Overview

Clean water is also important for the Cape’s “blue economy,” where residents, visitors, and businesses rely heavily upon healthy aquatic ecosystems. Commercial and recreational fishing and shellfishing on Cape Cod, which provide millions of dollars in revenue each year, depend on the surrounding aquatic habitats to produce and sustain fish populations in abundance. In 2018, the economic value of Cape Cod’s commercial fisheries totaled over $73.6 million, accounting for over 11 percent of the economic value of the Commonwealth’s commercial fisheries (“Port by Port: Profiles and Analysis of the Massachusetts Commercial Fishery”). The economic benefits of high-quality water resources are also demonstrated by Cape’s strong tourism industry. In 2023 tourism contributed $2.7 billion to the local economy, supporting 14,100 tourism-related jobs (https://www.mass.gov/news/tourism-drives-economic-growth-in-massachusetts).

Finally, clean drinking water is critically important for human 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 through the flow of water, meaning that pollution may spread among water resources depending on many factors.

WATER POLLUTION

Most of the Cape’s coastal embayments and many freshwater ponds and lakes are suffering from some form of pollution that originates from the land (i.e., stormwater), air (i.e., atmospheric deposition), groundwater, and/or surface water (including rivers, ponds, tidal embayments, etc.). Years of intensive 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 and phosphorus) 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 algae that leads to oxygen depletion. Oxygen depletion causes fish and shellfish kills and can impact other aquatic, terrestrial, and avian wildlife through a cascading effect in the food chain. Excess phytoplankton (microscopic algae) 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. In addition, when algae die, their remains settle to the bottom and decompose, causing more oxygen depletion and releasing nutrients back into the water, feeding the cycle of excess nutrients. Finally, the buildup of decaying organic matter on the bottom of ponds, lakes and embayments often results in thick, anoxic (low oxygen) muck that is unhealthy for shellfish, fish and other aquatic organisms.

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

Ponds and lakes are also suffering from eutrophication caused by excess nutrients (Cape Cod Commission, Ponds and Lakes). While phosphorus has been targeted as the main cause of pond eutrophication, there is growing scientific evidence that nitrogen as well as phosphorus impacts the quality of freshwater ponds (Kniffin et al., 2009, Mischler et al., 2014, C. Neill, 2023).

On Cape Cod, excess nutrients originate largely from human sources and activities. The largest source of excess nitrogen and phosphorus is poorly treated wastewater (e.g., Title 5 septic systems) that discharge nutrients into groundwater. Another human activity that adds unwanted nutrients to water resources is the use of fertilizers on lawns, gardens, golf courses and farms; stormwater runoff then carries fertilizers into nearby ponds and streams. Some nitrogen also falls out from the atmosphere in precipitation; this atmospheric nitrogen largely originates from burning fossil fuels.

Harmful algal blooms and harmful cyanobacteria blooms include red tides in coastal waters and cyanobacteria blooms in freshwater ponds and lakes. In coastal waters, red tide is the common name for toxic phytoplankton that can form harmful algal blooms. Shellfish that ingest toxic phytoplankton can cause paralytic shellfish poisoning (PSP) in people who eat contaminated shellfish. The Massachusetts Division of Marine Fisheries (MA DMF) monitors coastal waters for harmful algal blooms and issues advisories and shellfish area closure notices as needed (MA DMF and red tide).

In freshwater, harmful cyanobacteria blooms thrive in nutrient-rich and warm waters. Cyanobacteria blooms are of concern because a number of common species produce toxins that can harm humans and animals if ingested (CDC, EPA). Since 2017, APCC’s Cyanobacteria Monitoring Program has documented cyanobacteria blooms in dozens of ponds throughout the Cape. APCC anticipates that this will be an increasing problem as nutrient pollution continues and the climate warms. APCC used cyanobacteria monitoring data and water quality data as two indicators of nutrient pollution for this report.

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 amounts 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. 

Mercury pollution occurs in waters throughout the Northeast. As of November 2024, the Massachusetts Department of Public Health listed 30 ponds and lakes on Cape Cod with fish consumption advisories that warn people to limit or avoid eating fish from that lake due to mercury pollution (MA DPH Fish Consumption Advisories). Mercury pollution is caused by fallout of mercury from the atmosphere, which originates from coal-burning fossil fuel plant emissions. Incineration of medical wastes and municipal wastes also contribute mercury to the atmosphere. Our assessment does not address mercury pollution, but the State of the Waters: Cape Cod website provides information on mercury pollution and state fish consumption advisories for freshwater lakes and ponds on Cape Cod.

Emerging contaminants and pharmaceutical compounds have been found in groundwater and surface water throughout Cape Cod. 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 (per- and polyfluoroacetate substances, see below). The Silent Spring Institute has been monitoring the Cape’s waters’ emerging contaminants. The Center for Coastal Studies and Silent Spring Institute also found pharmaceutical compounds in Cape Cod Bay and in groundwater near septic systems, pointing to septic systems as the source of these pharmaceutical compounds.

PFAS (per- and polyfluoroacetate 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 compounds are also known as “forever chemicals” because they are long-lasting compounds. They have been found worldwide in humans, wildlife, water, soil and the air. PFAS have been found in Cape Cod water supplies, groundwater, and ponds. As of November 2024, nine ponds on Cape Cod had advisories due to PFAS (MA DPH Fish Consumption Advisories). PFAS compounds have been linked to human health impacts such as developmental disorders, immune system disorders, thyroid hormone disruption and cancer (CDC on PFAS). APCC’s PFAS Primer provides more information on PFAS. New state regulations limiting PFAS6 in drinking water came into effect in 2021 and our drinking water grades address PFAS6.

HOW WE GRADED WATER QUALITY

To help people understand where water resources are of high or low quality on Cape Cod, APCC created this project and website to collect existing information on water quality and translate it into easily understood terms, i.e., acceptable vs. unacceptable. In the sections below, we describe which pollutants, or parameters, are used to base these evaluations. The website is a key means of collecting and distributing information to the public. Our intent is to guide public policy and investment in restoration and protection efforts. 

Using existing data, APCC grades 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 uses three grading systems, one system for coastal waters, a second system for freshwater ponds and lakes, and a third system for public water supplies that provide drinking water. Each of the grading systems scores water quality parameters. The scores are then translated into grades and based on those grades, the water resource receives a ranking category (i.e., acceptable or unacceptable for fresh- and saltwater surface waters, and excellent, good, or poor for drinking water supplies). APCC uses standardized 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;
• Allow for annual updating using the most recent available data;
• 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.

