Cyanobacteria Monitoring
Cyanobacteria monitoring for the 2026 season is underway. Should a Town waterbody fail to achieve an acceptable result, advisories will be posted below via a Town of Barnstable Water Quality Report as well as shared on the MyBarnstable mobile app, via Town social media, and physcially posted at the waterbody site.
Latest Cyanobacteria Advisories
September 1, 2026 | Pet Advisory Posted for Shubael Pond (Marstons Mills) and Garretts Pond (West Barnstable)
As of Tuesday, September 1, 2026, the following water quality updates have been issued: A Pet Advisory will be posted at Shubael pond, Marstons Mills due to increased levels of Cyanobacteria in samples. A Pet Advisory will be posted at Garretts Pond, West Barnstable,...
August 25, 2025 | Pet Advisory Posted for Hinckley Pond, Barnstable
As of Tuesday, August 25, 2026, the following water quality updates have been issued: A Pet Advisory is now in effect at Hinckley Pond, Barnstable due to increased levels of Cyanobacteria in samples. Current postings as of Tuesday, August 25, 2026: Current Pet...
August 18, 2026 | Pet Advisories issued for Long Pond (Marstons Mills) and Fawcetts Pond (Hyannis)
As of Tuesday, August 18 2026, the following water quality updates have been issued: A Pet Advisory will be posted at Long Pond, Marstons Mills due to increased levels of Cyanobacteria in samples. A Pet Advisory will be posted at Fawcetts Pond, Hyannis due to...
August 5, 2026 | Pet Advisory Removed from Long Pond, Marstons Mills
As of Wednesday, August 5, 2026, the following water quality updates have been issued: A Pet Advisory is removed for Long Pond, Marstons Mills, due to acceptable levels of cyanobacteria in water quality samples Current postings as of Wednesday, August 5, 2026: Current...
July 28, 2026 | Pet Advisory Removed from Hamblin Pond (Marstons Mills), Shubael Pond (Marstons Mills), Hinckley Pond (Barnstable)
As of Tuesday, July 28, 2026, the following water quality updates have been issued: A Pet Advisory is removed for Hamblin Pond, Marstons Mills, due to acceptable levels of cyanobacteria in water quality samples A Pet Advisory is removed for Shubael Pond, Marstons...
July 21, 2026 | Pet Advisories Issued for Hamblin Pond, Long Pond, and Shubael Pond (Marstons Mills); Lovells Pond (Cotuit)
As of Tuesday, July 21, 2026, the following water quality updates have been issued: A Pet Advisory is issued for Hamblin Pond, Marstons Mills, due to increased levels of cyanobacteria in water quality samples A Pet Advisory is issued for Long Pond, Marstons Mills, due...
Cyanobacteria Monitoring Map
Barnstable County has partnered with the Association to Preserve Cape Cod (APCC), a local non-profit environmental organization, to proactively monitor Cape Cod’s ponds for cyanobacteria and, more specifically, the toxins they sometimes produce. For more specifics regarding the particulars of the monitoring program, please visit APCC’s cyanobacteria monitoring web page.
CYANOBACTERIA MONITORING IN THE TOWN OF BARNSTABLE
Understanding the Problem
Cyanobacteria are microscopic bacteria that live in all types of waterbodies. A large growth of these bacteria results in algal blooms. These blooms can pollute the water and may even be toxic to animals and people.
When a dramatic increase in a cyanobacteria population occurs, this is called harmful algal blooms (HABs). This often results in the waterbody turning bright green or blue-green, and forms a surface scum or a discoloration of the water column. CyanoHABs may also form a mat on the bottom sediments, making it more difficult to observe. The surface scums or discolored waters can extend several inches below the water surface, or accumulate near shorelines and in coves as a result of onshore wind activity. They often look like pea soup or spilled, blue or green paint; however, the color can also vary. CyanoHABs can cause dissolved oxygen swings that may result in plant and animal die-off, taste and odor issues, and can cause potential public health issues from the cyanotoxins they may release.
Cyanobacteria on Cape Cod
Typically, cyanobacteria’s potential for overgrowth is kept in check by a balance of several different factors, one of which is nutrient availability. All animals and plants require nutrients to grow and thrive, but if an external force makes nutrients either scarce or overabundant, the balance is disrupted. Here on Cape Cod, human activities – from fertilization to faulty septic systems – have introduced an overabundance of nutrients into the environment, which leads to an ecologically unhealthy condition called eutrophication (the process by which a water body becomes enriched in dissolved nutrients such as phosphates and nitrogen). The greater the nutrient availability, the more fuel for cyanobacteria (and other undesirable plant life) to grow and thrive. Global warming also plays a key role with warmer pond temperatures favoring cyanobacteria. Learn more about cyanobacteria monitoring across Cape Cod through Barnstable County’s efforts.
UNDERSTANDING CYANOBACTERIA ADVISORY ICONS
Protect Yourself and Your Pets
Algae Contact
If you have any contact with water, rinse off immediately.
Do Not Drink
Do not swallow water. Do not use water for cooking. Boiling or filtering will not make it safe.
Children
Keep children away from algae in the water or on the shore.
Stay Out
Stay out of the water until further notice. Do not touch scum in the water or on shore.
Pets
Do not let pets go into or drink the water or eat scum.
Shellfish
Do not consume shellfish harvested from this water.
Swimming
No swimming when blooms are present.
Fishing
Throw away guts, clean fillets with tap or bottled water before cooking.