The biggest draw at The Park at New Melle Lakes is off-limits for now, after officials shut down the main lake on Friday because of a confirmed blue-green algae bloom. Rangers have roped off access to the Big Lake and posted warning signs, so swimming, boating and any other water activities are paused while crews size up the bloom and start treatment.
What officials are saying
FOX 2 reported that the Missouri Department of Natural Resources confirmed cyanobacteria in the park’s main lake and that the site is expected to stay closed through at least this weekend. St. Charles County Parks told the station that the Big Lake is closed to every kind of on-the-water activity while crews work to treat and knock back the algae.
DNR response and where to check updates
The Missouri Department of Natural Resources posted photos that show thick surface scums across the water and urged residents to keep an eye on reported blooms using its online HAB reports map. The Missouri Department of Natural Resources map lists suspected and confirmed blooms and explains how the public can report a sighting. DNR staff and county crews say they will keep testing water samples and coordinating mitigation work at the park while the lake stays closed.
Why blooms happen and why this one stands out
According to the U.S. Environmental Protection Agency, harmful algal blooms tend to pop up when warm, calm water combines with extra nutrients like nitrogen and phosphorus, which gives algae an easy buffet. These blooms are most common in summer and early fall, yet Missouri DNR called the New Melle bloom in early April unusual, FOX 2 noted. Local runoff and ponded water in small lakes can still set the stage for early-season blooms in some years, even when the calendar says spring has barely started.
Health risks and what to watch for
Centers for Disease Control and Prevention guidance notes that cyanobacteria can produce toxins that irritate skin and may cause nausea, breathing issues or liver problems if the water is swallowed or inhaled. Pets, especially dogs that like to drink and splash in lakes, are at high risk and can become seriously ill or die after exposure. If people or animals show symptoms after contact with the water, officials advise reaching out to a medical professional or veterinarian and reporting the incident to local health authorities.
How to stay safe and where to check
For now, officials say to steer clear of any discolored water or visible surface scum, keep pets and livestock far from the shoreline and skip eating fish from the lake until the advisory is officially lifted. Residents can track status updates on the Missouri Department of Natural Resources HAB reports map and watch the St. Charles County Parks page for reopening notices. For specific questions, the county parks department lists its main phone number on its website.
