Clean water is central to the health of the Cape’s natural ecosystems. Our coastal waters, estuaries, and embayments support valuable shellfish such as oysters and clams, as well as important finfish such as winter flounder and striped bass. Waterbirds, migrating waterfowl, raptors and wildlife feed on fish, shellfish and aquatic plants. Freshwater ponds and streams support numerous fish and wildlife species, including important diadromous species such as river herring and American eels which live in both fresh water and the ocean. The Cape’s ecosystems and food web depend upon clean water.

Clean water is also important for our economy. The Cape’s economy is a “blue economy” where our residents, visitors and businesses rely upon clean water and healthy natural resources. The economic benefits of clean water and healthy ecosystems are demonstrated by the fact that coastal tourism and commercial and recreational fishing and shellfishing and their supporting industries bring in more than $1 billion to the local economy. For example, in 2017 tourists visiting Cape Cod spent $1.1 billion that supported 10,300 tourism-related jobs and $317.5 million in wages and generated $122 million in state and local taxes (Cape Cod Chamber of Commerce).

Commercial and recreational fishing and shellfishing also bring in additional millions of dollars each year. For example, from 2000 – 2004, the average annual value of commercial and recreational shellfishing was $11.4 million. In 2009 alone the value of commercial fishing was $19 million, while the value of commercial fishing for species that eat river herring was over $37 million (NRCS, Cape Cod Water Resources Restoration Project, Why It Matters to Massachusetts Economy). These numbers do not include water-focused organizations such as oceanographic institutions and businesses, non-governmental organizations, educational institutions and laboratories which employ people and provide services and products.

Finally, clean drinking water is critically important for our health. The water we drink comes from Cape Cod’s sole-source aquifer, a vast underground natural reservoir of groundwater. Federal, state and local laws are designed to protect a sole-source aquifer from pollution. However, as we discuss below, our groundwater, ponds, lakes, estuaries and embayments are all interconnected.


Cape Cod enjoys a wealth of water resources. These include salt water and fresh water resources. Each major resource is summarized below. More information can be obtained at the Cape Cod Commission’s website on water resources.

Coastal waters (saltwater) surround most of the Cape, creating over 559 miles of coastline bordering the Atlantic Ocean, Nantucket Sound, Vineyard Sound, Buzzards Bay, and Cape Cod Bay. This long coastline contains 53 distinct saltwater embayments, places where there is a recess or indentation in the coastline that forms a bay bordering the ocean. Estuaries are places where rivers meet the sea. Estuaries typically contain a range of wetlands including freshwater, brackish and tidal wetlands (aka salt marshes) and tidal channels. On Cape Cod, rivers, streams and groundwater flow into estuaries and embayments which border the ocean.

Freshwater ponds and lakes: Few people know that the Cape is the land of (nearly) a thousand lakes. At least 996 freshwater ponds and lakes cover nearly 11,000 acres and individual ponds and lakes range in area from less than one acre to 735 acres and include 166 “great ponds” of 10 acres or greater in size. Because the Cape’s ponds and lakes are fed by groundwater, they are often referred to as “windows on our aquifer”. The sandy soils of the Cape allow groundwater to flow into and out of ponds. For this reason, pollution of ponds will likely also pollute groundwater, and vice versa.

Groundwater: Groundwater is the lifeblood of the Cape. Rain and melting snow quickly soak into our sandy soils where it collects to form a huge underground reservoir of groundwater that lies beneath most of the Cape. Water seeks the lowest elevation, so groundwater continues to move, seeking sea level, flowing into and out of ponds, feeding streams and flowing towards the coast, finding sea level when it enters our estuaries and embayments.

Groundwater is also the sole source of our drinking water and for that reason it is designated as Cape Cod’s sole-source aquifer. Most public water suppliers use groundwater wells for drinking water. Even the Cape’s only surface water source (Long Pond in Falmouth) is fed by groundwater. Cape Cod’s groundwater has been designated by the U.S. EPA as a sole-source drinking water aquifer to be protected from pollution.

