News

Understanding Cladophora: What Green Algae Means for Seneca Lake

GENEVA, N.Y. – If you’ve spent time along Seneca Lake’s shoreline during the summer, you may have noticed green, stringy algae clinging to rocks or washing up in mats along the water’s edge. This is likely Cladophora, a naturally occurring green algae that is common in clear, nutrient-rich freshwater lakes.

In small amounts, Cladophora plays a helpful ecological role by providing food and shelter for aquatic insects and small fish. However, when it begins to grow excessively, it becomes a nuisance (thus the nickname nuisance algae). Dense mats of Cladophora can detach, drift ashore, and decay on beaches and waterfronts, creating unpleasant odors, harboring bacteria, and affecting water quality and recreational enjoyment.

There are several factors that contribute to increased Cladophora buildup. High levels of nutrients, particularly phosphorus, stimulate algal growth. These nutrients often come from agricultural runoff, stormwater, failing septic systems, and lawn fertilizers. Additionally, the presence of invasive zebra and quagga mussels in Seneca Lake has changed nutrient cycling and water clarity, creating ideal conditions for Cladophora to thrive. While much of the scientific focus has been on Cladophora in the Great Lakes, similar concerns are growing around Seneca Lake.

Members of Pure Waters are seeing more instances of shoreline algal mats, prompting concern and the need for more structured data collection. That’s why we at Pure Waters want to establish a more formal reporting structure around the lake. By using the Survey123 Reporting Tool even you the reader can get involved. This citizen science initiative encourages shoreline residents and lake users to report Cladophora sightings—whether sparse or extensive—along with photos, location details, and estimates of coverage. Your observations are important. By participating, you help scientists and Seneca Lake Pure Waters Association better understand the causes and extent of Cladophora growth and work toward solutions that preserve the health and beauty of Seneca Lake.

Written by Jackson Abreu, Pure Waters Summer Intern

Learn more about Pure Waters

To learn more about Cladophora: https://senecalake.org/preserve-protect/monitoring-data-collection/cladophora/
To learn more about donating: https://senecalake.org/giving/

Seneca Lake Pure Waters Association is a 501(c)3 organization committed to preserving, protecting, and promoting the abundant resources of the largest Finger Lake. Seneca Lake is a source of drinking water, recreation, and economic opportunity for the greater community and its visitors. Our programs and partnerships make it possible to monitor water quality, educate the public, and evaluate threats to ensure the a healthy future for Seneca Lake and those who depend on it.