Aly Lie ( Aquatic Ecotechnologies)

Photo by Dawnmarie Fehr

Aly Lie, with Aquatic Ecotechnologies, takes a sample of the water from the Delta in Discovery Bay. The test samples are designed to help find ways to mitigate the blue-green algae.


Scientists have begun a load study in the Discovery Bay Delta to find out if hydrogen peroxide will help mitigate harmful algae blooms.

The experiment is a collaboration between the Regional Water Quality Control Board, Aquatic Ecotechnologies and the Discovery Bay Community Foundation (DBCF). Funded by a grant of $80,000, the project began on Aug. 25 and will conclude on Sept. 8.

“We are trying to knock down the blue-green algae (BGA),” said the project’s lead scientist David Caron. “There are thousands of other types of algae, and we are expecting that once we knock these (BGA) down with the treatment, that other good algae — algae that are beneficial to the food chain — will grow up in their place.”

BGA is also known as cyanobacteria, and in high quantities can be dangerous, even deadly, to humans and their pets.

Caron hopes that giving the good algae a competitive edge will allow the Delta aquatic community to return to normal. To conduct the experiment, 12 large plastic tanks were placed in one of Discovery Bay’s bays and secured to a dock. The water in each barrel was treated with varying concentrations of hydrogen peroxide, which Caron hopes will kill the algae, decreasing the dangerous blooms to a safe level. Once final samples are collected, it will take Caron’s company, Aquatic Ecotechnologies, several months to analyze the data.

Caron explained that hydrogen peroxide, while detrimental to BGA, does not harm other types of algae, making it an ideal choice to mitigate the cyanobacteria.

“We are testing different concentrations in order to find a concentration that would be optimal for killing or holding down the cyanobacteria but not affecting the rest of the community,” said Caron. “In our measurements, we are not measuring the effect on fish because the tanks aren’t big enough, but we are measuring other components of the plankton community to make sure they aren’t also detrimentally affected by the addition of the hydrogen peroxide.”

He noted if the experiment is successful, the lowest concentration of hydrogen peroxide would be used, as it would be both safer and cheaper. The concentrations they are using are far less than the 3% hydrogen peroxide available in stores. Pouring that into the water would do little to no good against BGA and could be harmful to humans and wildlife.

Meredith Howard, environmental program manager for the Central Valley Regional Water Board, said Discovery Bay is the perfect spot for this cutting-edge experiment.

“What Dave has put together here is a really nice experiment to figure out if we can use something that is not a harsh algicide, per se, that will dissolve in the environment and kill the biomass and — we are hoping — also absorb or degrade the toxins,” Howard said. “Discovery Bay is an area where we know we have annual cyanobacteria blooms every year. We know toxins are produced by the cyanobacteria. And the last few years, we have been out here, and toxins are detected every year.”

She noted successful results will lead to potential solutions in other parts of the Delta and even bodies of water around the world, as BGA is a global issue.

BGA grow in warm, nutrient-rich water and prefer stagnant or shallow water. It can collect in large quantities that look like blue, green or brown scum floating on the surface or suspended in the water. Buildup usually starts attracting attention in late summer then dissipates as temperatures cool and rain washes out the water.

Contra Costa County did find dangerous levels of cyanobacteria in samples collected on June 4 of this year. Since then, warning signs have been posted at the Discovery Bay Marina. The BGA will not grow in fast moving water but tend to cling to the edges of bays, frustrating those who want to swim off their docks.

Some residents did take issue with the county’s samples, as they were gathered right next to docks, rather than in the middle of the bays. The residents felt the samples did not paint an accurate picture of the water, as algae along the rocky edges of the town’s bays is able to survive almost year-round.

“It’s unfortunate these samples were taken next to the levee where the scum collects, instead of a minimum of 100 feet away from the docks where it is a better representation of the water quality in the bays,” DBCF president Jim Mattison said.

Mattison also theorized the algae will continue to worsen until the state regulates the amount of nitrates, phosphates and other toxins washed into the Delta by local farmers. He noted those chemicals feed the BGA.

Mattison has been working with the county, state water boards, local representatives and various water-safety committees to look for a solution to the cyanobacteria. He and his foundation were instrumental in applying for the grant and donating time to take county officials on the water.

“Our initial results seem encouraging,” Mattison said of the experiment. “But everything has to be approved by several different federal and state entities, and then there is the cost of treating our 800 acres of water in Discovery Bay and getting the funding. It’s an uphill battle, but we will continue to push forward for our community.”

In the end, BGA has been in Discovery Bay for a long time and will likely not be eliminated.

“This all comes under mitigation,” Caron said. “This doesn’t solve the problem of the nutrients that are causing the growth. It will possibly be a short-term mitigation approach. When you have material like this and its very toxic, there may be a mitigative strategy you can use to lessen it.”