Watersheds connect our waters: Nearly all of the Cape’s waters are connected by watersheds that collect water and discharge it into the ocean. Watersheds are the land areas that collect rain and snow which drains into ponds, lakes, streams, and groundwater, which in turn discharge into estuaries, embayments and the ocean. Cape Cod has a total of 101 watersheds that discharge to the ocean. Of these, 53 discharge to embayments which are susceptible to nitrogen pollution, and the remainder discharge directly to the ocean. The Cape Cod Commission has developed descriptions of the Cape’s watersheds and what is being done to protect and improve water quality.

Hydrological cycle: The Cape receives about 45 inches per year of rain and melting snow. About 60 per cent of this precipitation soaks into the ground to replenish groundwater. Most of the remaining 40 per cent evaporates into the atmosphere where it provides moisture for storms that provide rain and snow (see below). A small amount runs off as stormwater runoff along the surface of the land (aka stormwater runoff). Due to the sandy soils, this runoff generally soaks into the sand and replenishes the aquifer. However, when runoff flows from roads, parking areas and fertilized lawns directly into wetlands or water, pollutants from these developed areas can enter the water. Stormwater pollutants can include fertilizers, bacteria, soil particles, metals, and de-icing compounds.

Groundwater is used up (depleted) when we withdraw it for drinking water and when it flows into ponds, streams, embayments and into the ocean. Ponds, streams and wetlands lose water due to evaporation, and trees also “breathe” water back into the air in a process called “evapotranspiration”. All of this evaporated water is not truly “lost”; instead it is critically important for feeding water back into the atmosphere to grow storms that produce rain and snow. Groundwater is replenished by rain and melting snow which soak into the ground, beginning the hydrological cycle all over again.


Most of the Cape’s coastal embayments and many freshwater ponds and lakes are suffering from water pollution, based on years of studies and reports on water quality and water pollution. These studies and reports indicate that the Cape’s waters suffer from pollution due to the following pollutants and pollution sources.

Nutrient pollution: Excess nutrients (nitrogen in coastal waters and phosphorus in fresh water) have caused severe eutrophication and severe ecological damage. Eutrophication refers to the harmful effects of excess nutrients on an aquatic ecosystem, resulting in increased growth of phytoplankton and depletion of oxygen. Excess nutrients in water stimulates the growth of phytoplankton (microscopic algae), which depletes the water of oxygen. Oxygen depletion leads to fish kills and impacts on shellfish and other aquatic life. Excess phytoplankton also causes water to become cloudy, reducing the amount of light in the water column, which impacts the growth of other beneficial aquatic plants such as eelgrass. When algae die their remains settle to the bottom and decompose, causing more oxygen depletion and releasing nutrients back into the water, feeding the nutrient cycle. Also, the buildup of decaying organic matter on the bottom of ponds, lakes, and embayments often results in thick muck that is unhealthy for shellfish, fish and other aquatic organisms.

Many of the Cape’s estuaries and embayments are suffering from eutrophication caused by excess nitrogen, as demonstrated by the Massachusetts Estuaries Project and by the 208 Water Quality Management Plan for Cape Cod.

Ponds and lakes are also suffering from eutrophication caused by excess phosphorus (Cape Cod Commission, Ponds and Lakes website).

On Cape Cod, excess nutrients originate largely from human sources and activities. Excess nitrogen comes from poorly treated wastewater (e.g., Title 5 septic systems) as well as fertilizers used on lawns, gardens, golf courses and farms. Some nitrogen also falls out from the atmosphere in precipitation, and this atmospheric nitrogen largely originates from burning fossil fuels. Excess phosphorus comes from septic systems that discharge phosphorus into groundwater that enters ponds and lakes, as well as fertilizers used on lawns, gardens, golf courses and farms which is carried into ponds and lakes in stormwater runoff.