To provide the most up-to-date assessment feasible, each year the grades are updated on a moving basis by dropping the older data and adding more recent data through the previous year. However, the coastal water assessment was not updated in 2024 due to very little observed change in embayment and station grades in recent years. Any worsening conditions would not  result in modified grades in embayments already designated, as unacceptable and measurable improvements to stations seemed unlikely, given the slow implementation of mitigation strategies since 2022.

Advisory Committee: To help advise this project at its inception, APCC convened an Advisory Committee composed of experts in Cape Cod’s water pollution issues, nutrient issues, water monitoring, drinking water, aquatic ecosystems, fisheries, natural resource management and municipal management. Members of the following local, regional and state agencies, environmental nonprofit organizations and partnerships provided advice and guidance on the scoring systems described in the following sections: School for Marine and Atmospheric Sciences and Technology (SMAST), University of Massachusetts at Dartmouth; Cape Cod Commission; Center for Coastal Studies; Massachusetts Bays National Estuary Partnership; Massachusetts Office of Coastal Zone Management; Buzzards Bay Coalition; Marine Biological Laboratory, Woods Hole; Mashpee Water District; TMDL Solutions, LLC; Waquoit Bay National Estuarine Research Reserve (WBNERR); Department of Natural Resources, Town of Chatham; and Department of Health and Environment, Town of Eastham. 

• 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.

The Eutrophic Index is considered by practitioners to be a well-tested method and is also used by the Center for Coastal Studies, the Pleasant Bay Alliance, and the town of Chatham to evaluate nitrogen pollution in coastal waters monitored by these organizations.

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 are used to calculate a numerical score that indicates the degree of eutrophication. The BBC then translates scores into an assessment of water quality according to three possible grades: scores of 65 to 100 indicate Good water quality; scores between 35 and 65 indicate Fair water quality; and scores below 35 indicate Poor water quality.

Following the BBC’s method, APCC calculates numerical Eutrophic Index (EI) scores for coastal water quality from stations in coastal embayments and coastal waters around Cape Cod. However, APCC “grades” the numerical scores from individual stations in a manner that differs from the BBC. APCC assigns scores into two possible grades based on whether they indicate Acceptable water quality or Unacceptable water quality. The two grading categories were developed to indicate the type of action needed to protect or restore water quality (see below).

Grading coastal water quality at coastal stations:

EI scores greater than 65 (> 65) are graded as: “Acceptable: requires ongoing protection.”

EI scores of 65 or below (? 65) are graded as: “Unacceptable: requires 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 water quality in coastal embayments: 

APCC has taken 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 to grading embayments provides a clear indication of which embayments have portions with poor water quality that require restoration vs. embayments with good water quality that require protection.

Grading Ponds and Lakes

To grade water quality in freshwater ponds and lakes, APCC uses two methods: the Carlson Trophic Index to score water quality data, and cyanobacteria grades based on APCC’s cyanobacteria monitoring data. The two methods are described below, followed by a description of how the two grading systems are combined into one grade per pond.

Method 1: Carlson Trophic Index (CTI) scores

The first scoring method is the Carlson Trophic Index (CTI), which evaluates the trophic state of the water body in terms of three important parameters for freshwater quality: total phosphorus, 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 (in terms of algal or phytoplankton biomass) to nutrients (Carlson, 1977). Since then, it has been widely used for evaluating freshwater ponds and lakes. The Carlson Trophic Index is analogous to the Buzzards Bay Eutrophic Index in that it evaluates the degree of eutrophication in fresh water.

Similar to the Buzzards Bay Eutrophic Index for coastal water quality, the Carlson Trophic Index uses a numerical scoring system to evaluate pond trophic status. A eutrophic to hypereutrophic pond with high nutrient concentrations is characterized by high concentrations of algae, algal scums, poor water clarity due to dense algae, low to no dissolved oxygen, and CTI scores between 50 and 100. A mesotrophic pond with intermediate nutrient concentrations is characterized by moderately clear water, intermediate amounts of aquatic plants and algae, low dissolved oxygen during the summer, and CTI scores between 40 and 50. At the low end of the nutrient spectrum, an oligotrophic pond with low nutrient concentrations is characterized by clear well-oxygenated water, healthy aquatic plants, little to no algal growth, and CTI scores between 0 and 40.

APCC translates CTI scores into two possible grades for pond water quality:

CTI scores of less than 50 (< 50) are graded as “Acceptable: requires ongoing protection.”

CTI scores of 50 or above (? 50) are graded as “Unacceptable: requires immediate restoration.”

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

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

Data quality needed for CTI scoring: Many datasets for pond water quality for Cape Cod ponds are older, i.e., at least five years old or more. Using older data to grade ponds would cause grades to reflect conditions that existed at the time when water samples were collected. Conditions in ponds may have changed since such older data were collected. In order to provide an evaluation of recent pond conditions, this project screens out older data on a moving basis each year. For this report, APCC screened out pond data older than 2019 and required at least three years of data from 2019 through 2023, as well as data for all three CTI parameters (chlorophyll, total phosphorus, and Secchi disk depth). These stringent data quality requirements resulted in only 68 ponds with sufficient water quality data to enable grading this year using the Carlson Trophic Index. As the Cape has 890 ponds, this points out the severe shortage of recent Cape-wide pond monitoring data to inform pond management and protection measures.

Method 2: Cyanobacteria Grades Using Cyanobacteria Monitoring Data

Since 2018, APCC has been monitoring cyanobacteria and cyanobacteria blooms in over 100 freshwater ponds on Cape Cod. Cyanobacteria blooms occur when there are sufficient nutrients to stimulate growth of these photosynthetic bacteria. Warmth and sunlight are other factors that stimulate cyanobacteria growth. In the absence of nutrients or when nutrient concentrations are very low, cyanobacteria growth is generally minimal. (Sylvain Merel et. Al, 2013) Cyanobacteria blooms therefore represent an indicator of nutrient enrichment in freshwater ponds.

