Water Quality Assessments

Look here for reports on the condition of watersheds in Massachusetts.

MassDEP's Watershed Planning Program (WPP) conducts monitoring and assessment activities and reports its findings to the United States Environmental Protection Agency (USEPA) and the public as required by the federal Clean Water Act (CWA). Water quality assessments are conducted to evaluate the ecological and recreational ("fishable/swimmable") condition of Massachusetts’ surface waters.

Reporting Requirements

Sections 305(b), 314, and 303(d) of the CWA direct states to monitor and report on the quality of their surface waters and whether they support designated uses. The WPP fulfills these monitoring and reporting requirements and evaluates the support of uses designated in the state’s Surface Water Quality Standards (SWQS) Regulations (314 CMR 4.00). The designated uses include aquatic life (such as fish, other aquatic life, and wildlife); fish consumption; public water supply; shellfish harvesting; primary (e.g., swimming) and secondary (e.g., boating) contact-recreation; and aesthetics. Assessment and listing decisions are combined in biennial Integrated Reports to EPA. To view DEP’s latest 305(b), 314, and 303(d) decisions geospatially, you can use WPP’s Water Quality Data Viewer (under the Integrated List of Waters view) or the MassMapper application (select “Regulated Areas” to access the most recent data layers for the DEP Integrated List of Waters).

Data Used in Assessments

Validated water quality monitoring data are provided by the WPP monitoring program (WPP Monitoring Data).  Additionally, quality-assured data are provided from watershed associations and other outside groups (External Data Submittals).  These data, along with other state and federal agency data, are used by the WPP to assess and report on the state’s surface water quality conditions.

Assessment and Listing Methodology

The Massachusetts Consolidated Assessment and Listing Methodology (CALM) Guidance Manual (see Additional Resources below) describes how data are used to assess surface water quality conditions, and the process used to identify causes and sources of impairment. It also describes the categorization of the assessed waters as to whether they meet designated uses. Waters that are impaired for one or more uses due to pollutant(s) are listed on the 303(d) “List of Impaired Waters” (“303(d) List”).

The CWA requires states to submit reports on the designated-use-support status of their water bodies every 2 years. These "Integrated List of Waters" reports (IR) combine the CWA reporting requirements of sections 305(b) (“Summary of Water Quality”) and the 303(d) List. Category 5 of the IR is assigned to the surface waters on the 303(d) List that require restoration using cleanup plans, or Total Maximum Daily Loads (TMDL). The 303(d) List is subject to public review and comment and must be approved by the US Environmental Protection Agency.

2022 Consolidated Assessment and Listing Methodology Guidance

2018 Consolidated Assessment and Listing Methodology Guidance

2016 Consolidated Assessment and Listing Methodology Guidance

2012 Consolidated Assessment and Listing Methodology Guidance

Statewide Statistical Reporting

In order to assess the quality of Massachusetts’ water resources, the MassDEP Watershed Planning Program (WPP) conducts both targeted and probabilistically-based surface water monitoring. Targeted monitoring approaches are by design limited to specific locations, and typically cover a small percentage of the total waters in the state. To enable reporting on the condition of all waters in the state, WPP uses probabilistic monitoring strategies to assess rivers, lakes and estuaries. The overall goal of this strategy is to provide an unbiased and statistically valid assessment on the condition of selected designated uses (e.g., Aquatic Life Use and Recreation Use) in all waters of the state and the potential stressors impacting those uses. The use of probabilistic monitoring is based on the principle that the quality of waters in a target population can be statistically estimated or inferred with a stated level of certainty by monitoring a random subset of the waters in the target population. In 2011, the Massachusetts Probabilistic Monitoring & Assessment Program (MAP2) was initiated with wadeable rivers and streams as the first water resource type assessed. The summary report for the MAP2 wadeable rivers and streams project is now available. From 2016-2018, a statewide probabilistic monitoring project was conducted for MA lakes and ponds. A summary report for the MAP2 lakes and ponds project will be available soon. WPP is currently engaged in a multi-year probabilistic monitoring project for coastal water resources (2020-2023).

Probabilistic Assessment of Wadeable Rivers And Streams 2011-2015

Macroinvertebrate Indices of Biotic Integrity (IBI)

MassDEP has developed new macroinvertebrate Indices of Biotic Integrity (IBIs) that will address the needs of MassDEP to assess multiple types of perennial, wadeable streams using biological indicators. IBIs were calibrated using a reference condition approach to identify characteristics of relatively undisturbed biological communities. Use of these IBIs will improve MassDEP’s diagnostic ability to identify degradation in biological integrity and water quality. Two IBIs were developed for high-gradient (riffle-dominated) streams in Massachusetts: one for the Western Highlands and another for the Central Hills. These two regions represent the natural variability of stream conditions found throughout the state. In addition, a single IBI was developed for low-gradient streams and is applicable state-wide. These IBIs will be included in the 2022 Consolidated Assessment and Listing Methodology (CALM) and will be used to determine the aquatic life use support status of wadeable streams for reporting under sections 305(b) and 303(d) of the Clean Water Act.

See below for four individual reports that include more detail pertaining to the development and calibration of the IBIs for low- and high-gradient streams. For additional information that supported the IBI development process, please contact James Meek at 508-767-2863.

Development of an Index of Biotic Integrity for Macroinvertebrates in Freshwater Low Gradient Wadeable Streams in Massachusetts

Development of Indices of Biotic Integrity for Assessing Macroinvertebrate Assemblages in Massachusetts Freshwater Wadeable Streams

Establishing Numeric Biological Condition Thresholds

Calibration of Indices of Biotic Integrity for 300-organism macroinvertebrate riffle habitat samples in Massachusetts freshwater wadeable streams

Additional Resources

Water Quality Assessment Reports by Watershed (WPP survey years 1997 through 2004)

Water Quality at DCR State Beaches

  • Final Beach Water Quality Report
    The complete report issued to the Senate and the House of Representatives on the water quality at beaches under the care and control of the Department of Conservation and Recreation, 2008-2012. This special report was submitted in fulfillment of House Bill No. 4384.
  • Final Beach Water Quality Report
    Main body of the report on the water quality at beaches under the care and control of the Department of Conservation and Recreation, 2008-2012.
  • Appendices to Beach Report
    Appendices to the Beaches Water Quality Report, 2008-2012.

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