09/19/2025
FOR IMMEDIATE RELEASE:
September 19, 2025
Contact: Jill Bronaugh
Public Health Advisories for Kansas Waters Due to Blue-Green Algae Mats
TOPEKA – The Kansas Department of Health and Environment (KDHE) and the Kansas Department of Wildlife and Parks (KDWP) have issued a public health advisory due to blue-green algae mats.
The KDHE Harmful Algal Bloom (HABs) response program has recently identified a new and evolving health concern at a Kansas public waterbody associated with another species and growth form of blue-green algae, Harmful Algal Mats (HAMs). HAMs are blue-green algae that grow attached to the bottom of the waterbody or other surfaces. However, these blue-green algae mats can become detached and float freely where they may wash up on shores/banks. In addition, HAMs can be mixed with non-harmful green algae and other aquatic vegetation.
HABs and HAMs can produce the same toxins, but their growth types are different, as do the advisory messages and signage issued for them. HABs are composed of high densities of usually small, microscopic blue-green algae dispersed in the water column that can change the color of water and often form a surface scum, especially during warmer months. HABs can be unpredictable, and conditions can change rapidly. On the other hand, HAMs can reside in water that looks clear and clean and may often appear as excess growth that is dark green, blue-green, brown or black in color that carpets or develops a film on the bottom of the waterbody or other surfaces. HAMs may continue to persist and grow year-round in affected waterbodies. In flowing waters, such as streams and rivers, HAMs may disperse and move down stream.
The health risk from HAMs is greatest when exposure occurs through ingestion and when contact or disturbance of algal mat material occurs (particularly for small children and dogs). KDHE HAB Response Program will notify public waterbody managers if HAMs are detected at the waterbody while responding to algae bloom complaints and recommend that signage be posted.
New HAM Advisories:
South Fork Solomon River at Osborne (Kill Creek downstream to the confluence of Glen Elder Reservoir/Waconda Lake), Osborne County
New HAM advisories are only posted and released once identified and confirmed.
If you notice HAM signage posted at the waterbody or excess algal growth that appears dark green, blue-green, brown or black in color, be aware that potential health risks may be present when engaging in recreational activities. KDHE HAB Response Program recommends the following precautions be taken at HAM affected waters:
Do not allow people or pets to eat algal mats or ingest lake or stream water.
Do not touch or contact algal mats. Use caution when engaging in recreational activities, especially primary contact recreation, such as swimming. Wash with clean water after skin contact with affected water.
Do not transport algal mats to other waterbodies and follow KDWP’s guidance for cleaning boats and equipment.
For more information on Harmful Algal Mats or to see all waterbodies confirmed to be affected by HAMs, please visit:www.kdhe.ks.gov/HAM.