In 2024, APCC’s Cyanobacteria Monitoring Program finalized the Cape Cod Cyanobacteria Monitoring Program Quality Assurance Project Plan (CCCMP QAPP), which was approved by the EPA and MassDEP in July 2024. Prior to 2024, the Cyanobacteria Monitoring Program used an EPA-approved?protocol?developed by EPA for the Cyanobacteria Monitoring Collaborative and refinements added under the guidance of Dr. James Haney (emeritus professor, University of New Hampshire) and Nancy Leland of Lim-tex, Inc. (Leland and Haney, 2018; Leland, Haney, Conte, Malkus-Benjamin and Horseley, 2019). APCC’s CCCMP QAPP follows the methods described in the EPA-approved protocol, ensuring consistent sampling and analysis methods over time. Data collected from ponds includes photographs and field observations, microscopy to identify composition and dominance of cyanobacteria genera,?and concentrations of phycocyanin and chlorophyll pigments indicative of the biomass of cyanobacteria vs. biomass of other algae and phytoplankton, respectively. By monitoring biweekly from May to October, APCC?tracks changes in?cyanobacterial?composition, dominance, and abundance throughout the season. The monitoring data are translated into three risk levels, which are reported to public health officials and the public to raise awareness of potential risks and to?assist public health officials by providing credible monitoring data to inform proactive management actions to protect public safety. To learn more, visit APCC’s Cyanobacteria Monitoring Program.

The scarcity of recent pond water quality data needed to calculate CTI scores led APCC in 2020 to adopt a second method of grading ponds using cyanobacteria monitoring data to provide an additional measure of pond health. The use of cyanobacteria data helps to fill the gap in water quality data by providing a different measure of trophic status that relates directly to cyanobacteria biomass. APCC’s cyanobacteria grading system utilizes our three-tiered risk warning system for assigning monitored cyanobacteria concentrations into “Low,” “Moderate” and “High” risk tiers, which describe potential risks in terms of exposure to children, pets, exposure during recreational activities, toxin concentrations, and presence of visible cyanobacteria blooms. To grade ponds using cyanobacteria risk tiers, the tiers are assigned into “Acceptable” or “Unacceptable” grades according to the risk definitions. The previous year’s monitoring results are used (i.e., for this report, cyanobacteria data collected in 2023 were used). The highest risk tier documented in a pond during the monitoring season is used to assign a grade.

Cyanobacteria risk tiers and grading system:

APCC used the same cyanobacteria risk tiers as in the last two years of the State of the Waters: Cape Cod report (2022-2023). These risk tiers were adopted in 2022 for APCC’s Cyanobacteria Monitoring Program. The risk tiers reflect input from local and state public health officials and scientists, incorporation of state limits for cyanobacteria toxin in recreational waters, and a new regional capability for cyanobacteria toxin testing at the Barnstable County water quality lab. The risk tiers are given below. Note: The current APCC website has our most up to date risk tiers.

Acceptable (“Low” risk): No concerning cyanobacteria results at the time and place of sampling. To the best of APCC’s knowledge and based on our monitoring results, regular recreational usage of the pond is safe with respect to cyanobacteria and toxins. Map color is blue.

Potential for Concern (“Moderate” risk): Monitoring results or the presence of cyanobacteria scum at the time and place of sampling indicate a potential for increased risk for exposure to cyanobacteria toxins approaching, but below, state standards. Conditions do not yet warrant the posting of a recreational human health advisory according to guidelines from the Massachusetts Department of Public Health (MDPH).?While these conditions pose low health risks to adults, risks are higher for children or pets based on lower body mass, particularly if contaminated water is incidentally ingested. Children may inadvertently consume pond water while swimming and pet exposure can result from drinking or ingesting pond water or from grooming after swimming. Map color is yellow. Map color yellow with crosshatching indicates a municipal pet advisory has been issued.

Use Restriction Warranted (“High” risk): Monitoring results at the time and place of sampling indicate the pond is unsafe for recreation by humans and pets based on one or more of the following criteria: 1) presence of microcystin at or above state standards (8 parts per billion or ppb microcystin) as described in MDPH guidance; 2) presence of significant cyanobacteria scum layers according to MDPH guidance; 3) a municipal health agent issues a closure for any other reason related to cyanobacteria.?Recreational risk to adults is moderate following exposure. Recreational risks are especially high for children and pets following exposure through accidental ingestion of contaminated water. Children may inadvertently consume pond water while swimming and pet exposure can result from ingestion or directly drinking pond water or from grooming after swimming. Due to lower body masses, children and pets are more susceptible to cyanobacteria risks than adults. Map color is red. Map color red with crosshatching indicates a municipal advisory has been issued.

The cyanobacteria grading system for cyanobacteria data is given below:

If all cyanobacteria levels for the entire sampling season were in the “Low” and/or “Moderate” risk tiers, the pond was graded as “Acceptable: ongoing protection is needed”; and

If one or more of the cyanobacteria levels were in the “High” risk tier, the pond was graded as “Unacceptable: requires immediate restoration.”

Combined Pond Grading System

As in previous years, APCC’s combined pond grading system utilizes available Carlson Trophic Index grades and cyanobacteria grades, as follows:

1. Carlson Trophic Index scores and grades for ponds were calculated for ponds where water quality data from 2018 on was available, and where at least three years of data were available for all three CTI parameters (chlorophyll, total phosphorus, and Secchi disk depth).

2. Cyanobacteria monitoring data from 2023 were used to grade ponds using APCC’s revised cyanobacteria risk tiers and grading system described above:

a. Ponds with cyanobacteria levels in the “High” risk tier were graded as “Unacceptable: requires immediate restoration.”

b. Ponds with cyanobacteria levels in the “Low” and “Moderate” risk tiers were graded as “Acceptable: requires ongoing protection.”

3. If a pond had both Carlson Trophic Index grades and Cyanobacteria grades:

a. The pond was graded as “Acceptable: requires ongoing protection” only if both grades were Acceptable.

b. The pond was graded as “Unacceptable: requires immediate restoration” if at least one of the grades was Unacceptable.

4. If a pond had only one grade (i.e., Carlson Trophic Index grade or Cyanobacteria grade), that grade was used as the sole determinant of the overall pond grade.

Grading Public Water Supplies of Drinking Water

The grading system for public drinking water supplies (PWSs) is based on a modification of 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 evaluates 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 and consumers, not the quality of the water as it comes out of the tap, which can be affected by pipes and plumbing in the distribution system and in homes and businesses. APCC evaluates 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.

To grade Cape Cod public water supplies, APCC uses publicly available Consumer Confidence Reports (CCRs) for the previous year to determine if water quality met existing state and federal drinking water standards (i.e., Maximum Contaminant Levels, or MCLs). This year, 2023 CCRs were reviewed for grading.

