LAKE AFTON, KS — A favorite destination for Kansans seeking a summer escape, Lake Afton, is currently under a blue-green algae warning, prompting public health officials to urge caution and vigilance among park visitors. The Kansas Department of Health and Environment (KDHE) issued the advisory for the popular Sedgwick County lake on Friday, August 1, 2025, marking the first such warning for Lake Afton this season.
The warning comes as temperatures climb and water conditions become more conducive to the rapid growth of these microscopic organisms. While often referred to as “blue-green algae,” they are technically a type of bacteria known as cyanobacteria. Under the right conditions, which include warm, nutrient-rich water and plenty of sunlight, these organisms can multiply exponentially, creating what is known as a harmful algal bloom (HAB). The visual result is often a discolored, pea-soup-like appearance or a layer of green, blue-green, brown, or red scum on the water’s surface.
For Lake Afton, this warning status means that a harmful algal bloom is either expected or already present. As a result, KDHE and Sedgwick County officials have posted signage at all public access points, advising visitors to avoid contact with the water. The primary concern is the potential for these blooms to produce toxins, known as cyanotoxins, which can pose significant health risks to both humans and animals.
The most dangerous form of exposure is ingestion, but contact with the skin or inhalation of water droplets can also lead to adverse health effects. Symptoms in humans can range from skin rashes and irritation to more severe issues like vomiting, diarrhea, fever, sore throat, and headaches. Pets, particularly dogs, are especially vulnerable to the toxins. Their natural inclination to swim in and drink from the water, or to lick their fur after swimming, can lead to serious illness or even death within a matter of hours. The KDHE advises pet owners to keep their animals away from the water entirely and to not allow them to eat dried algae along the shore.
Despite the warning, not all recreational activities are off-limits at Lake Afton. Boating and fishing are generally considered safe, but with specific precautions. Anglers are instructed to thoroughly rinse their catch with clean, fresh water and to consume only the fillet portion, discarding all other parts. It is also recommended to avoid direct contact with the water as much as possible, and to wash with clean water as soon as contact occurs. The inhalation of spray or aerosols from the water is also a potential risk for some individuals.
The unpredictability of these blooms makes it difficult to say how long the warning will remain in effect. Algal blooms can develop rapidly and can be moved across a body of water by wind and currents. The KDHE continuously monitors affected lakes and will lift the advisory once cell densities and toxin concentrations fall below dangerous levels. In the meantime, the health department and park officials are urging the public to use their best judgment and err on the side of caution.
The recurring nature of blue-green algae warnings is a growing concern for Kansas lakes. These blooms are often fueled by excess nutrients, such as nitrogen and phosphorus, that enter the water from sources like agricultural runoff, wastewater treatment plants, and urban landscapes. The combination of these nutrient-rich conditions with the state’s hot, sunny summers creates a perfect storm for cyanobacteria to thrive. While Lake Afton is a public park and a vital part of the Sedgwick County community, it also serves as a crucial reminder of the environmental challenges facing Kansas’s waterways.
For residents and visitors looking for updated information, the KDHE website provides a comprehensive list of all Kansas lakes under a watch, warning, or hazard status. Additionally, the Sedgwick County Parks Department has a dedicated hotline for Lake Afton updates. While the blue-green algae warning may put a damper on some summer plans, officials emphasize that the most important thing is to prioritize public health and safety. Until the warning is lifted, Lake Afton’s shores will remain a place for contemplation rather than a destination for a cooling dip.
