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Health officials are urging residents and visitors to stay out of the water in Discovery Bay after dangerous levels of harmful algae were detected.
Marisa Van Dyke of the State Water Resources Control Board reported that recent lab results from water testing showed “significant” harmful algal blooms occurring in Discovery Bay. Multiple locations recorded a “danger” level, the highest threshold, she said.
Numerous Discovery Bay residents also had reported harmful algae, including in areas not sampled on June 4, she added.
The Regional Water Board staff confirmed danger levels of harmful algal bloom in water and scum samples from three coves within the bay — near the Discovery Bay Yacht Club, Windward Bay and Clipper Bay. The latter two had levels nearly 13 times higher than is safe.
Joe Doser, supervising environmental health specialist for Contra Costa Environmental Health, said the levels were “much higher” than last year.
Other impacted coves and bays within Discovery Bay include Reese Cove, Discovery Bay Harbor and Beaver Bay, according to officials. The bay is located in the southern area of the Delta with connections to Old River and Clifton Court Forebay.
Doser said officials are still studying why the levels are higher this year. One theory is the water was more stagnant because it didn’t rain as much.
“Poorer water flows are a factor,” he explained.
Doser recommended that people and pets avoid the water and not eat fish or shellfish caught in the bay.
“Dogs in particular — they get in the water and go crazy and lick their fur, and with their smaller body weights, they are more at risk,” he said.
Exposure to cyanobacteria and associated toxins can cause eye irritation, skin rash, mouth ulcers, vomiting, diarrhea and cold or flu-like symptoms, according to California Water Boards.
Discovery Bay resident Michael Greggans, who lives on Clipper Bay, said he’s not taking any chances so his kayaks will sit idle on boat ports above the pea-soup colored water surrounding his dock. He no longer swims in the bay’s water either.
“We had no idea it would be like this,” said the 11-year Discovery Bay resident. “You pay quite a premium to be out here and enjoy the water and you really can’t. It defeats the purpose.”
County health officials further recommended against touching or handling blue-green algae in the water or scum on the shoreline. It is also unsafe to drink or cook with water in these areas, they said in a statement late Monday. Environmental Health also has warning signs available for residents and businesses to post if needed.
The buildup of harmful algae, or cyanobacteria, creates a green, blue-green, white, red or brown coloring that may look like thick paint floating on the surface of slow-moving waterways. Some also form mats at the bottom of a water body, and others float at various depths, California Water Boards officials said.
Blooms are most common between June and September. They grow in warm, stagnant and nutrient-rich water, and are becoming increasingly common both in California and nationwide, according to the Contra Costa Environmental Health website.
To report a suspicious bloom, go to https://mywaterquality.ca.gov/habs/index.html.
Visit cchealth.org/eh/hab to learn more about harmful algae blooms. Or, see a video from the Calfornia Department of Water Resources at https://www.youtube.com/watch?time_continue=63&v=AqbM0ivJayw&feature=emb_title.