Harmful bacteria include bacteria that originate from fecal wastes (humans and/or animals). Examples of fecal bacteria are Escherichia coli (E. coli), and enteric bacteria. Fecal bacteria can cause illness in both humans and animals. On Cape Cod, most fecal bacteria contamination originates from domestic animals and wildlife. Failed septic systems (including flooded septic systems) are another source of bacteria. Bacteria are carried into water by stormwater runoff. State and federal water quality standards limit the amount of fecal bacteria that can be present in waters where swimming and shellfishing are conducted. Swimming beach water quality is monitored by Barnstable County. The Massachusetts Division of Marine Fisheries monitors water quality in shellfish beds and limits shellfishing to waters that meet a stringent water quality standard for fecal bacteria.

Harmful algal blooms include toxic red tides in coastal waters and toxic cyanobacteria blooms in freshwater ponds and lakes. Red tide is the common name for several species of phytoplankton, including toxic dinoflagellates. Shellfish that ingest such toxic phytoplankton become toxic themselves, posing a threat to humans who eat contaminated shellfish and impacting the shellfishing industry. In fresh water, toxic cyanobacteria thrive in nutrient-rich and warm waters. APCC’s cyanobacteria monitoring program has documented cyanobacteria blooms in dozens of ponds throughout the Cape, and we anticipate this will be an increasing problem as the climate warms.

Mercury pollution occurs in waters throughout the Northeast. On the Cape the Massachusetts Department of Public Health has listed at least 24 ponds and lakes where there are fish consumption advisories that warn people (pregnant mothers) to limit or avoid eating fish from that lake due to mercury pollution. Mercury pollution is caused by fallout of mercury from the atmosphere, which originates from combustion of coal in coal-burning fuel plants. Incineration of medical wastes and municipal wastes also contributes mercury to the atmosphere.

Emerging contaminants and pharmaceutical compounds have been found in groundwater near septic systems and in coastal waters of the Cape. This group of pollutants contains a wide variety of compounds including endocrine-disrupting compounds, pharmaceutical drugs (including antibiotics), insect repellant, flame retardant, fluorinated compounds, and PFAS Silent Spring Institute has been monitoring the Cape’s waters. The Center for Coastal Studies and Silent Spring Institute also found pharmaceutical compounds were also found in Cape Cod Bay and in groundwater near septic systems.

PFAS (per- and poly-fluoroacetate substances) are manmade chemicals used widely in diverse items (e.g., fireproof clothing, non-stick pans, stain-and-waterproof fabrics, fire-fighting foam, dental floss, cleaning products, paints, electronics manufacturing, and other industries and household products). PFAS are long-lasting compounds that have been found worldwide in humans, wildlife, water, soil, and the air. They have been linked to human health impacts such as developmental disorders, immune system disorders, thyroid hormone disruption, and cancer Information on PFAS can be found at EPA and the Commonwealth of Massachusetts.

Aeriel photo of Cape Cod pond
Photography by Steven Koppel


To help people understand where water quality is acceptable vs. unacceptable, APCC has created this project and website to collect existing information on water quality and translate it into easily understood terms by grading water quality. This website is a key means of collecting and distributing information to the public. In doing so, we hope to guide public policy and investment in restoration efforts.

Using existing data, APCC graded the following water resources:

  • Coastal waters in embayments and estuaries,
  • Freshwater ponds and lakes, and
  • Public water supplies for drinking water (i.e., drinking water after it is treated by the public water supplier and before it is distributed to consumers).

APCC used three grading systems, one system for grading coastal waters, a second system for grading ponds and lakes, and a third system for grading drinking water. Each of the grading systems scores water quality parameters, and the scores were then translated into grades. APCC chose grading systems that meet the following criteria:

  • Are scientifically sound;
  • Have been used before to evaluate water quality;
  • Use key water quality parameters to evaluate water quality problems;
  • Are easily understood and can be replicated by others (e.g., it does not require complex methods, modeling or software); and
  • Evaluates the most pressing water quality problems.

The grading systems are explained below.

Grading coastal waters: the Buzzards Bay Eutrophic Index

APCC chose an existing method of grading the severity of nitrogen pollution of coastal waters. The method is called the Buzzards Bay Eutrophic Index (aka “Bay Health Index”), developed in 1992 by the Buzzards Bay National Estuary Program The Eutrophic Index was based on an earlier method developed by Hillsborough County, Florida, to evaluate coastal water quality.

