Real-Time Updates on Beach Water Conditions

Review the latest water quality reports for Barnstable’s ponds, lakes, and saltwater beaches. Stay informed regarding potential Cyanobacteria or E. coli concerns to ensure safe and enjoyable visits to our various waterbodies.

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Latest Beach Water Quality Updates

July 1, 2025 | Cyanobacteria Updates – Public Health Advisory Issued at Long Pond, Marstons Mills, and Pet Advisory at Crystal Lake, Osterville and Long Pond, Centerville

July 1, 2025 | Cyanobacteria Updates – Public Health Advisory Issued at Long Pond, Marstons Mills, and Pet Advisory at Crystal Lake, Osterville and Long Pond, Centerville

by | Jul 1, 2025 | ,

As of Tuesday, July 1, 2025, at 2:00 PM, the following water quality alerts have been issued: A Public Health Advisory is posted for Long Pond, Marstons Mills due to a significant increase in cyanobacteria levels in samples. A Pet Advisory is posted for Crystal Lake,...

June 24, 2025 | Cyanobacteria Updates – Public Health Advisory Issued at Schoolhouse Pond, Hyannis and Pet Advisories Issued at Various Locations

June 24, 2025 | Cyanobacteria Updates – Public Health Advisory Issued at Schoolhouse Pond, Hyannis and Pet Advisories Issued at Various Locations

by | Jun 24, 2025 | , ,

As of Tuesday, June 24, 2025, at 2:08 PM, the following water quality alerts have been issued A Public Health Advisory has been issued at Schoolhouse Pond, Hyannis due to a significant increase in cyanobacteria levels in samples. A Pet Advisory has been issued...

Water Quality Measurements

Water quality samples measure for a variety of factors that help us determine the health of the freshwater or saltwater ecosystem.

Dissolved Oxygen

A dissolved oxygen (DO) water quality sample measures the amount of gaseous oxygen dissolved in a water body, a crucial indicator of water health. DO is essential for aquatic life, and its levels are influenced by factors like temperature, salinity, and biological activity. Analyzing DO levels helps assess the overall health of an aquatic ecosystem and identify potential pollution sources.

Water Clarity

Water quality in a water sample is assessed by measuring various physical, chemical, and biological parameters. These measurements help determine if the water is safe for its intended use, such as drinking, recreation, or supporting aquatic life. Key indicators include pH, turbidity, dissolved oxygen, temperature, and the presence of bacteria or other contaminants.

Nutrients and/or Bacteria Levels

In a water quality sample, nutrients typically refer to the levels of nitrogen and phosphorus, which are essential for plant and algal growth but can cause problems when present in excess. Public bathing beaches also undergo bacterial testing weekly throughout the summer season, to ensure safe recreational use.

Chlorophyll

Chlorophyll in a water quality sample is primarily used as an indicator of phytoplankton biomass and photosynthetic activity, which in turn can reflect water quality and ecosystem health. Excessive chlorophyll levels can indicate problems like algal blooms and poor water clarity, while low levels might suggest nutrient limitations or other issues.

Salinity

Salinity in a water quality sample refers to the concentration of dissolved salts in the water. It’s a crucial factor in determining water quality and its suitability for various uses, as different organisms and applications require specific salinity levels. Salinity is often measured in parts per thousand (ppt) or parts per million (ppm).

pH / Alkalinity

In water quality analysis, pH and alkalinity are crucial parameters. pH measures the acidity or basicity of water, while alkalinity measures its capacity to neutralize acids. Both are important for understanding water’s chemical characteristics and its impact on aquatic life and human use.

Common Questions About Beach Water Quality

Find answers to your questions about water quality sampling at Barnstable’s ponds, lakes, and saltwater beaches.

How are Barnstable's saltwater embayments monitored?

Our seven (7) embayments – Barnstable Harbor, Centerville Harbor, Halls Creek, Lewis Bay, Popponessett Bay, Rushy Marsh, and Three Bays – are sampled four times annually throughout July and September. A total of 70 sentinel stations are sampled as part of a collaborative effort involving Town staff (DPW, MEA, and Health), Citizen volunteers, Barnstable Clean Water Coalition, Adjacent Towns, and UMass Dartmouth School for Marine Science and Technology (SMAST).

Measurements are taken for dissolved oxygen, water clarity, nutrients (i.e. nitrogen), chlorophyll, and salinity. Ultimately, our Embayment Monitoring Program provides critical baseline data for our estuaries along with the ability to track nitrogen improvements as we implement the CWMP.

How are Barnstable's ponds and lakes monitored?

There are 163 ponds in Barnstable — 27 ponds greater than 10-acres, 17 public and semi-public freshwater beaches, 12 Town Way to Water locations, 6 boat ramps, and 4 ponds stocked with trout.

There are a number of monitoring initiatives to track the health of our freshwater ponds and lakes, including:

  • Ponds and Lakes Snapshot Monitoring (PALS)
  • Cyanobacteria Monitoring
  • Pond and Lake Management Program
  • Rivers and Streams Monitoring and Restoration Projects

Water quality sampling at our freshwater locations looks for excess nutrients, particularly phosphorus, while also testing for low dissolved oxygen, poor water clarity, and algae/cyanobacteria.

What is cyanobacteria?

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.

Barnstable has partnered with the Association to Preserve Cape Cod (APCC), a local non-profit environmental organization, to proactively monitor Cape Cod’s ponds and lakes for cyanobacteria and, more specifically, the toxins they sometimes produce. The monitoring season takes place annually from May through September and is conducted weekly to monthly – the frequency depends on cyanobacteria levels and historic occurrence of blooms.

Click here to visit our Cyanobacteria Monitoring page to learn more.

What is the Pond and Lake Stewardship (PALS) Monitoring Program?

Established in 2002, the Pond and Lake Stewardship (PALS) Monitoring Program, provides an annual ‘snapshot’ of the Cape’s pond and lake water quality. Samples are collected and sent for analysis to the Coastal Systems Program lab at the University of Massachusetts-Dartmouth School for Marine and Technology (SMAST). Sampling is a collaborative effort involving Town staff, citizen volunteers, and the Barnstable Clean Water Coalition.

Water quality samples take measurements for dissolved oxygen, water clarity, nutrients (i.e. nitrogen, phosphorus), chlorophyll, and pH/alkalinity.

~180 water samples are collected annually over our Spring and late-Summer sampling cycle.

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Resources

The Cape Cod Water Quality Data Portal

Cape Cod Commission

2025 Bathing Beach Monitoring Data

Barnstable County

2025 Cyanobacteria Monitoring Map

Association to Preserve Cape Cod

Harmful Algal Blooms and Your Health

Centers for Disease Control