DISCOVERY BAY (KPIX 5) — Ignoring a warning issued by health officials, swimmers and their pets on Friday were still using a popular body of water in eastern Contra Costa to cool off, even though it’s now contaminated with toxic algae.

Signs have gone up in Oakley and Discovery Bay warning of the toxic algae that crops up in the Delta this time of year. People have been told not to swim or fish.

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As pets dive into the water of Discovery Bay, their owners said they aren’t too worried about the blue-green algae warning posted nearby.

“I feel more comfortable over here. I can see the water, it’s more clear,” said dog owner Dennis Deutscher.

Even some families are ignoring the warning, despite Contra Costa County health officials telling people not to swim in the water.

“I’ve been watching the kids out here for two days, swimming. The kids seemed to be fine and enjoying it,” said Deutshcher.  “The dog is well.”

“We’re in the water every night, myself, my daughter and my wife. I would say there’s a considerable amount of overreaction,” said Dave Black, a Discovery Bay resident who is also a frequent diver.

Many believe that they’ll be fine as long as they stay away from the toxic algae.

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“There could still be enough algae growing there to producing the toxins at a harmful level,” explained Joe Doser, a representative of Contra Costa Environmental Health.

Health officers worry that a warm weekend will draw even more people and dogs into the toxic water.

They’re warning people that the levels of toxin from the blue-green algae at Yacht Harbor are the most dangerous–dangerous to the point that they shouldn’t eat the fish that inhabit the water.

Elsewhere in Discovery Bay, health officers don’t want people and pets to even touch the water at all.

In Oakley, Easy Bay Regional Park District officials found similar toxic blue-green algae at the Big Break Regional Shoreline kayak launch and also around the fishing dock.

“We have not had pet fatalities in this county. We did have some human illnesses,” said Doser. These illnesses happened last year; some of the signs included vomiting, diarrhea, and fever.

Some people are taking the warning seriously. “I have a daughter and I’m pregnant,” said Anna Cook, another Discovery Bay resident. “I’m staying out of the water.”

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Health officials have been putting out these warnings since 2015. They estimate that the problem should dissipate by Fall, when the temperatures get cooler.