The Buzzards Bay Eutrophic Index was developed to help the Buzzards Bay Coalition (BBC) evaluate citizen water quality monitoring data for Buzzards Bay embayments and to help rank each embayment with respect to its relative health for the purpose of prioritizing remedial management measures ). The goal was to evaluate nitrogen loading inputs and to provide accurate and reliable water quality data for most of the major embayments around Buzzards Bay to assist environmental managers to:

  • Establish baseline water quality;
  • Characterize and identify sources of pollution;
  • Document long-term environmental trends in water quality;
  • Evaluate the relative success of cleanup efforts;
  • Facilitate implementation of management efforts in the CCMP, and
  • Evaluate the appropriateness of the Buzzards Bay Project’s recommended nitrogen limits.

Since then, the Eutrophic Index has been used by the Buzzards Bay Coalition, the Center for Coastal Studies, the Pleasant Bay Alliance, and the town of Chatham to evaluate nitrogen pollution in Buzzards Bay, Cape Cod Bay and coastal waters around the Cape, Pleasant Bay, and Chatham, and is considered by practitioners to be a well-tested method.

The Eutrophic Index scores parameters that measure the degree of eutrophication: dissolved oxygen saturation, water clarity (measured using either Secchi disk or a turbidity meter), chlorophyll, dissolved inorganic nitrogen (DIN), and total organic nitrogen (TON). Water quality data for these parameters is used to calculate a numerical score that indicates the degree of eutrophication. To translate scores into an assessment of water quality, the BBC uses three categories to “grade” scores: scores of 65 to 100 indicate Good water quality; scores between 35 and 65 indicated Fair water quality; and scores below 35 indicate Poor water quality.

Following the BBC’s method, APCC calculated numerical Eutrophic Index scores for water quality from stations in coastal embayments and coastal waters around Cape Cod. However, APCC “graded” the numerical scores in a manner that differs from the BBC. APCC assigned scores to two categories based on whether they indicate acceptable water quality or unacceptable water quality. The two grading categories were chosen to indicate the type of action needed to protect or restore water quality:

Scores greater than 65 are graded as: Acceptable: requires ongoing protection;
Scores of 65 and below are graded as: Unacceptable: needs immediate restoration.

Waters that are graded as “Acceptable: requires ongoing protection” are waters that are healthy and free of excess nutrients. These waters need ongoing protection to remain healthy and free of pollution.

Waters that are graded as “Unacceptable: requires immediate restoration” are waters that are suffering from excess nutrients. These waters need immediate restoration in order to improve water quality.

APCC also took the additional step of identifying embayments where at least one monitoring station had Unacceptable water quality and graded these embayments as “Unacceptable: requires immediate restoration”. Embayments where all monitoring stations had Acceptable water quality were graded as “Acceptable: requires ongoing protection”. This approach provides a clear summary of which embayments have portions with poor water quality that requires restoration vs. embayments with good water quality which requires protection.

Grading freshwater ponds and lakes: the Carlson Trophic Index

To grade freshwater ponds and lakes, APCC chose a scoring method that evaluates the trophic state of the water body in terms of nutrients, chlorophyll and water transparency. The Carlson Trophic Index was developed in 1996 to assess the trophic state of a freshwater pond or lake, where trophic state refers to the ecological response (algal biomass) to nutrients (Carlson, 1977).

Embayments and estuaries often contain aquatic habitats that range from freshwater to brackish to salt marsh to open water bays bordering the ocean. For coastal embayments that contain salt marshes, the Buzzards Bay Coalition developed a variation of their scoring system. APCC’s scoring of salt marsh systems follows the approach used by the Buzzards Bay Coalition. There is disagreement among practitioners in the field about the best system for characterizing salt marsh quality. APCC’s scoring of embayments and estuaries with salt marshes follows the method developed by the Buzzards Bay Coalition, with modifications suggested by Dr. Brian Howes of SMAST, University of Massachusetts-Dartmouth.

