ST. CHARLES COUNTY — County officials said rains expected over the next several days should help break up toxic algae blooms in lakes at two parks here.
Officials this week discovered cyanobacteria, or blue-green algae, at a lake in Quail Ridge Park, near Wentzville, and in the pond at the dog park at Broemmelsiek Park, near Lake Saint Louis — forcing them to close the dog park to keep humans and dogs safe from toxins produced by the algae.
“We recommend that people, pets, and livestock avoid contact with any water body suspected of having a cyanobacteria bloom for at least two weeks after all visual signs of the bloom after dissipated,” Scott Robinett, a state environmental manager, said in an email.
Toxins released by cyanobacteria can be fatal for pets and make people sick. Blooms spike in the summer across the Midwest, and are becoming more frequent each year, globally, as temperatures warm. Reports of dogs getting sick have hit Broemmelsiek in previous years.
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Cyanobacteria play an important role in ecosystems — they can take nitrogen from the air or water and incorporate it into an organic molecule, which makes it useable by plants, fungi, and animals.
“It’s a natural phenomenon that’ll occur in any natural body of water,” said Ryan Graham, director of parks for St. Charles County. “It’s been around since before the dinosaurs.”
And cyanobacteria are not always harmful — but they can be if they produce toxins, become too dense, use up the oxygen in the water or release harmful gases.
Missouri has confirmed four blooms this month, two in St. Charles county, and two in the Kansas City area, Robinett said.
The bloom at Broemmelsiek is what’s called a Microcystis, said Graham, triggered by extreme temperatures.
Microcystis is the most common bloom-forming cyanobacteria in the world, and produces toxins called “microcystins” that can poison mammals, according to the US National Office for Harmful Algal Blooms.
In humans, symptoms of cyanobacteria exposure include headaches, rash, stomach pain, and nausea. Symptoms for pets range from sleepiness and lack of appetite to foaming at the mouth.
“When temperatures are that high for that many days in a row, keep pets out of natural bodies of water,” said Sara Evers, acting director of public health for St. Charles County. “Once they get it on their coats, they’ll try to lick it off, which will make things worse.”
The St. Charles County Parks Department monitors cyanobacteria levels in natural bodies of water monthly. Sites with high cyanobacteria populations are tested for toxin production, and closed to the public if dangerous. There are also treatment options for water with high levels of cyanobacteria, including adding non-toxic dye to block out sunlight and bring water temperatures down, said Graham.
But rain, said Evers, is one of the natural solutions: It cools down waterways, and keeps water circulating.
So the storms coming may arrive at just the right time.
“Rain is one of the big things that beats down the algae blooms and disrupts its cycle — this is definitely something we needed,” said Graham.
Though the rain is expected to cause the bloom to dissipate, toxins produced by cyanobacteria can hang around for several weeks after the bloom is gone.
Officials will continue testing park water to ensure the park only re-opens when the danger to humans and pets is gone.