The grading system used this year is the same as that used last year, i.e., a three-level grading system: “Excellent,” “Good,” and “Poor.” These are described below:

Excellent: In 2023, finish water met all existing state and federal health and reporting standards.

Good: In 2023, finish water had one or more exceedances of the Total Coliform MCL and/or no more than one violation of an existing state or federal standard that posed a risk to public health, and that violation was neither chronic nor repeated.

Poor: In 2023, finish water had violations of two or more existing state and/or federal standards that posed a risk to public health or a violation that was repeated or persisted through more than one sampling round. 

In addition, APCC identified PWSs that had detectable PFAS6 but met the state standard with an asterisk (*). In April 2021, the new Massachusetts drinking water standard for PFAS6 went into effect (MassDEP PFAS Drinking Water Regulation Quick Reference Guide). PFAS refers to per- and polyfluoroalkyl substances, a family of manmade chemicals used in industry and consumer products worldwide since the 1950s to manufacture stain-resistant, water-resistant, and non-stick products. Thousands of PFAS compounds are known. PFAS6 refers to the sum of six per- and polyfluoroalkyl substances. The state’s PFAS6 standard is 20 parts per trillion (ppt) based on the average of the monthly samples over a quarter. If any one sampling location is in violation, then the PWS is in violation. If any sample result would cause the quarterly average to exceed the PFAS6 MCL, the PWS is immediately in violation and begins compliance actions.

Regional data sources. These sources provided data covering multiple embayments or large areas of the Cape:

• Association to Preserve Cape Cod: 2023 cyanobacteria monitoring data for freshwater ponds located in the towns of Barnstable, Bourne, Brewster, Chatham, Dennis, Eastham, Falmouth, Harwich, Mashpee, Orleans, Provincetown, Sandwich, Truro, Wellfleet, and Yarmouth;
• Partners who assisted APCC with cyanobacteria monitoring included Brewster Ponds Coalition, Falmouth Water Stewards, Friends of Chatham Waterways, Friends of Long Pond Marstons Mills, Orleans Ponds Coalition, Oyster Pond Environmental Trust, the towns listed above, and other organizations and individuals;
• Barnstable Clean Water Coalition: coastal water quality data for stations located in the Three Bays embayment and pond water quality data;
• Buzzards Bay Coalition: Eutrophic Index scores for coastal stations and embayments located along the coasts of Falmouth and Bourne in Buzzards Bay;
• Center for Coastal Studies: pond water quality data and coastal water quality data for stations located in embayments on Cape Cod Bay, Nantucket Sound and Vineyard Sound;
• Cape Cod Commission: coastal and pond water quality data collected by and for the Cape Cod Regional Water Quality Database, a project to collect and make publicly available all water quality monitoring data for the Cape. The project was funded by the EPA Southeast New England Coastal Watershed Restoration Program (EPA SNEP);
• Cape Cod Commission and University of Massachusetts at Dartmouth, School of Marine and Atmospheric Science and Technology (SMAST): Pond and Lake Stewards (PALS) data for pond water quality (note: most of the pond data provided by towns and organizations listed below was collected by PALS and SMAST);
• Pleasant Bay Alliance: Eutrophic Index scores for stations located in Pleasant Bay; and
• Waquoit Bay National Estuarine Research Reserve (WBNERR): coastal water quality data for stations located in Waquoit Bay.

Municipal data sources:

• Town of Barnstable: coastal and pond water quality data;
• Town of Brewster: pond water quality data for one pond;
• Town of Chatham and Pleasant Bay Alliance: coastal Eutrophic Index scores for coastal stations located in Chatham and Pleasant Bay;
• Town of Dennis: coastal water quality data;
• Town of Eastham: coastal and pond water quality data;
• Town of Harwich: coastal and pond water quality data;
• Town of Mashpee: coastal and pond water quality data; and
• Town of Orleans: coastal and pond water quality data.

Data quality

In order to evaluate recent water quality conditions, APCC applies data quality standards that include using the most recent and complete data available. Data quality requirements for grading water quality data are summarized below.

Coastal water quality data: Coastal water quality data was not assessed in 2024; this report includes the grading from the 2023 report. For the 2023 report, APCC collected the most recent available coastal water quality data up to and through 2022 from the data sources listed above. Our criteria for grading coastal water quality data included at least five years of data from 2018 on (e.g., 2018, 2019, 2020, 2021 and 2022). There was one exception: Harwich coastal water quality data where data from 2017, 2018, 2019, 2021, and 2022 were used for grading (i.e., monitoring in 2020 was suspended due to the COVID-19 pandemic).

Freshwater pond and lake water quality data: Since 2000, the Cape Cod Ponds and Lakes 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 this 2024 report, APCC collected pond water quality data from the sources listed above. Our data quality requirements for grading pond water quality data included at least three years of data from 2019 on, and data for all three Carlson Trophic Index parameters (chlorophyll, transparency, and total phosphorus).

Cyanobacteria data for ponds and lakes: For this 2024 report, APCC used 2023 cyanobacteria monitoring data collected by APCC’s Cyanobacteria Monitoring Program. Cyanobacteria monitoring data were collected according to an EPA-approved Quality Assurance Project Plan for cyanobacteria monitoring.

Drinking water and public water supplies: For this 2024 report, APCC collected each town’s public-right-to-know reports for 2023 drinking water quality, also known as the Consumer Confidence Reports (CCRs) for drinking water. CCRs are posted on each town’s website. Links to the CCRs are provided under Resources, in the pop-ups on the interactive viewer, and in our Public Water Supplies grading sheet. APCC used the CCRs to grade water quality and compliance with existing drinking water regulations.

RESULTS

Coastal waters were not scored in 2024 due to very little observed change in embayment and station grades in recent years. The 2023 grades for coastal embayments and stations along with the 2024 grades for freshwater ponds and public water supplies are provided as maps in this report. The analyzed data are provided by searching Resources on the State of the Waters: Cape Cod website (https://capecodwaters.org). The data resource links provide access to data from individual coastal stations and embayments as well as a summary file entitled “2024 Summary of SOTW Grades.”

