Authorities are warning the public after detecting elevated levels of a dangerous algal bloom that has emerged in a New Hampshire lake. After collecting samples from Lake Monomonac on July 17, authorities have determined that it has exceeded the threshold of 70,000 cells per milliliter of what is known as blue-green algae, or cyanobacteria.

They found Aphanocapsa, Anabaena, and Woronichinia. The largest blooms were found near the shore. While this is a naturally occurring phenomenon, this sudden bloom was the result of an excess of phosphorus in the water, and it can prove hazardous to the health of humans.

Exposure to cyanobacteria can cause serious problems in the human body, ranging from skin irritation to liver damage.

“An elevated cyanobacteria cell concentration has been measured in Long Pond, Pelham, NH,” reads a statement from the New Hampshire Department of Health and Human Services. “Samples collected at the Pelham Town Beach on July 17, 2017 revealed that the state threshold of 70,000 cells/ml or greater of cyanobacteria was exceeded. The cyanobacteria were identified as Anabaena, Microcystis and Woronichinia. As a result, the New Hampshire Department of Environmental Services (NHDES) has issued a cyanobacteria warning for those who recreate on Long Pond. The current bloom is variable with some lake portions free of scum sightings, while other areas have accumulations of cyanobacteria along the shorelines or beaches. Samples collected on July 19 were clear; however the bloom had resurfaced on July 20 in high concentrations.”