The Town of Nantucket, in collaboration with Nantucket Land Council, Nantucket Conservation Foundation, Nantucket Land Bank, Linda Loring Nature Foundation, UMASS Boston, and Mass Audubon monitors the following ponds for harmful algal blooms (HABs) weekly from June 2nd through October 3rd:

• Long
• North Head of Long
• Miacomet
• Sesachacha
• Capaum
• Gibbs
• Hummock
• Clark’s Cove (West Hummock Pond)
• Maxcy
• Washing
• Tom Nevers
• Stump
• Almanac
• Wigwam
• Pout
• and UMASS Boston’s Nantucket Field Station (NFS) Ponds.**

As part of the Massachusetts Department of Public Health Bathing Beach Testing Program, the Town of Nantucket tests public beaches weekly during the warmer months to ensure bacteria-related water quality requirements are being met. This testing is different from toxic algae as it focuses on bacteria levels, thus sometimes posing an issue with conflicting Town signage. If the Health Department sign indicates water is safe for swimming but the water looks green, please use caution when recreating as potential toxins may be present even when bacterial levels are considered safe for swimming.

Want to know more about HABs?

• Read the FAQs!

How to report a HAB:

• Click HERE to send your report.
• Haz clic AQUÍ.

Adopt a Pond Program
Want to help expand our capacity to monitor all waterways on Nantucket? By “Adopting a Pond,” you can help us monitor water conditions by visiting https://www.nantucketbiodiversity.org/pondsurvey and downloading the Nantucket Pond Water Guide. Please contact our Water Quality Specialist Emma Morgan at emorgan@nantucket-ma.gov for more information on volunteering to monitor our ponds.

Disclaimer
The Nantucket HAB monitoring team collects samples and conducts visual inspections at the abovementioned ponds to determine the presence or absence of potentially toxic algae. The duration of a HAB occurrence is dependent on several factors, including physical and biological conditions, and therefore is not possible to predict in advance. As monitoring is performed weekly and at specific locations and times, blooms may occur and disappear throughout the week. Not all algal blooms are harmful, and it is impossible to determine if a bloom is harmful just by looking at it. If you are unsure whether a bloom is harmful or not, please keep away from the pond. Never recreate in a pond that is experiencing an active HAB. For more information, please visit the Environmental Protection Agency website at https://www.epa.gov/cyanohabs.