Coastal embayments and coastal stations

Coastal embayments:

• The number and percentage of Unacceptable embayments in 2023 remained the same as in 2022: i.e., 43 embayments or 90% of graded embayments were Unacceptable.
  • In the 2022 report, there were 43 embayments or 90% of graded embayments graded as Unacceptable.
  • In our 2021 report, 41 embayments or 87% were Unacceptable.
  • In our 2020 report, 38 embayments or 79% were Unacceptable.
  • In our 2019 report, 32 embayments or 68% were Unacceptable.
  • Over the past five years of reporting, the number and percentage of Unacceptable embayments steadily increased to a high of 43 embayments and 90% in the 2022 report and then remained level this year.
• The number and percentage of Acceptable embayments in 2023 remained the same as in 2022: i.e., only five embayments or 10% of graded embayments were Acceptable.
  • In our 2022 report, there were five embayments or 10% of graded embayments that were acceptable.
  • In our 2021 report, six embayments or 13% of graded embayments were Acceptable.
  • In our 2020 report, 10 of 48 embayments or 21% were Acceptable.
  • In our 2019 report, 15 of 47 embayments or 32% were Acceptable.
  • Over the past five years of reporting, the number of Acceptable embayments steadily decreased to a low of 10% in the 2022 report and then remained level in 2023.
• There were 48 embayments graded in 2023, the same as the 48 embayments graded in 2022. In 2021, 47 embayments were graded. In 2020, 48 embayments were graded, and in 2019, 47 embayments were graded.
• As in 2022, all embayments on Nantucket Sound were Unacceptable, all embayments in Buzzards Bay were Unacceptable except for Quissett Harbor, which was Acceptable, and Pleasant Bay and Nauset Estuary were Unacceptable.
• Cape Cod Bay continued to have the largest number of Acceptable embayments (four) in 2023.
• There were no embayments that improved from Unacceptable to Acceptable in 2023.

Coastal stations:

• In 2023, there were more coastal stations (226) with sufficient data to grade water quality, with 166 (73%) stations graded as Unacceptable.
  • In our 2022 report, there were 191 coastal stations, of which 131 were Unacceptable, representing 69% of graded stations, and 60 were Acceptable, representing 31% of graded stations.
  • In our 2021 report, there were 197 coastal stations, of which 133 were Unacceptable, representing 68% of graded stations.
  • In our 2020 report, there were 152 coastal stations, of which 106 were Unacceptable, representing 70% of graded stations.
  • In our 2019 report, there were 152 coastal stations, of which 98 were Unacceptable, representing 64% of graded stations.
  • The higher number and percentage of Unacceptable stations in 2023 is due in part to a large number of stations added in Mashpee and a smaller number added in Dennis. Most of these were Unacceptable. These results emphasize the fact that the Cape’s coastal waters continue to suffer from nutrient pollution.
• In 2023, there were 60 Acceptable stations, the same number as last year. Due to the increase in total number of stations, the percentage of Acceptable stations decreased to 27% (down from 31% in our 2022 report).
  • In our 2022 report, there were 60 Acceptable stations, or 31% of graded stations.
  • In our 2021 report, there were 64 Acceptable stations, or 32% of graded stations.
  • In our 2020 report, there were 46 Acceptable stations, or 30% of graded stations.
  • In our 2019 report, there were 54 Acceptable stations, or 36% of graded stations.
  • The decrease in percentage of Acceptable stations reflects the widespread nature of eutrophic conditions throughout our coastal waters.
• There were more (226) coastal stations graded in 2023, an increase of 35 stations from our 2022 report when there were 191 coastal stations graded. Since 2019, the number of coastal stations with sufficient data to grade has generally increased.
• The increase in number of stations in 2023 (35 stations) was due largely to 30 new stations located in Mashpee coastal waters. All but one of these coastal stations were Unacceptable. The results support and strengthen our assessment of Popponessett Bay and Shoestring Bay as being Unacceptable due to eutrophication.

Freshwater Ponds

• This year, 138 ponds had sufficient water quality data and/or cyanobacteria data to enable grading.
  • In our 2023 report, there were 139 ponds graded.
  • In our 2022 report, there were 151 ponds graded.
  • In our 2021 report, there were 109 ponds graded.
  • In our 2020 report, there were 93 ponds graded.
  • In 2019, there were 149 ponds graded.
  • The 138 graded ponds this year represent only 16% of the Cape’s 890 freshwater ponds, indicating that there is an ongoing shortage of recent data for grading most of the Cape’s ponds.
• This year, over one-quarter of all graded ponds were Unacceptable, i.e., there were 39 Unacceptable ponds, or 28% of all graded ponds.
  • In our 2023 report last year, there were 52 Unacceptable ponds, representing 37% of all graded ponds.
  • In our 2022 report, there were 59 Unacceptable ponds, representing 39% of all graded ponds.
  • In our 2021 report, there were 38 Unacceptable ponds, representing 35% of graded ponds.
  • In our 2020 report, there were 39 Unacceptable ponds, or 42% of all graded ponds,
  • In 2019, there were 58 Unacceptable ponds, or 39% of all graded ponds.
• Over two-thirds of graded ponds were Acceptable, i.e., there were 99 Acceptable ponds, representing 72% of graded ponds.
  • In our 2023 report last year, there were 87 Acceptable ponds, representing 63% of graded ponds.
  • In our 2022 report, there were 92 Acceptable ponds, representing 61% of graded ponds.
  • In our 2021 report, there were 71 Acceptable ponds, or 65% of Acceptable ponds.
  • In our 2020 report, there were 54 Acceptable ponds, or 58% of graded ponds.
  • In our 2019 report, there were 91 Acceptable ponds, or 61% of graded ponds.
• This year, 68 ponds had sufficient water quality data to grade using the Carlson Trophic Index, compared to 64 ponds last year and 36 ponds in 2021. Of the 68 ponds, 36, or 53%, were Acceptable and 32, or 47%, were Unacceptable. Over time, the percentage of Unacceptable CTI grades has increased from 33% in 2021, to 46% in 2022, to 50% in 2023, but decreased slightly this year to 47% in 2024.
• A total of 118 ponds were graded using APCC’s 2023 cyanobacteria monitoring data. Of these, 105 ponds, or 89%, were Acceptable and 13 ponds, or 11%, were Unacceptable. The use of cyanobacteria data enabled an additional 70 ponds to be graded. Over time, the percentage of Unacceptable cyanobacteria grades has decreased from 40% in 2021, to 28% in 2022, to 20% in 2023, to 11% in 2024.
• Only 47 ponds had both Carlson Trophic Index and Cyanobacteria grades. Of these ponds with dual grades, 25 ponds had Acceptable grades, and 16 ponds had Unacceptable grades.
• The percentages of Acceptable vs. Unacceptable grades for ponds graded using either the Carlson Trophic Index or cyanobacteria were as follows: 53% of ponds with CTI grades were Acceptable compared to 89% of ponds with cyanobacteria grades of Acceptable. Likewise, 47% of ponds with CTI grades were Unacceptable compared to 11% of ponds with cyanobacteria grades of Unacceptable. More data are needed to determine whether the differences are significant.
• Towns with sufficient pond water quality data to enable grading using the Carlson Trophic Index included Barnstable (32 ponds), Eastham (9 ponds), Falmouth (1 pond), Harwich (7 ponds), Mashpee (4 ponds), and Orleans (14 ponds).
• Towns with 2023 cyanobacteria monitoring data for ponds included Barnstable (32 ponds), Eastham (9 ponds), Falmouth (1 ponds), Harwich (6 ponds), Mashpee (5 ponds), and Orleans (12 ponds).

