Treatment planned for algae

Photo courtesy of Darin Ganem

Turtle Bay, located in Discovery Bay west, is one of the areas targeted for algae treatment.

As temperatures warm up and the year creeps closer to summer, many Discovery Bay residents are looking toward the water and wondering what the next current will bring.

Invasive weeds and toxic algae can sometimes temper the beautiful lifestyle many Delta residents love, but local agencies are working to keep the waters clear. Representatives from the Discovery Bay Community Foundation (DBCF) have partnered with the Department of Boating and Waterways (DBW) to mitigate invasive weeds – such as floating hyacinth and egeria densa – clogging some parts of the Delta.

Discovery Bay Community Foundation President Jim Mattison discusses plans for treatment of the Delta water weeds that have infiltrated bays throughout the community.

“We are blessed to have such a great working relationship with the Department of Boating and Waterways, and we’re extremely fortunate they are able to treat our bays every year, as they only have enough funds, manpower and product to treat 65% of the Delta every year,” said DBCF president Jim Mattison. “Much more funding is desperately needed, so they can treat and maintain the entire Delta every year.”

Last year, weed abatement and spraying programs were delayed by shelter-in-place orders issued in March to slow the spread of the COVID-19 pandemic. Due to policy changes and several new COVID-related rules, DBW began treatment in late May, rather than early March. By then, weeds had taken over some of the bays in Discovery Bay West, including Turtle Bay, where Darin Ganem has lived with his family for 12 years. He said when the weeds began causing issues seven years ago, a meeting was held between local stakeholders from the state, county and Reclamation 800 district.

“They’ve been treating (the weeds) every year since that meeting,” Ganem said. “Last year was an exception because of COVID. They started later, and the weeds didn’t die until August or September, and by then, summer was over.”

This year, DBW will begin the first of three planned treatments for the weeds after March 19. Mattison noted one of the challenges for DBW lies in the fact the Delta is surrounded by 8,000 acres of agriculture in the Brentwood and Knightsen area, sharing water running from Kellogg Creek. Since this water is used for agriculture, lower amounts of treatment chemicals, like Fluridone pellets, are required.

Mattison said a solution has been found in a new product for killing the weeds called Diquat.

“We were first given permission to use and experiment with Diquat in 2018 in a couple of bays along Kellogg Creek,” he said. “With great results and no harm to aquatic life, the DBW was granted permission from Fish and Wildlife to be able to use Diquat in a few more bays in 2020, and now in 2021, will be using Diquat in all the bays west of Discovery Bay Boulevard.”

Another concern for some residents is the blue-green algae that grows in still corners of Discovery Bay once summer heat has settled in. After the drought of 2011 to 2015, the amount of algae seen each year increased due to lower water flows. The algae feed on excess nutrients from fertilizers washed into the Delta and release cyanobacteria when they bloom.

“The higher concentrations of these nutrients cause increased growth of algae and other aquatic plants,” Mattison said. “As a result, the more algae that grows, aquatic life and other forms of life begin to die. There are over 500,000 acres of farmland in the Central Valley, all using some form of fertilizer.”

Mattison and the DBCF have been working with a committee made up of water board members and scientists to study the algae and find ways to mitigate it. He has facilitated monthly water samples throughout the 32 bays of Discovery Bay. With the Central Valley Water Board, the foundation received an $80,000 grant to conduct research on ways to reduce cyanotoxins in the Delta.

“We invited a team of scientists to set up experimental stations in Windward Bay, where blue-green algae was extremely abundant,” Mattison explained. “Using a hydrogen peroxide-based formula, we were able to see how much was used to kill the bad algae and keep the good algae.”

More testing is needed to find a solution, and the team will continue to work to secure funding and conduct research on a problem that is more pervasive across the country each year. In Discovery Bay, most bays built 50 to 60 years ago have little circulation beyond tidal flow.

“Unfortunately, we now have to play the cards we were dealt,” said Mattison. “Rest assured, we are working hard with many entities to keep our bays as useful as possible. I know it gets frustrating as I field a lot of those calls during the summer, but we are working directly with the big dogs and know they are getting tugged at by everyone else.”

Treatment days and bays will be updated on every two weeks. For specific questions on aquatic weeds or blue-green algae, contact Mattison at