In previous experiments at Stinson Beach, Boehm and her colleagues recorded a spike in phytoplankton following a period of nitrogen-rich groundwater discharge. And in subsequent laboratory experiments, Stinson Beach groundwater proved to be a good meal for algae.
"In the lab, we induced small phytoplankton blooms in ocean water by adding just a little bit of fresh groundwater from this site," de Sieyes explained. "In communities like Stinson Beach, whatever doesn't get treated in the beach is ultimately going to flow into the ocean," de Sieyes said.
Fixing the plumbing
Many California communities have switched to conventional sewer systems as an alternative for treating wastewater. But septic-to-sewer conversions are pricey and encourage development, Boehm said. Wastewater plants are also energy hogs, de Sieyes added.
"Because septic systems rely on naturally occurring bacteria in the ground to do the cleaning, they're much more energy efficient," he said.
But septic system technology hasn't evolved much since the 1950s, Boehm added, so new systems may have to be designed to treat wastewater to a higher degree before it is discharged to a leach field
"If there was a better, cheaper, more efficient onsite treatment technology, I'm sure the Stinson Beach community would be interested in it," de Sieyes said.
In addition to the National Park Service, the research team has presented its findings at public meetings and worked closely with the Stinson Beach County Water District. Even before the study began, the water district had taken big steps to green its shores, de Sieyes said, establishing eco-friendly rules for installing new septic systems, including restrictions on how close to shore they can be built.
"The local water district and the community as a whole deserve a great deal of credit for tackling this issue head-on," he said.
"Our results will provide valuable ins
|Contact: Mark Shwartz|