Public Water Supplies 

Grades for public water supplies are summarized below.

• A total of 21 public water supplies were graded for the quality of their finish water.
• Nineteen (19) public water supplies on the Cape had “Excellent” water quality, meaning that they met all state and federal drinking water standards: Barnstable COMM, Barnstable Fire District, Cotuit Water Department, Hyannis Water System, , North Sagamore Water District, Town of Brewster Water Department, Town of Chatham Department of Public Works Water Division, Town of Dennis Water District, Town of Eastham Water Department, Town of Falmouth Water Department, Town of Harwich Water Department, Mashpee Water District, Town of Orleans Water Department, Town of Provincetown Water Department, Town of Wellfleet Municipal Water System, Town of Yarmouth Water District, Otis Air National Guard, Town of Sandwich Water District and the Upper Cape Regional Water Supply Collaborative.
• However, of the 19 public water suppliers with “Excellent” grades, 10 had detected PFAS6 in some groundwater wells, but concentrations did not exceed the new state standard for PFAS6 that became effective in 2021 (i.e., they met the state standard). The ten PWSs were Barnstable COMM, Barnstable Fire District, Cotuit Water Department, Hyannis Water System, Town of Falmouth Water Department, North Sagamore Water District, Otis Air National Guard, Town of Dennis Water District, Mashpee Water District, and Town of Yarmouth Water District.
• Nine of the 21 public water supplies had “Excellent” water quality with no detections of PFAS6. These were Town of Brewster Water Department, Town of Chatham Department of Public Works Water Division, Town of Eastham Water Department, Town of Harwich Water Department, Town of Orleans Water Department, Town of Provincetown Water Department, Town of Sandwich Water District, Town of Wellfleet Municipal Water System, and the Upper Cape Regional Water Supply Collaborative.
• Two public water suppliers were graded as having “Good” water quality, based on their detection of total coliform bacteria in finish water: Buzzards Bay Water District and Bourne Water District. The presence of total coliform bacteria is used as an indicator that harmful enteric bacteria (e.g., E. coli) may be present. Both PWSs followed up with appropriate response measures and did not detect E. coli. PFAS6 were detected in Bourne Water District, but concentrations did not exceed the new state standard for PFAS6 that became effective in 2021 (i.e., they met the state standard).
• There were no PWSs graded as “Poor” in 2024.

For more information on PFAS, see APCC’s PFAS Primer.

Discussion

This is the sixth annual report on the State of the Waters: Cape Cod, which provides an assessment of water quality in freshwater ponds and public water supplies using the most recent available data and of water quality in coastal embayments using the assessment from 2023. Collectively, these annual reports show that the Cape’s coastal waters and freshwater ponds continue to suffer from eutrophication due to excess nutrients, primarily from septic systems located in the watersheds of coastal embayments. In contrast, public water supplies were largely “Excellent” with only two graded as “Good” and none graded as “Poor,” indicating that overall, drinking water supplies on Cape Cod were excellent.

This report also covers the third year (2023) since new state regulations limiting PFAS6 concentrations in drinking water came into effect in 2021. While PFAS6 was detected in 11 of the 21 public water supply systems that serve Cape Cod, all 11 met the new DEP drinking water regulations for PFAS6. Nevertheless, the widespread occurrence of PFAS6 in raw water in public water supplies calls for ongoing monitoring, planning, financing, and implementation of effective treatment methods.

Coastal embayments and stations

Coastal embayments were not assessed in 2024; the results discussed here refer to the assessment done in 2023. The majority of Cape Cod’s coastal embayments (90%) continued to be Unacceptable, the same as in our 2022 report. Over the past five years of State of the Waters reporting, the number of Unacceptable embayments steadily increased to 90% in our 2022 report and then remained level this year. Conversely, the number of Acceptable embayments steadily decreased over the past five years, reaching a low of 10% of embayments in our 2022 report and then remaining level this year. A larger percentage (73%) of the 226 coastal stations had Unacceptable water quality and less than one-third (27%) had Acceptable water quality, a lower percentage than in previous years. These results show that coastal eutrophication continues to impact the majority of the Cape’s embayments.

Most of the Cape continues to be served by septic systems with only small areas served by municipal sewers . Septic systems located in the watersheds of coastal embayments are the main source of excess nutrients in embayments. A number of towns have made significant steps toward managing nutrients by approving construction of modern wastewater treatment projects. While embayment water quality has yet to improve as a result, as these projects are implemented over the next few years, the region should begin to see lower nutrient loadings that should be reflected in improving water quality in selected embayments.

Ponds

Pond grades improved slightly in comparison to 2023 grades, with 28% of the 138 graded ponds being categorized as Unacceptable and 72% of the graded ponds being categorized as Acceptable. While the CTI grade percentages are similar to last year’s percentages, the grade percentages based on the cyanobacteria monitoring data have improved since last year. This difference in trends between the two assessment methods is not entirely unexpected, since each method measures eutrophication in a different way. This is explained in more detail below. The similar CTI grade percentages this year compared to years past indicate that pond water quality has generally remained static. This year’s report also confirms an ongoing serious shortage of recent pond data from the past five years, as 138 ponds represent only 16% of the Cape’s 890 freshwater ponds and lakes.

As APCC’s understanding of pond water quality has expanded, much has been learned about the scope of pond impairment. While lacking a sufficiently robust and lengthy data record upon which to base trend analyses, it appears that based on recent data, approximately one-third of graded ponds achieve Unacceptable status in any given year, and that there is considerable variability from year to year in which ponds trigger that designation. While the conditions representing impairment exist in many ponds – perhaps a majority of ponds Cape-wide – the actual confluence of events that drive poor water quality conditions in any given pond in a particular year remain hard to predict, given the lack of detailed and multi-year data.

