ITHACA, N.Y. — Over the weekend, Cayuga Lake saw its largest widespread Harmful Algal Bloom (HAB) of the season, engulfing part of the Northeastern shoreline in layers of curdling green. The first reports of the bloom started coming in on Thursday, Sept. 12, said Alyssa Johnson, the HAB monitoring coordinator for Community Science Institute. By Friday, the bloom was well established and persisted until Tuesday. There were no blooms reported Wednesday, Johnson said.Over the course of the bloom, the institute received over 13 reports, all relating to the same bloom, Johnson said. Freshwater HABs are generally caused by cyanobacteria, which are microscopic organisms that photosynthesize like plants, giving the blooms their distinctive color. These cyanobacteria release a toxin known as microcystin, which can “pose health risks to people and animals” through contact, ingestion or inhalation, according to the Department of Environmental Conservation’s (DEC) HAB website. HABs occur when there is an excess of nutrients in a water body, and in the case of Cayuga Lake, the primary source of nutrient pollution comes from fertilizers used in agriculture.The large bloom on Cayuga Lake spanned from Long Point State Park in Aurora all the way north to the town of Cayuga, which accounts for a nearly 17-mile stretch of shoreline, although the bloom did not affect the entirety of the shoreline and most appeared some distance offshore, Johnson said.“It was reported more than halfway across the lake towards the western shore, although we are unclear where the western ‘edge’ is. It likely just fades out,” according to CSI’s Facebook post. Johnson called the bloom “insane” and “gross.” She added that blooms can be fluid and dynamic, meaning the size and shape can change somewhat rapidly. Between Sept. 10 and Sept. 17, the Community Science Institute received at least one HAB report every day, making it the longest stretch of consecutive HAB reports since August, when the institute received HAB reports for five days straight. While there were no reported HABs on Wednesday, four HABs were reported to CSI on Thursday. The DEC suggests people, pets and livestock avoid contact with “any floating mats, scums, or discolored water.” If contact occurs and one experiences symptoms such as vomiting, nausea, diarrhea, skin, eye or throat irritation, allergic reactions or breathing difficulties, they further suggest seeking immediate medical attention.However, the DEC does not have the authority to close the lake, even in the case of a widespread HAB. The agency’s HAB Action Plan for Cayuga Lake outlines several ways to reduce the amount of nutrients that make it into the lake, like limiting lawn fertilization, maintaining septic tanks, installing and maintaining shoreline buffers and reducing erosion and stormwater runoff.Otherwise, there is not much to do when a HAB occurs, Johnson said. In the future, she hopes that CSI’s HAB monitoring program will incorporate a way to be proactive rather than reactive, she said. “I believe the angle that we really need to take is prevention, and that has a lot to do with regulation of agricultural practices and systems,” she said.The post Massive, multi-day Harmful Algal Bloom hits Cayuga Lake appeared first on The Ithaca Voice.