About the MassDEP TMDL viewer
The MassDEP Total Maximum Daily Load (TMDL) Viewer developed by the Watershed Planning Program provides geospatial representation of EPA-approved TMDLs, as required by the federal Clean Water Act (CWA) under Section 303(d).
The objective of the CWA is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters. As one step toward meeting this goal, each State must administer a program to monitor and assess the quality of its surface waters and provide periodic status reports to the U.S. Environmental Protection Agency (EPA). Once a waterbody is identified as impaired by a pollutant, States are required under Section 303(d) of the CWA to develop a pollutant limit, or TMDL, designed to restore the health of the impaired waterbody. Through this process States implement water quality-based controls to reduce pollutant loadings from both point and nonpoint sources and restore and maintain the quality of their water resources.
The MassDEP TMDL Viewer provides a geospatial representation of the final, EPA-approved TMDLs MassDEP has completed to date. The information reported to EPA by States is available in Assessment Total Maximum Daily Load (TMDL) Tracking and Implementation System (ATTAINS). This tracking database is the record of approved TMDLs represented geospatially in the TMDL Viewer. The representations are made with the best available data, but TMDL reports should be consulted for specific applicability of each TMDL.
The goal of the Viewer is to aid MassDEP staff, permit writers, stormwater managers, conservation commissions, watershed associations, and concerned citizens in identifying waterbody segments and their contributing drainage areas for which TMDLs have been developed. The tool allows users to search a location using an address or coordinates to display information on applicable TMDLs, pollutants of concern that were targeted, and TMDL reports.
How to use the viewer
This interactive map provides information on completed TMDLs as well as alternative TMDLs. A user guide is available here: MassDEP TMDL Viewer User Guide. A video tutorial is available here.
To start, open the TMDL Viewer. TMDLs are represented by pollutant group: Nitrogen, Phosphorus, Metals, Pathogen. Clicking the legend symbol in the upper right corner will reveal the symbology for each active layer. The layer list is also available to turn layers on or off. In the upper left of the TMDL Viewer, users can type in an address, coordinates, specific location name, or use Find My Location Tool, to quickly zoom to area of interest. Click on an area of interest to see additional information pop-up including TMDL name, link to TMDL report, approval year, TMDL pollutant, assessment unit ID, and waterbody name. One watershed can have multiple TMDLs for different pollutants. Use the arrow in the pop-up to view information for each of these overlapping TMDL reports. A quick filter button is accessible in the upper left, to easily filter by pollutant type, TMDL type or major watershed basin.
Additionally, filters are available by opening the attribute table located at the bottom of the map interface. Refer to the TMDL Viewer User Guide for more information and instruction on use of map features.
Additional Resources
Help us improve the MassDEP TMDL Viewer
If you discover errors, have questions regarding TMDLs and associated content in the TMDL Viewer or have suggestions to enhance the mapping tool, please email Matthew Reardon or Holly Brown at dep.wpp@mass.gov in the TMDL section, Watershed Planning Program, MassDEP.