Critical Resource Area Boundary Tool

Rev. 6/6/16

The following guidance is provided to assist property owners, licensed designers, licensed installers, and other interested parties in making an initial determination on whether an existing or proposed Onsite Wastewater Treatment System (OWTS) is located within the Salt Pond or Narrow River Critical Resource Area. The Department has created a map showing the critical resource area (CRA) boundaries that can be viewed in a web browser. The CRA map allows interested parties to view the CRA boundary superimposed on a street map or an aerial photograph.

The CRA is depicted as an orange shaded area that in most locations corresponds to the boundary of the Salt Pond and the Narrow River CRA watershed. In some locations, such as Route 1 in Wakefield, the line is shown along a roadway and may not represent the upper watershed boundary. In the latter instances, the roadway is accepted as the CRA boundary for the purposes of the OWTS Rules. In all other cases, the CRA boundary must be determined based on suitable reference points or topography on the property. In the case of existing home sites or other developed properties, DEM will generally accept the CRA boundary as referenced to a building or other clearly visible features on the property as shown on this website. In the case where no suitable references are evident, such as on undeveloped property or where the location of the CRA boundary line with respect to a proposed OWTS is not clear, the watershed boundary line must be determined in the field based on pre-development topographic contours.

Designers are instructed to represent the CRA boundary line on any proposed OWTS construction permit plan where the CRA boundary line exists on the property or within close proximity to the proposed OWTS.

To view the map, click the following link: Environmental Resource Map. When the map opens, select "OWTS Critical Resource Area" from the Contents List. You may need to open the Map Contents List by clicking on the "Show Contents" button.

You can also download the CRA boundary as an overlay for viewing using Google Earth software here.

If your septic system (existing or proposed) is located within the delineated Critical Resource Area, you are subject to the denitrification requirements in the OWTS Rules.

Contact Jon Zwarg at or (401) 222-4700 ext. 2777205 with questions.

Additional Resources