A blue-green bummer
Bloomof potentially toxic bacteria sparks tests of water samples
DISCOVERY BAY — As government officials wait to find out whether a type of bacteria has turned Discovery Bay’s waterways toxic, they are cautioning residents to play it safe by staying dry.
“You should not be playing in the water. We don’t want you to be drinking the (river) water there,” said Sue McConnell, section chief of the Central Valley Regional Water Quality Control Board. “Don’t be engaged in any kind of activity where you could be ingesting it.”
The warning does not extend to drinking water, however, which comes from the community’s wells and remains safe to drink.
Responding to residents’ complaints about the visible proliferation of the potentially harmful bacteria commonly known as bluegreen algae, Contra Costa County health officials last week began collecting water samples from channels in the southwest area of the upscale enclave where many homes have private docks and water sports are king.
On Tuesday they turned their attention east to Discovery Bay’s marina and expanded the scope still farther on Wednesday.
When preliminary tests indicated that blue-green algae had produced toxins, the county sent the samples to state and federal labs to determine whether they are at levels that warrant concern.
Hot weather, long daylight hours, slow-moving water and high levels of the nutrients nitrogen and phosphorus can trigger the bacteria to multiply to the point that they turn water bright green or coat the surface with scum.
These so-called blooms do not always signal the presence of toxins, however, and McConnell noted that even in cases where they do exist, they don’t necessarily pose a hazard — it’s the concentration that matters.
Nevertheless, they had water sports enthusiast Lisa Black reconsidering a dip in the water.
“It was really scary looking,” she said of the water where she and her husband live in Dolphin Cove, noting that over the past several weeks it has turned an “electric green.”
“I’ve never seen it this bright.”
In high enough concentrations, cyanobacteria, the official name for blue-green algae, can cause an array of physical reactions from rashes and eye irritations to diarrhea, vomiting, fever, sore throats, headaches, and muscle and joint pain. If enough is ingested, it can lead to serious illness and even death.
The bacteria also has proved harmful to animals, so advisories typically include warnings against allowing dogs to swim in affected areas.
McConnell emphasizes that the presence of cyanobacteria is nothing new to far East Contra Costa County nor unique to it.
“It’s not just happening in Discovery Bay,” she said, noting that blooms have been found in the Stockton area, Clear Lake and the Pit River arm of Lake Shasta. “It’s happening statewide, nationwide. In fact, scien- tists are finding it throughout the world.”
As the days grow shorter, temperatures drop and rain stirs up pockets of sluggish water, the blue-green algae will disappear, McConnell said.
In the meantime, there are things residents can do to discourage its growth.
Don’t use more fertilizer than necessary because the runoff could serve as food for the bacteria, McConnell said, adding people should pick up after their pets because animal waste can have the same effect.
If test results show dangerous levels of toxins, the county will provide warning signs for Discovery Bay officials to install. The results will be posted on the county’s website and Facebook page.
Kevin Graves, a board member of the Discovery Bay Community Services District, typically goes kayaking and paddleboarding from the backyard of his deep-water lot home, but he’s putting those activities on hold temporarily.
“At this point I probably wouldn’t jump in the water in my backyard, just as a precaution,” he said.
Longtime resident Dave Black, however, is not changing his routine at all.
As the owner of a boat repair business, he routinely immerses himself in the marina’s water to fix vessels’ propellers.
And so far, Black says he’s doing just fine.
“No third eye yet and the fish are still alive,” he laughed.