From Google, but I remember hearing of some significant agricultural spills/runoff events that are likely contributing factors for the excessive algae blooms:
Reports from 2017 and 2021 mention significant agricultural runoff incidents affecting Cayuga Lake. A manure spill in 2017 reached the lake via Salmon Creek after melting snow carried runoff from fields where manure had been spread due to a structural issue at a nearby farm's manure storage lagoon. In 2021, an estimated 100,000 gallons of liquid manure overflowed from a storage pit at Ashland Farm, reaching a tributary of Great Gully Brook which flows into Cayuga Lake.
Impact on Cayuga Lake and the Surrounding Region
These incidents, along with ongoing agricultural runoff, contribute to nutrient loading in Cayuga Lake. Excess nutrients, particularly phosphorus and nitrogen, can lead to harmful algal blooms (HABs) that can pose health risks to humans and animals.
Harmful Algal Blooms: The presence of HABs has been observed in Cayuga Lake since 2017, and has been documented to cause beach closures and impact water quality.