Researchers wade near wetlands to
collect water quality samples.

Newsletter - Spring 2008

Current Research - Environmental Quality

Constructed wetlands for water quality mitigation?

Cooperative Extension Specialist Toby O’Geen is interested in the constructed wetlands of the central valley. He and his crew of two graduate students, four undergrads, two staff members and one post doctoral scholar are evaluating the ability of the wetlands to improve water quality.

The wetlands receive tail water from adjacent farms. The idea is that the wetlands can function as a filtration system to keep the San Joaquin River clean.  Traditionally, farmers pump water from the river through canals and run it through their fields before returning it to the river. Can these constructed wetlands, originally built for duck habitat, improve water quality?

O’Geen is trying to find out. He has been taking samples from input and output locations of the wetlands.

So far, findings indicate that the wetlands are most effective in removing suspended sentiment (i.e. eroded soil), with 85-95% of it removed. He also found that the wetlands remove contaminants such as phosphorous and nitrate nitrogen. O’Geen is now looking into the removal of pathogens and pesticides, which he says looks promising.

“Preliminary information indicates the wetlands have potential to be a valuable best management practice for irrigated agriculture,” O’Geen explains. “These constructed wetlands can help mitigate both point source and non point source pollution.”