Children play at Acworth Lake, adjoining Allatoona Lake, in this file photograph from 2017.

The latest water quality tests of Lake Allatoona show no toxins associated with blue-green algae, the Cobb County-Marietta Water Authority says.

Three authority employees gathered water samples from five different parts of the lake Friday, which were then tested at the authority’s Acworth laboratory for three types of toxins associated with blue-green algae — microcystins, cylindrospermopsin and anatoxin-a.

All water samples showed zero parts per billion of each toxin, the authority’s operations director Cole Blackwell told the MDJ on Friday afternoon.

He said there are no regulations for these toxins, only recommendations, so it’s hard to state with certainty the level of risk for people and their pets swimming or playing in the lake.

“I wouldn’t venture to say what’s safe or not,” he said. “But if we don’t come up with anything at a parts per billion level, then the water is safe. We are confident as of today that there’s nothing going on that we need to be concerned about.”

Despite the results, the authority will continue to sample and test Lake Allatoona water for these specific toxins every Friday through the summer while concerns of toxic algae blooms remain high, Blackwell said.

Area residents have been worried since a Marietta couple’s dog died shortly after it played and swam in the lake near Red Top Mountain last Saturday.

Dog deaths associated with toxic algae have also been reported in North Carolina and Texas lately, and recent testing revealed blue-green algae found in Lake Olmstead near Augusta contained four types of dangerous bacteria.

No autopsy was performed on the Marietta couple’s dog but they say their veterinarian suspected poisoning from toxic algae due to the dog’s symptoms and fast deterioration.

Samples from Lake Allatoona taken by the Georgia Environmental Protection Division on Monday, two days after the dog died, also showed no harmful levels of toxins, the agency said, adding it suspects the dog might have died from a weekend toxic algae bloom that had already dissipated by Monday.

The EPD, which will continue its regular monitoring of water quality at Lake Allatoona, recommends people and pets avoid going into any lakes or ponds that appear bright green or the color of pea soup — a clear indication of the presence of toxic algae.

The Cobb County-Marietta Water Authority sources drinking water from Lake Allatoona, at a point near Acworth where the lake meets Interstate 75.

Blackwell says the weekly blue-green algae toxin testing is above and beyond the authority’s regular water quality testing of Lake Allatoona, which includes monthly sampling at the lake’s dam and constant sampling at the drinking water source.

“We are going to sample and test water on a weekly basis from our intake and our finished water,” he said, referring to the drinking water the authority treats and sells wholesale to 11 retailers, including Cobb County and the cities of Marietta, Austell, Powder Springs and Smyrna.

Blackwell said Friday’s water samples were taken from different parts of the “Allatoona arm” of the lake, between the dam and the Lake Acworth spillway, as well as an area near Red Top Mountain.

Those unsure about the safety of any lakes, reservoirs or ponds this summer are advised to avoid any scummy or bed smelling water, especially if it contains algae or dead fish, according to several environmental and health organizations including the EPD and the Atlanta-based Centers for Disease Control and Prevention.

Those agencies say toxic algae blooms in slow moving water when it is exposed to a lot of sunlight and nutrient sources.

Blue-green algae is a common name for cyanobacteria, which get energy through photosynthesis and produce toxins that can be harmful to people and animals.

Lake Allatoona, covering parts of Cobb, Bartow and Cherokee counties, is operated by the U.S. Army Corps of Engineers, which has not responded to an MDJ request for comment.

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