A comprehensive review and assessment of overall pond health on Cape Cod is hampered by data quality issues as well as insufficient data. To grade pond water quality, APCC uses two methods, the first being the Carlson Trophic Index, an index of water quality that describes the trophic status of a water body based on total phosphorus, chlorophyll and water clarity; i.e., it is a measure of phytoplankton productivity due to nutrient loading where phytoplankton include algae and cyanobacteria. Many pond water quality data sets are older, e.g., five years old or more. Using older data to grade ponds would cause grades to reflect conditions that existed at the time when water samples were collected and analyzed. Conditions in ponds may have changed since these older data were collected. For this report, APCC screened out pond water quality data older than 2019 and ponds with less than three years of data collected. Using these more stringent data quality requirements for grading resulted in only 68 ponds having sufficient water quality data to enable grading using the Carlson Trophic Index. This points out the severe shortage of more recent Cape-wide pond monitoring data to inform pond management and protection measures.

To help fill the gap in freshwater pond data, APCC utilized the results of our Cyanobacteria Monitoring Program. Since 2018, APCC has been monitoring cyanobacteria blooms in over 100 freshwater ponds on Cape Cod. Cyanobacteria blooms occur when there are sufficient nutrients, warmth, and sunlight to stimulate growth of these photosynthetic bacteria. Cyanobacteria blooms represent another way to assess phytoplankton productivity in ponds and complement the use of the Carlson Trophic Index. A total of 118 ponds were monitored for cyanobacteria in 2023, many of which also had enough water quality data to enable grading using the Carlson Trophic Index. The use of cyanobacteria data enabled an additional 70 ponds to be graded.

In 2024, of the 68 ponds with sufficient water quality data to be graded using the Carlson Trophic Index, 47% were Unacceptable. Of the 118 ponds graded using cyanobacteria tiers, 11% were Unacceptable. The differences in percentages of Unacceptable grades between the two grading systems reflects the fact that they measure eutrophication in two different ways: The Carlson Trophic Index measures phytoplankton productivity based on chlorophyll, total phosphorus, and Secchi disk depth (i.e., all algae) while the cyanobacteria grade measures cyanobacteria productivity based on phycocyanin rather than chlorophyll. The Carlson Trophic Index is a measure of non-cyanobacteria algal productivity representing data from the past three to five years, while the cyanobacteria grade measures cyanobacteria productivity from just one year at time. The CTI is a widely accepted measure of water quality, whereas cyanobacteria blooms represent the biological response to water quality and, importantly, weather. Together the two grading systems measure all algal productivity.

Finally, over time there have been changes in percentages of Unacceptable grades for both Carlson Trophic Index and cyanobacteria grades. Over time, the percentage of Unacceptable CTI grades has increased from 33% in 2021, to 46% in 2022, to 50% in 2023, and has now seen a slight decrease to 47% in 2024. Over the same time period, the percentage of Unacceptable cyanobacteria grades has decreased from 40% in 2021, to 28% in 2022, to 20% in 2023, to 11% in 2024. These changes occurring hand-in-hand suggest that general algal productivity in ponds has been increasing relative to cyanobacteria productivity. More data are needed to explore this possibility. In either case, algal productivity and cyanobacteria productivity are related to nutrients, light, and temperature.

Public Water Supplies

The majority of public water supplies (19 of 21) met all existing state and federal drinking water quality standards and were graded as “Excellent.” The two exceptions graded as “Good” due to total coliform indicate that the potential for bacterial contamination always exists and monitoring is always needed. There were no “Poor” grades for 2023 drinking water data.

This report covers the third year since new state regulations limiting PFAS6 concentrations in drinking water to 20 parts per trillion (ppt) became effective in 2021. While PFAS6 was detected in 11 of the 21 public water supply systems, all 11 of these systems met the state’s PFAS6 standard. The widespread detection of PFAS6 in public water supplies calls for ongoing monitoring as well as planning and implementation of effective treatment methods. Towns either have provided treatment to remove PFAS6 or are planning to provide treatment.

Other water quality issues of concern

• Private wells were not addressed in this project. APCC strongly recommends that private well owners have their water tested and, if needed, treated.
• 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:
  • 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; and
• A number of freshwater cyanobacteria species produce toxins that are harmful to humans and animals if ingested. Public surface water supplies can become contaminated by cyanobacteria and cyanotoxins, and public water suppliers who utilize surface water are required by state and federal laws to guard against cyanotoxins in drinking water. This issue is of limited scope on Cape Cod, as only Falmouth utilizes a surface water source for a portion of its public drinking water.
• Harmful bacteria in coastal waters and freshwater ponds, lakes and streams 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. Bacteria in beach water quality and shellfish area water quality are monitored by Barnstable County and the state Division of Marine Fisheries.
• Mercury contamination of surface water continues to be of concern. As of November 2024, there were 30 ponds on Cape Cod with fish consumption advisories due to mercury and nine with advisories due to PFAS (MA Fish Consumption Advisories). Ten of the 15 towns on Cape Cod had fish consumption advisories as of November 2024: Barnstable, Bourne, Brewster, Dennis, Falmouth, Harwich, Mashpee, Sandwich, Truro, and Wellfleet. Mercury originates from atmospheric fallout of mercury emissions from coal-burning power plants.
  • In 2023, there were 26 ponds and lakes on the Cape with fish consumption advisories due to high levels of mercury and in some cases PFAS.
  • In 2022, there were 32 ponds and lakes on the Cape with fish consumption advisories due to high levels of mercury and in some cases PFAS.
  • In 2021, there were 29 ponds with fish consumption advisories.
  • In 2020, there were 24 ponds with fish consumption advisories.
• Nine ponds had fish consumption advisories due to PFAS. Towns with such ponds included Yarmouth, Sandwich, Bourne, Falmouth, and Mashpee (MA Fish Consumption Advisories).
• Predicted climate change impacts 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 changes will impact water quality and exacerbate the harmful effects of existing pollutants. Climate change may also impact public water supplies through protracted drought.
• Continued development of land in critical natural resource areas and drinking water protection areas is a threat to water quality. With only 14% of Cape Cod land left undeveloped and unprotected, and with most of that remaining unprotected land located within critical natural resource areas, it is vital that towns prioritize efforts to acquire and protect land within these sensitive resource areas. See APCC’s “Hanging in the Balance” report for more information.
• Degrading polystyrene foam, traditionally used as flotation for docks and swim floats, has been observed washing up on the shorelines of freshwater ponds and coastal waterways, contributing to microplastics in these ecosystems. Several local pond groups and other local organizations are raising awareness of this problem, and some towns have enacted regulations banning exposed polystyrene foam and requiring encapsulated floats.