Using the Carlson Trophic Index, a pond with high nutrient concentrations (eutrophic to hypereutrophic) would be characterized by high concentrations of algae, algal scums, poor water clarity due to dense algae, and low to no dissolved oxygen. A eutrophic to hypereutrophic pond would have scores from 50 to 100. At the opposite end of the spectrum, a pond with low nutrient concentrations (oligotrophic) would be characterized by clear well-oxygenated water, healthy aquatic plants, and little to no algal growth. An oligotrophic pond would have scores from 0 to 40. A pond with intermediate nutrient concentrations (mesotrophic) would be characterized by moderately clear water, intermediate amounts of aquatic plants and algae, and low dissolved oxygen during the summer. A mesotrophic pond would have scores from 40 to 50. The Carlson Trophic Index is analogous to the Buzzards Bay Eutrophic Index in that it can be used to evaluate the degree of eutrophication in fresh water.

APCC adopted a grading system that assigns the following grades to Carlson Trophic Index scores:

Scores of less than 50 are graded as: Acceptable: requires ongoing protection;
Scores of 50 and above are graded as: Unacceptable: needs immediate restoration.

Waters that are graded as “Acceptable: requires ongoing protection” are waters that are healthy and free of excess nutrients. These waters need ongoing protection to remain healthy and free of pollution.

Waters that are graded as “Unacceptable: requires immediate restoration” are waters that are suffering from excess nutrients. These waters need immediate restoration in order to improve water quality.

Grading public water supplies of drinking water

The grading system for drinking water uses a method developed by the Natural Resources Defense Council (NRDC) to grade drinking water. The NRDC grading system evaluates three areas of drinking water: water quality and compliance, source water protection, and right-to-know compliance. APCC chose to evaluate water quality and compliance of public water supplies after treatment and before distribution to consumers, the so-called “finished water”. This represents the underlying quality of the public water supply before it is distributed to customers, not the quality of the water as it comes out of your tap which can be affected by pipes and plumbing in the distribution system and your homes and businesses. APCC chose to evaluate public water supplies in this manner because underlying water quality represents the first line of defense in ensuring safe drinking water supplies and because many water protection measures are aimed at protecting source water quality.


Cape Cod is fortunate to have many environmental organizations and agencies which have monitored water quality for many years. Over the years, hundreds of citizen scientists, local, state and federal government agencies, scientists, environmental organizations, consulting firms, and APCC interns and volunteers have collected water samples for different water quality monitoring programs. With the assistance of our Advisory Committee and partners, our sources of water quality data include the following:

  • Barnstable Clean Water Coalition: Three Bays coastal water quality data, pond water quality data;
  • Buzzards Bay Coalition: Eutrophic Index scores for Buzzards Bay coastal stations;
  • Cape Cod Commission and University of Massachusetts at Dartmouth, School of Marine and Atmospheric Science and Technology (SMAST): PALS data for pond water quality;
  • Cape Cod Commission: Center for Coastal Studies coastal water quality data collected as part of an EPA-funded program to collect and make available all water quality monitoring data for the Cape;
  • Center for Coastal Studies: coastal water quality data collected by the Center’s coastal monitoring program;
  • Pleasant Bay Alliance: Eutrophic Index scores for Pleasant Bay coastal stations;
  • Town of Eastham, Massachusetts: coastal water quality data from SMAST, PALS pond water quality data;
  • Town of Chatham, Massachusetts: coastal water quality data, Eutrophic Index scores for Chatham coastal stations;
  • Waquoit Bay National Estuarine Research Reserve (WBNERR): coastal water quality data for Waquoit Bay.

Types of water quality data are summarized below.

Water quality data for coastal embayments: For the 2020 report, APCC collected coastal water quality data from seven different sources: Center for Coastal Studies, Buzzards Bay Coalition, Barnstable Clean Water Coalition, Town of Chatham, Town of Eastham, Pleasant Bay Alliance, and Cape Cod Commission.

