aquatic weeds

Photo by Dawnmarie Fehr

Weather and the pandemic have delayed the annual aquatic weeds spraying in Discovery Bay and Delta waterways.

Discovery Bay residents are growing irritated with invasive aquatic plants and the COVID-19 pandemic slowing down weed abatement.

While the town can be the ideal place to enjoy a vacation lifestyle year-round, this spring’s crop of weeds is ruining the bays and inhibiting movement around docks on the west side of town.

“The weeds here make boating and watercraft not able to make it in and out of the bay,” said Chris Rossi of Cabrillo Bay. “The weeds get sucked up into the intake, and I even saw a guy stranded in the middle of the bay at one point … the weeds are making the free access to navigable waters somewhat impossible.”

Rossi, who has been in his home since 1998, said the weeds are very bad this year and attributes their growth to the fact the Department of Boating and Waterways (DBW), which treats the weeds annually starting in March, hasn’t sprayed due to the COVID-19 pandemic.

Jim Mattison of the Discovery Bay Community Foundation (DBCF) has been working directly with DBW since 2012 to help ensure the bays on the west side of Discovery Bay, which see more growth than the east side, are maintained and navigable every year. He said the pandemic has held up funding for the chemicals DBW uses to treat the weeds.

“We are still waiting for the liquid Diquat treatments to begin in all five bays along Kellogg Creek, including Kellogg Creek, Lido Bay and Indian Slough,” Mattison said. “We understand what a challenge it has been for getting boats and wave runners out of their docks and into fast water this year, and hopefully, the Department of Boating and Waterways can make a dent in the aquatic weeds in all the bays west of Discovery Bay Boulevard by the middle of June.”

Currently, DBW uses one of two methods to treat the weeds. Technicians either drop slow-release fluoridone pellets into the weeds or spray the area with liquid Diquat, which encapsulates the weeds and eradicates them quickly. Since the Delta is adjacent to farmland, DBW is limited in the amount of chemicals it can use.

Gloria Sandoval, California State Parks deputy director of public affairs, said that while the Aquatic Invasive Plant Control Program (AIPCP) allows treatment to begin March 1, the pandemic — along with weather and water temperature — prevented the DBW’s operations. She noted that concern for the safety of employees is a priority, and personal protection equipment and classes on social distancing had to be given to each employee before work could begin.

“In order for the herbicide to be most effective, DBW has been working with a model that helps to predict the best time to apply herbicides to effectively target the growth habits of the plants,” Sandoval said in an email to The Press. “Additionally, this year COVID-19 also played a key factor in the delay of the 2020 AIPCP.”

Sandoval added DBW began treatment this month, following the strict guidelines and monitoring requirements outlined by the State Water Resources Control Board. She said it was unknown whether treatments would be able to catch up with the weeds’ head start on the growing season.

Once the weeds are killed by one of the two treatments, their dead foliage can cause its own set of problems — decaying plants act as fertilizer for other weeds as well as the blue green algae, which grow in shallow, stagnant parts of the Delta in hot summer weather. The solution may be to dredge bays on the west side of town, especially those like Cabrillo Bay that are close to the opening of the Delta and have a constant flow of silt. The catch? Dredging all the bays would be a multimillion dollar project.

“Since the dirt in all our bays is owned by Reclamation 800, I am wondering what they are planning to do as Cabrillo is now only 7 feet deep at low tide and will continue to get worse,” Rossi said. “I understand most of the bays on the west side are very shallow and need attention.”

Currently, Reclamation 800 District does not have any permits to put any kind of chemical into open water or any plan to dredge bays.

In his quest to keep Discovery Bay beautiful, Mattison and the DBCF have also aligned with the Central Valley Water Board to help mitigate the blue green algae, applying for and receiving an $80,000 grant for a load study and potential remedies to help the dangerous algae in all 32 bays and Willow Lake.

While he waits for the weeds to be sprayed, Rossi said he is hopeful he will get his boat out this summer and thankful to Mattison.

“Jim has been as asset to the community,” Rossi said. “We live here because we love the water, and when you can’t embrace what you love, it’s makes you wonder, what do you do?”

For more information about aquatic weed treatment, email Mattison at