Integrated Lists of Waters & Related Reports

Approved lists of impaired waterbodies in Massachusetts.

The federal Clean Water Act (CWA) requires states to submit reports on the status of their waterbodies every two years. These reports are called "Integrated Lists of Waters" ("Integrated Reports"). After a public comment period, MassDEP submits these reports to the US Environmental Protection Agency in fulfillment of the CWA's reporting requirements. Waters listed as impaired are prioritized for the development of Total Maximum Daily Loads (TMDLs), watershed-based plans, or other corrective actions.

Final 2018/2020 Integrated List of Waters

On February 2, 2022, MassDEP received EPA approval of the Final 2018/2020 Integrated List of Waters (§303(d) list). For the combined 2018/2020 reporting cycle, MassDEP focused its efforts on the assessment of the aquatic life use for the 18 watersheds that were not completed in the 2016 Integrated Report (IR) cycle. Quality-controlled data submitted to DEP prior to the pre-established deadline of 11/1/2019 were considered, relative to the 18 watersheds assessed. Data submitted after the 11/1/2019 deadline were not considered for the 2018/2020 IR but will be considered in a subsequent cycle.

EPA has approved states combining IR cycle submissions, and MassDEP coordinated with EPA-Region 1 to seek approval for combining the 2018 and 2020 reporting cycles into one submittal. 

For a geospatial view of DEP’s latest assessment and listing decisions contained in the 2018/2020 IR, open the MassMapper application and select “Regulated Areas” to access the data layers for the “DEP 2018 Integrated List of Waters…”: rivers, lakes/estuaries, and watersheds.

The final 2018/2020 IR package consists of 26 files:

  • Narrative IR document containing summary tables for each integrated list category
  • IR Appendices 1-5 document, presenting the following additional information, including the proposed changes from the 2016 IR:
    • List of EPA-approved “Actions”
    • Assessment units and integrated list categories presented alphabetically by major watershed
    • Impairments added to the 2018/2020 integrated list
    • Impairments removed from the 2018/2020 integrated list
    • Impairments changed from the prior reporting cycle
  • IR Appendices 6-24 are watershed-based Assessment and Listing Decision Summaries for each of the 18 focus watersheds, as well as for Mount Hope Bay. Each document contains the supporting data and rationale for delisting decisions.
  • IR Appendix 25 provides a summary of changes between the Draft and Final versions of the Massachusetts Integrated List of Waters for the Clean Water Act 2018/2020 Reporting Cycle
  • Summary of changes worksheet (with filter ON; can be used to search for changes from the 2016 to 2018/2020 IRs, based on watershed, waterbody, AU category, impairment cause, etc.)
  • Response to Public Comments document 
  • EPA Review Document
  • EPA Approval Letter

Table of Contents

Final 2018/2020 Integrated List of Waters

Prior Integrated Lists of Waters

US EPA TMDL Information

MassDEP Publicly-owned Treatment Works Nitrogen Evaluation Study

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