Upton's Pratt Pond one of many waterbodies affected by harmful algae
In July, a public health advisory was posted at Upton’s Pratt Pond which was closed due to harmful algae. Courtesy photo
By Theresa Knapp
UPTON – In July, Pratt Pond joined a growing list of waterbodies throughout the Commonwealth of Massachusetts to close due to harmful cyanobacterial (algal) blooms. It has since reopened.
Information on www.mass.gov states, “Cyanobacteria – also known as blue-green algae – occur naturally in freshwater, but can multiple quickly under certain conditions, creating a highly concentrated area known as a cyanobacterial harmful algal bloom. Algae blooms can be harmful to people and animals.”
According to the National Institute of Environmental Health Sciences, a division of the National Institutes of Health, “Algae are always in natural bodies of water like oceans, lakes, and rivers, and a few types produce toxins. A harmful algal bloom (HAB) occurs when toxin-producing algae grow excessively in a body of water.”
In July, a public health advisory posted by the Upton Board of Health – at Pratt Pond and at www.uptonma.gov – warned the water was “unsafe for people and pets” and further cautioned:
• Do not swim
• Do not jet ski
• Do not boat
• Do not swallow water
• Do not consume fish
• Keep animals away
• Rinse off after contact with water
A post by the Upton Board of Health stated, “On 7/16/25, we were advised by the MASS Dept. of Public Health of a potential algae bloom at Pratt Pond. Due to this information, we have closed the pond to any form of recreation until it has been cleared by the Mass. DPH. Once water testing indicates the pond has cleared, we will re-open the beach to the public.”
Visit www.uptonma.gov, for the most up-to-date information.
Other local areas affected by the algae blooms include Blackstone Canal in Uxbridge, and the Hopkinton Reservoir in Hopkinton/Ashland. Visit www.mass.gov for a list of waterbodies “that have been reported to DPH [Department of Public Health] by local, state and federal partners that manage or regulate the respective waterbody.”
‘WHEN IN DOUBT, STAY OUT!”
• Harmful algal blooms are the rapid growth of algae or cyanobacteria in water that can harm people, animals, or the environment.
• Going in or near water with a harmful algal bloom can make you and your animals sick.
• Stay out if water looks discolored, has scum, or smells bad.
