Cyanobacteria Monitoring
Cyanobacteria monitoring for the 2025 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
October 14, 2025 | Pet Advisories to be Removed at Aunt Betty’s Pond, Hyannis and Round Pond, Marstons Mills
As of Tuesday, October 14, 2025, the following water quality updates have been issued: A Pet Advisory posted for Round Pond, Marstons Mills will be removed due to acceptable water quality samples. A Pet Advisory posted for Aunt Betty's Pond, Hyannis will be...
September 30, 2025 | Pet Advisories to be Removed at Crystal Lake, Osterville and Hinckley Pond, Barnstable
As of Tuesday, September 30, 2025, the following water quality updates have been issued: A Pet Advisory posted for Crystal Lake, Osterville will be removed due to acceptable water quality samples. A Pet Advisory posted for Hinckley Pond, Barnstable will be removed due...
September 26, 2025 | Pet Advisory at Hamblin Pond, Marstons Mills Removed
As of Friday, September 26, 2025, the following water quality updates have been issued: A Pet Advisory posted for Hamblin Pond, Marstons Mills will be removed due to acceptable water quality samples. Current postings as of Friday, September 26, 2025: Current Public...
September 23, 2025 | Pet Advisories Issued for Round Pond, Marstons Mills and Crystal Lake, Osterville
As of Tuesday, September 23, 2025, the following water quality updates have been issued: A Pet Advisory is issued for Round Pond, Marstons Mills, due to increased levels of cyanobacteria in water quality samples. A Pet Advisory is issued for Crystal Lake, Osterville,...
September 19, 2025 | Pet Advisories Issued for Hamblin Pond, Marstons Mills and Aunt Betty’s Pond, Hyannis
As of Friday, September 19, 2025, 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 Aunt Betty's Pond,...
Protecting Barnstable’s Ponds & Lakes: What You Need to Know About the Fertilizer Use Ordinance
In Barnstable, many of us take pride in our homes and lawns. A lush, green yard can feel like part of the Cape Cod dream. But did you know that when you fertilize your lawn, you’re not just feeding your grass—you could also be feeding our ponds and lakes? And...
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.