Indian Lake to Undergo Preventative Algae Treatment Thursday

WORCESTER, Mass. - The City of Worcester Department of Sustainability and Resilience has hired contractors to apply a treatment of the algaecide copper sulfate to Indian Lake on Thursday, August 14, 2025.

This is a preventative treatment, and there is currently no threat of harmful algae exposure. On the day of the treatment, the municipality advises that individuals stay out of the water, discontinue boat use, and keep pets out of the water. All persons are advised to discontinue using water from Indian Lake for irrigation of plants or lawns or watering livestock. Beaches will be posted prior to the application. Water use restrictions are scheduled to be lifted the following day.

Copper sulfate is a safe and effective way to control the growth of a harmful, toxin-producing algae known as cyanobacteria. When their population gets high enough, the blue green algae are able to produce toxins that are harmful to humans and pets. The application of copper sulfate products is a common practice to maintain a healthy lake and poses minimal risk to humans and animals after application is complete. This application has been approved by the Worcester Conservation Commission.

For more information on toxin-producing algae (i.e., cyanobacteria) please see our video series "The Blue Space Minute" at https://www.youtube.com/watch?v=1ZL9RMDapJc .