After record outbreaks in 2011 and 2013, the presence of harmful blue-green algae in Lake Erie continues to lessen but still remains significant enough to be a possible threat to drinking water.  Lake Erie provides drinking water for more than 11 million people on both sides of the border between US and Canada. Filtration plants are forced to pay an additional cost of up to $3,000 a day, which adds up to over a million dollars annually, for extra chemical treatment when algae blooms are intense.

The algae blooms in Lake Erie tend to be a particular type of blue-green algae called microcystis, which is a thick greenish, grainy material that accumulates along the lake shore. Dried microcystis scum can contain high concentrations of bacteria for several months. Therefore, toxins dissolve in the water even when the cells are no longer alive and use up the oxygen in the cold bottom layer of water.

Experts use a combination of satellite imagery, computer modeling, and water samples gathered by multiple agencies to create forecasts for the year. This year’s forecast calls for 24,250 tons of blue-green algae to overtake Lake Erie. The accuracy of these forecasts can be affected by unexpected weather, as rains can wash in heavy loads of phosphorus fertilizer that foster the growth of the algae and winds can push blooms. Additionally, blue-green algae are exacerbated by phosphorus runoff from agriculture, lawn care, sewage, industrial wastewater, and other human activity.

High levels of algae toxins can potentially be deadly for people and can therefore cause filtration plants to close down and issue orders to residents not to drink the water. Although there are currently no United States public health standards in regard to algae toxins in drinking water, the toxin levels in 2013 were three times higher than the recommended safety level of the World Health Organization. As low levels of algae toxins can even kill farm animals and pets, both the EPA and the Centers for Disease Control hope to release the first national guidelines by the end of this year.