Water Quality FAQs

What are nitrogen and phosphorous and why are they a problem?

Nutrient pollution is one of the Cape’s most widespread, costly and challenging environmental issues, and is caused by excess nitrogen and phosphorus in the water.  Nitrogen and phosphorus are nutrients that are natural parts of aquatic ecosystems.  Nitrogen is also the most abundant element in the air we breathe.  Nitrogen and phosphorus support the growth of algae and aquatic plants, which provide food and habitat for fish, shellfish and smaller organisms that live in water; but, when too much nitrogen and phosphorus enter the environment, the air and water can become polluted. 

Nutrient pollution has impacted the Cape’s rivers, ponds/lakes, bays and coastal waters for decades, resulting in serious health and environmental repercussions that threaten our economy and way of life.  Too much nitrogen and phosphorus in the water causes algae to grow faster than ecosystems can handle.  Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive.  Large growths of algae are called "algal blooms” and they can severely reduce or eliminate oxygen in the water, leading to illnesses in fish and the death of large numbers of fish.  Some algal blooms are harmful to humans because they produce elevated toxins and bacterial growth that can make people sick if they come into contact with polluted water, consume tainted fish or shellfish, or drink contaminated water.

The primary sources of excess nitrogen and phosphorus on Cape Cod are:

• Stormwater:  When precipitation falls on our cities and towns it runs across hard surfaces - like rooftops, sidewalks and roads - and carries pollutants, including nitrogen and phosphorus, into local waterways.
• Wastewater:  Our sewer and septic systems are responsible for treating large quantities of waste, and these systems do not always operate properly or remove enough nitrogen and phosphorus before discharging into waterways.
• In and Around the Home:  Fertilizers, yard and pet waste and certain soaps and detergents contain nitrogen and phosphorus, and can contribute to nutrient pollution if not properly used or disposed. The amount of hard surfaces and type of landscaping can also increase the runoff of nitrogen and phosphorus during wet weather.

Residents can participate in community efforts to improve water quality and make the environment healthier and safer by working in cooperation with local government and other stakeholders in implementing strategies aimed at reducing nutrient pollution.

What is cyanobacteria and when/why is it unsafe to swim in certain areas?

Cyanobacteria, also referred to as blue-green algae, are microscopic organisms that live primarily in fresh water but can also be found in brackish or salt water.

An overgrowth of cyanobacteria is referred to as a “cyanobacterial bloom.” Cyanobacterial blooms are usually blue-green in color, but can be other colors, including red or brown. When a bloom occurs, scum might float on the water surface.  As it decays, it can smell like rotting plants.  Cyanobacterial blooms more often occur during the summer or early fall but can occur anytime during the year.  Cyanobacteria usually multiply and bloom when the water is warm, stagnant, and rich in nutrients (phosphorus and nitrogen) from sources such as fertilizer runoff or septic tank overflows.  If you see a visible scum layer or anything suspicious in the pond water, notify the Board of Health as soon as possible.

Not all cyanobacterial blooms present a threat, but a bloom can be harmful to people, animals, or the environment if it:

• produces toxins,
• becomes too dense,
• uses up the oxygen in the water, or
• releases harmful gases

Common cyanotoxins include: Microcystins, Cylindrospermopsins, Anatoxin-a, Guanitoxin, formerly known as anatoxin-a(S), Saxitoxins, Nodularins, Lyngbyatoxins.  Routes of exposure include:

• Ingestion: swallowing contaminated water or eating food contaminated with toxins (including taking contaminated nutritional supplements)
• Inhalation:  breathing in aerosolized toxins
• Skin contact:  direct contact with contaminated water during activities like swimming or boating
• Eye contact:  direct contact with contaminated water or aerosols

Many factors determine whether exposure to cyanobacterial blooms will cause adverse health effects. These factors include, but are not limited to: toxin type and concentration, duration and route of exposure, and any comorbid conditions of the patient (more than one disease or condition is present in the same person at the same time).

Some commonly reported symptoms following specific toxin exposures include:

• Microcystins: abdominal pain, nausea, vomiting, headache, diarrhea, sore throat, blistering around the mouth, and pneumonia.
• Cylindrospermopsin: gastrointestinal symptoms, including vomiting and bloody diarrhea, as well as fever and headache.
• Anatoxin-a: neurologic symptoms, including numbness, tingling, burning sensation, drowsiness, salivation, and speech disturbances.

Cyanobacteria monitoring efforts on Cape Cod

How frequently are the bathing beaches sampled?

The Barnstable County Department of Health and Environment provided the summer bathing beach sampling labor and administrative reporting to the Town and state.  Samples are taken on a weekly basis.  Additionally, the Mashpee Department of Natural Resources monitors all fresh and marine water bodies.  Should there be a need for an advisory or closure, the beach is posted with signage and notice is posted on the Town website and reported to MA DPH.