State water officials have once again sounded the alarm over dangerous blue-green algae levels in San Luis Reservoir in Merced County.
On Thursday, the Department of Water Resources said in a news release that “increased amounts of microcystins,” a byproduct of the bacteria, in the 2 million acre-foot body of water prompted it to elevate the advisory to “danger” from “warning” until further notice.
O’Neill Forebay, however, is not affected by algal bloom advisories.
Boating is allowed but swimming and any other activities that involve contact with the water are not considered safe and strongly discouraged, water officials said. The public is also being advised to avoid eating fish from the lake, and to keep their pets way from the water as well. Common water purification techniques will not remove the toxins.
Officials had taken the same action last month, before lowering the advisory 10 days later. Even while at “warning” level, officials urged people to avoid physical contact in the popular recreation spot nestled in the Diablo Range not far from Interstate 5 and 15 miles west of Los Banos.
Bloom conditions are subject to change, as wind and waves can move or concentrate the blooms into different regions of the reservoir, officials said. The bloom can form into mats, scum or foam at the surface and along the shoreline.
Touching the algae-infested water can cause eye irritation, allergic skin rash, mouth ulcers, vomiting, diarrhea and cold- and flu-like symptoms.
Pets are “especially susceptible,” according to the Department of Water Resources, because they typically lick their fur after drinking water. In the summer of 2017, a toxic algae bloom in a Napa County pond killed two dogs, The Bee previously reported.
If someone believes they have been poisoned by the algae, they should seek medical treatment immediately, officials said.