Water quality data for ponds and lakes: Since 2000 the Cape Cod Pond and Lake Stewardship program (PALS) has worked with volunteers and organizations who monitor many ponds across the Cape. The PALS program was developed by the Cape Cod Commission, APCC, and SMAST, in coordination with organizations and towns that monitor water quality on an annual snapshot basis. Other pond associations and organizations have gathered a considerable amount of data with their member volunteers. For the 2020 report, APCC collected PALS pond water quality data collected by SMAST (provided by the Cape Cod Commission), Barnstable Clean Water Coalition, and Town of Eastham (See the Data / Ponds for the PALS database used in this assessment).

Water quality data for public water supplies: For the 2020 report, APCC collected each town’s public-right-to-know reports, also known as the Consumer Confidence Reports (CCRs) for drinking water. CCRs were used to grade water quality and compliance with existing drinking water regulations. CCRs are posted on each town’s website.


Our scores and grades for coastal stations, coastal embayments, ponds and lakes, and public water supplies are provided as read-only spreadsheets and as maps: Embayment StatusEmbayment Station StatusPond StatusPublic Water Supply Status.


More than two-thirds of coastal embayments and more than one-third of ponds are suffering from unacceptable water quality due to excess nutrients. As most of the Cape is served by Title 5 septic systems and only small areas are served by publicly-owned wastewater treatment facilities, the main cause of unacceptable water quality in both coastal embayments and fresh water ponds is excess nutrients due to inadequately treated wastewater, followed by poorly treated stormwater runoff and fertilizers.

More water quality monitoring data are needed for most ponds. Only 149 (15 percent) of the 996 ponds and lakes on Cape Cod are monitored for water quality. APCC’s Cyanobacteria Monitoring Program has been monitoring 30+ ponds and lakes for harmful cyanobacteria blooms, and most of these ponds have experienced cyanobacteria blooms this summer. Harmful cyanobacteria blooms occur in ponds when there are excess nutrients and warm temperatures, conditions which are likely to occur more frequently as climate change continues.

In contrast, 20 public water supplies in 15 towns across the Cape were all graded as excellent based on existing drinking water quality standards. However, emerging contaminants are of concern and need to be monitored. It is important to note that for most of these contaminants, no drinking water standards have been established. Examples include PFAS, endocrine-disrupting compounds, pharmaceuticals, and microplastics.

Detailed findings:


  • Of the 48 embayments for which data were available, more than two-thirds (33 embayments or 69%) had Unacceptable water quality in at least a portion of the embayment and less than one-third (15 embayments or 31%) had Acceptable water quality.
  • Most of the embayments with Unacceptable water quality in at least a portion of the embayment are located along the western, southern and eastern coasts of Cape Cod. These are generally areas where the watershed contains densely developed areas served by Title 5 septic systems and where embayments have low flushing rates.
  • Most of the embayments with Acceptable water quality are located on Cape Cod Bay (a few are located on Buzzards Bay). These are generally areas where the population density is lower resulting in relatively fewer septic systems, and there is relatively more protected open space. Also, Cape Cod Bay has a greater tidal range (e.g., 13+ feet) than Buzzards Bay (e.g., 6+ feet) or Nantucket Sound (e.g., 5+ feet) . Greater tidal range enables more tidal flushing which means that seawater flows into and out of embayments more quickly. If pollutants are present, they will be dispersed more quickly.

Embayment stations (these are monitoring stations where water quality monitoring data were available):

  • Of the 152 embayment stations which were scored, nearly two-thirds (98 stations or 64%) had Unacceptable water quality and over one-third (54 stations or 36%) had Acceptable water quality.
  • In most embayments with more than one monitoring station, the stations closest to land often had lower scores (worse water quality) than stations further out to sea which tended to have higher scores (better water quality).

Ponds and lakes:

  • Of the 996 ponds on Cape Cod, PALS monitoring data were available for only 15% of ponds (149 ponds). Of these 149 monitored ponds, over one-third (58 ponds or 39%) had Unacceptable water quality and less than two-thirds (91 ponds or 61%) had Acceptable water quality.
  • Ponds with Unacceptable water quality included both large and small ponds.
  • Unacceptable pond grades reflect the impact of excess nutrients (phosphorus) from septic systems, fertilized lawns, and stormwater runoff.

