Watershed Protection Standard (WPS) Toolkit
What is the Watershed Protection Standard (WPS)?
The WPS is a stormwater design standard that protects and restores water resources. It applies to sites being developed or redeveloped. Under the WPS, sites must be designed to achieve natural, pre-development levels of groundwater recharge, which replenishes aquifers and prevents increases in off-site runoff and pollution. WPS compliance is measured through meeting a required runoff reduction volume, which depends on pre-development hydrologic soil conditions.
Implementing the WPS is practical when designers use smart strategies for site layout and stormwater control measure design. Thus, the WPS also requires an approach to site design that includes the following key strategies:
- Minimize impervious cover.
- Disconnect impervious cover.
- Preserve natural areas.
- Infiltrate wherever possible.
- Manage runoff as close to its source as possible, such that stormwater controls are distributed and natural drainage patterns remain intact.
- Place stormwater controls in soils with the greatest infiltration capacity and place impervious cover in soils with the poorest infiltration capacity.
The WPS offers alternative requirements for sites with conditions that make infiltration infeasible.
Where did the WPS come from?
The WPS was developed through years of research by the Environmental Protection Agency (EPA), which found that each new project, even when held to current Massachusetts and Rhode Island stormwater design standards, incrementally degrades watershed hydrology and water quality. The research also determined the specific recharge and pollutant reduction values that, if met for a project, would attain pre-development conditions on an average annual basis. These values were determined using long-term continuous simulation modeling based on a 29-year rainfall record and serve as the basis of the WPS.
The WPS Toolkit was developed in 2025 by VHB in close collaboration with the University of New Hampshire Stormwater Center and the Southeast New England Program (SNEP) Network. During toolkit development, the project team received advisory input from the SNEP Low Impact Development & Nature Based Solutions Strategy Team and representatives from the Massachusetts Department of Environmental Protection and Rhode Island Department of Environmental Management.
The Watershed Protection Standard Toolkit:
The WPS Toolkit Factsheet provides a summary of the WPS Toolkit.
Downloadable Links:
WPS Toolkit Factsheet
The WPS Toolkit Promotional Handout explains the WPS, its benefits, and the research behind its development. It is primarily intended for municipal staff, municipal officials and the public.
Downloadable Link: Promotional Handout
The regulatory language can be used by municipalities to adopt the WPS. It is intended to be incorporated into a municipality’s existing regulations or implemented in tandem with a model bylaw and associated regulations, which are also provided.
Downloadable Link: Regulatory Language for Adopting the Watershed Protection Standard
The WPS Toolkit Checklist is a complementary document to the template regulatory language to help a municipal reviewer assess a project’s compliance with the WPS.
Downloadable Link: WPS Compliance Checklist
The Site Examples Document provides real-world site examples that demonstrate site layout and stormwater treatment techniques that bring the site into compliance with the WPS. It is intended for designers as well as municipal staff. It consists of a cover sheet and six 11×17 inch sheets, each displaying a three dimensional model of a real site design that meets the WPS and annotations to demonstrate how each site meets the WPS.
Downloadable Link: Site Examples
Watershed Protection Standard Calculator quantifies the goal of stormwater runoff depth to treat through SCM’s from the areas of the site replaced by impervious cover.
Download the calculator here: https://scholars.unh.edu/stormwater/130/
Visit the UNH Stormwater Center Website for additional resources: https://extension.unh.edu/stormwater-center/ms4-resources
More information about the development of the WPS Toolkit can be found in the Project Summary.