In August 2014, the City of Toledo was forced to warn 500,000 residents not to drink their tap water because of contamination caused by a harmful algae bloom (HAB) in Lake Erie. During that same summer, the Army Corps of Engineers (Corps) and the Kentucky Division of Water (DOW) issued warnings to recreational users of 10 Kentucky lakes, including Barren River, Nolin River, Green River, Rough River and Guist Creek, that algae had been observed at levels that could cause health effects from swimming in or ingesting the water. The increasing number of warnings has created concern among both citizens and government agencies responsible for the safety and health of their residents.

HABs are caused by a confluence of particular factors, including the presence of nutrients – particularly nitrogen and phosphorous, sunlight and slow-moving water. The nutrients are generally attributable to run-off from agricultural or industrial activity.

Kentucky is joining 11 other states in the Mississippi River Basin in consolidating efforts to address nutrient problems in waters. DOW is currently drafting a nutrient reduction strategy to guide reduction of nutrient loading and develop a watershed-specific plan to manage nutrients.

Some HABs are more toxic than others, as the Toledo incident demonstrates. Rivers are not as susceptible to HABs, as the moving water reduces the possibility of the proper conditions for algae growth.

On Oct. 20, 2014, DOW issued a Fact Sheet to water treatment systems operators to address the situation that was faced in Toledo. Operators are to monitor their water inputs for cyanobacteria, and develop a treatment plan for removing or treating the detected algae. The treatment plan should also consider using an alternate source of water until the HAB has been addressed, as well as determining particular treatment options for various toxins. It is unclear at this time what costs individual treatment systems operators will incur to avoid a Toledo-like shutdown.