Public water supplies (this does not include private wells):

  • Drinking water grades for 20 public water supplies were Excellent, based on published Consumer Confidence Reports. These grades indicate that drinking water sources meet existing drinking water standards and that source water protection methods (e.g., wellhead area protection, watershed protection, open space protection) are working to protect water quality in terms of regulated contaminants.
  • Consumer tap water quality was not evaluated and would require testing of the water coming out of consumers’ taps as well as monitoring data from water distribution systems. Water quality coming out of the tap will be affected by the age and type of pipes in the distribution system and in consumers’ homes and businesses.
  • Drinking water consumers and regulators alike need to consider that there may be other unregulated contaminants affecting drinking water quality. These include:
    • PFAS in drinking water and in aquatic ecosystems, from a wide variety of sources;
    • Emerging contaminants in surface water and/or groundwater:
      • Endocrine-disrupting compounds and pharmaceuticals from inadequately treated wastewater
      • Microplastics from wastewater, stormwater runoff, and atmospheric fallout;
      • Cyanobacteria (aka blue-green algae) in freshwater ponds produce toxins that are harmful to humans and animals if ingested. Public water supplies can be contaminated by cyanotoxins, and public water suppliers elsewhere are taking precautions to guard against cyanotoxins in drinking water. APCC has been monitoring cyanobacteria since 2017 and next year we anticipate that cyanobacteria will be added to the grading system for ponds and drinking water.

Other issues of concern for water quality:

  • Harmful bacteria in coastal waters and freshwater ponds, lakes and streams. These include fecal coliform bacteria and enteric bacteria that are indicators of human and/or wildlife fecal matter. Bacteria can impact swimming beach water quality and water quality in shellfish beds. Beach water quality and shellfish bed water quality are monitored by the County and state, respectively.
  • Mercury contamination of surface water is of concern, based on the fact that 24 ponds and lakes on the Cape have fish consumption advisories due to the high levels of mercury. Mercury originates from atmospheric fallout of mercury emissions from fossil-fuel-burning power plants.
  • Climate change is paramount. Climate change predictions for the Northeast include warmer air and water temperatures year-round; more precipitation; more intense storms; longer and warmer growing seasons coupled with shorter and warmer winters; shifts in populations of fish, wildlife and invertebrates; rising sea level; changes in groundwater elevations; more flooding; and changes in dynamic landforms such as those found on the Cape (e.g., dunes, beaches, floodplains). Many of these climate change predictions will impact water quality and exacerbate the harmful effects of existing pollutants.

“Filling the Gaps” – Recommendations for monitoring:

  • Monitoring of at least five more coastal embayments is needed (Chase Garden Creek in Yarmouth, Red River in Harwich, Hatches Harbor in Provincetown, and Little Pond and Great Sippewissett Marsh in Falmouth). These embayments are listed in the 208 Water Quality Plan as coastal embayments receiving nutrients from their watersheds;
  • Only 15 percent of the 996 ponds and lakes on the Cape are being monitored through the PALS program. This means that water quality in 85 percent of ponds is unknown. Pond monitoring should be expanded to many more ponds and lakes throughout the Cape, particularly those where there is public access or where sensitive living resources (e.g., diadromous fish, rare species, wildlife) are located. Pond monitoring should be conducted more frequently than the once-a-year snapshot that is typically provided by the PALS program.
  • The PALS program is useful as a “screening tool” to identify ponds where more in-depth monitoring and assessment is needed to determine extent and severity of problems.
  • Monitoring of pond water quality and cyanobacteria blooms should be coordinated so that water quality data can be used to help predict where serious cyanobacteria blooms may occur.
  • Public water suppliers should expand their monitoring of PFAS, emerging contaminants and cyanobacteria to help safeguard public health.
  • See the Water Action Plan for more recommendations.


Click on a map image below to open the corresponding PDF.