent bent over the sampling station, sorting species by age and sex. Although a variety of species were gathered (mosquitofish, silversides, fathead minnows, red shiners, a few crayfish and small sunfish), the crew's attempt to net the crafty carp was unsuccessful.

After the samples are sorted, they are sent to a lab to be tested for selenium and boron.

Since the beginning of the Grasslands Bypass Monitoring Project, the testing has shown that selenium levels in some areas have declined and stabilized, while in others it is still a problem. Goals and incentives have been established to encourage growers to continue to reduce the selenium load in their agricultural drainage water to meet water quality objectives for the San Joaquin River and tributary channels.

The duck clubs and wildlife refuges in the vicinity of the Project provide some of the best wildlife viewing and hunting areas in the Central Valley of California. Refuge wetlands are essential areas for migrating waterfowl and shorebirds to breed and live during the winter months. It is important that the Grasslands area continues to be monitored for contaminants to ensure healthy wetland ecosystems and protect human health.

Other agencies involved in the Grasslands Bypass Monitoring Project:

U.S. Bureau of Reclamation
http://www.usbr.gov/mp/grassland/

U.S. Environmental Protection Agency
http://www.epa.gov/region9/

U.S. Geological Survey
http://ca.water.usgs.gov/

Central Valley Regional Water Quality Control Board
http://www.swrcb.ca.gov/rwqcb5/

California Department of Fish and Game
http://www.dfg.ca.gov/

San Luis & Delta-Mendota Water Authority
http://www.sldmwa.org/

If you would like to learn more about the Grasslands Bypass Project please visit: http://www.sfei.org/grassland/reports/gbppdfs.htm

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Collection site at Mud Slough, site D on the San Luis Wildlife Refuge

John and Collin start to drag the seine through the slough, while Cathy helps from the bank.
(Site D, Mud Slough)

Todd Williams (San Luis Refuge) and Collin start the grueling process of sorting through the vegetation to look for certain fish species.

Steve dumps his collected samples into a temporary holding bucket
(Site I2, Mud Slough )

John, Collin, and Cathy sort through various aquatic samples.

John and Collin maneuver the seine against the wearisome current.
(Site F, Salt Slough)

Cathy checks her dip-net after trolling along the slough's edge.
(Site D, Mud Slough)