Filling the gaps: recommendations for monitoring

Monitoring is crucially important to understand current conditions and for tracking progress in improving and protecting water quality. Based on our findings, APCC provides the following recommendations for monitoring:

• Coastal embayments need ongoing monitoring to collect up-to-date information on water quality in order to assess whether wastewater management measures and protection measures are working and to determine when success has been achieved.
• Monitoring of four more coastal embayments is needed: Red River in Chatham and Harwich, Hatches Harbor in Provincetown, Great Sippewissett Marsh in Falmouth, and Salt Pond in Falmouth. These embayments are listed in the 208 Water Quality Plan as nutrient-impacted coastal embayments.
• In our 2022 report, APCC recommended expanding pond monitoring to obtain water quality data from a larger number of ponds. In 2022, the Cape Cod Commission received funding for a 208-scale study of ponds across the region called the Cape Cod Freshwater Initiative. The initiative enables the Cape Cod Commission and its partners to undertake a comprehensive assessment of the quality of the Cape’s freshwater resources in order to establish a regional plan for restoring and protecting the Cape’s ponds and lakes. In late 2022, APCC was contracted by the Commission to conduct the “Cape Cod Pond Monitoring Program” to monitor 50 ponds seven times per year for three years to collect water quality data. Monitoring got underway in early 2023 and the first year of monitoring was completed in November 2023. In 2024, monitoring started back up in March and was completed in November 2024. Pond monitoring should be expanded to many more ponds and lakes throughout the Cape, particularly those where there are swimming beaches, public access, and/or sensitive resources (e.g., diadromous fish, rare species, wildlife).
• Cyanobacteria monitoring of ponds should be expanded to more ponds, as it provides a useful measure of eutrophication based on cyanobacteria and complements conventional water quality monitoring.
• The PALS program is useful as a “screening tool” to identify ponds where more in-depth monitoring and assessment is needed to determine causes, extent and severity of problems. However, pond monitoring should be conducted more frequently than the once-a-year snapshot that is typically provided by the PALS program. The “Cape Cod Pond Monitoring Program” is an example of a more comprehensive pond monitoring program, and more towns and organizations should support and participate in this program.
• Newer, more recent pond data should be utilized to assess pond conditions and inform restoration and protection efforts.
• Monitoring of pond water quality and cyanobacteria blooms should be conducted hand-in-hand so that water quality data can be used to help predict where serious cyanobacteria blooms may occur, and vice versa.
• Public water suppliers should expand their monitoring of PFAS, emerging contaminants and cyanobacteria to help safeguard public health.

SUCCESS STORIES

Despite the challenges and the need for much greater action in every town, there have been some successes in addressing nutrient pollution. These successes include the following:

• Passage of state legislation in 2018 that established the Cape Cod and Islands Water Protection Fund to provide a non-property tax-based source of funds to help Cape Cod and the Islands pay for necessary wastewater infrastructure and water quality remediation efforts. Through 2024, this fund has provided $240 million to nine towns to assist them with wastewater management and to provide dollar-for-dollar property tax relief to residents of Barnstable County.
• Barnstable County’s alternative septic system testing center has been testing the efficacy of different alternative septic systems and has identified several as being potentially useful.
• Wastewater management projects in Chatham, Falmouth, Mashpee, Barnstable, Yarmouth, Dennis, Harwich, Orleans, and Provincetown.
• Alternative wastewater treatment methods are being tested or utilized in towns across Cape Cod.
• Partnering agreements between towns to share public wastewater treatment facilities (e.g., Harwich and Chatham), including first-ever sewers installed in Harwich.
• In response to revisions to Title 5 state’s septic code, almost every town on Cape Cod is seeking a Watershed Permit.
• Intermunicipal agreement between Mashpee, Sandwich and Barnstable for nitrogen load sharing for the cleanup of Popponesset Bay.
• Intermunicipal agreement between Mashpee, Falmouth, and Sandwich for nitrogen load sharing mitigation for Waquoit Bay.
• Pond restoration success stories have been compiled by the Cape Cod Commission. Success stories for freshwater ponds are fewer because ponds have not received the attention that coastal embayments have received.
• Cape Cod Commission also has an estuarine watershed report for each major watershed on the Cape.
• Barnstable County Cape Cod AquiFund offers low-interest betterment loans to Cape Cod homeowners faced with the cost of repairing or replacing failed septic systems, upgrading to alternative septic system technologies, as well as connecting to municipal sewers.
• The town of Orleans passed a resolution to be a pollinator-friendly community that avoids pesticide use and promotes more native species. Its special town meeting in 2023 passed a home rule petition to ban pesticide use in the town. In 2024, Orleans also passed a bylaw prohibiting the use of pesticide application on residential properties with some exceptions.
• In 2024, Wellfleet and Provincetown passed bylaws to reduce pesticide use.
• Additional water quality improvement success stories can be found on the Cape Cod Commission’s website.

Finally, ecological restoration projects provide benefits for water quality as well as ecological benefits for fish and wildlife habitat. There are numerous ongoing wetland and riverine restoration projects on Cape Cod, including but not limited to the Herring River in Wellfleet, Frost Fish Creek in Chatham, and Jones Lane in Sandwich. Additionally, APCC was awarded $15 million through the National Oceanic and Atmospheric Administration (NOAA) Transformational Habitat Grant to fund planning and/or implementation of wetland and riverine habitat restoration in Weir Creek Salt Marsh (Dennis), Oyster Pond Salt Marsh (Falmouth, West Falmouth Harbor), Hinckleys Pond (Harwich), and Red Brook and Quashnet River (Mashpee).  Several other restoration projects that are completed include Parkers River tidal restoration, Childs River freshwater wetland restoration, Coonamessett River restoration, Sesuit Creek salt marsh restoration, Three Bays stormwater remediation project, and Stony Brook salt marsh and fish passage restoration. APCC’s Ecosystem Restoration Program is involved in many of these projects and provides Cape Cod communities with assistance in planning and implementing successful restoration projects. For more information on restoration projects on Cape Cod, visit APCC’s website.

Maps

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