Green Infrastructure Planning at Prudence Island

Prudence Island sits at the heart of Narragansett Bay, one of New England’s most important and vulnerable coastal ecosystems. At the headquarters of the Narragansett Bay National Estuarine Research Reserve (NBNERR), everyday stormwater runoff from roofs and roads posed a growing threat to groundwater, nearby habitats, and water quality in the Bay.

SMMA partnered with NBNERR to solve these challenges through a campus-wide green infrastructure planning effort. The team developed a set of nature based solutions that manage stormwater where it falls, reduce flooding, and protect sensitive coastal systems. Just as importantly, these visible interventions transform the site into a living classroom—demonstrating how thoughtful design can support climate resilience, ecological health, and education at both a local and regional scale.

Prudence Island is central to the health of Narragansett Bay.

The Reserve encompasses much of Prudence Island and sits within the largest estuary in New England, making it a critical place to protect water quality, coastal habitats, and ecological systems that extend far beyond the island itself.

The team sought to mitigate stormwater flooding at four key locations on the Reserve.

Each intervention responds to local soil conditions, shallow groundwater, and surrounding habitats, minimizing disturbance while enhancing previously developed areas of the campus.

Stormwater posed a hidden but growing risk.

Although the campus avoids floodplains and wetlands, runoff from buildings and roads was causing erosion, localized flooding, and downstream impacts—issues expected to intensify with climate change.

SMMA developed a coordinated set of green infrastructure strategies—including bioretention areas, bioswales, and level spreaders—that capture, slow, and treat runoff on site instead of sending it downstream.

Location A

The bioretention area at Location A creates an adjacency to the classroom and research spaces, allowing close review of management and performance metrics.

Location B

The swales at Location B capture, pretreat, and transport stormwater to the adjacent bioretention basin, minimizing roadway flooding and capturing sediment.

Location C

The swales and level spreaders at Location C reduce the volume and velocity of stormwater approaching the roadway from the roof and lawn areas.

Location D

The bioswales along the side of the regraded roadway at Location D capture and treat runoff at the source, mitigating downstream flooding.

Native plantings strengthen habitat and resilience.

Carefully selected native trees, shrubs, and grasses support biodiversity, improve water quality, reduce erosion, and create landscapes that are both functional and seasonally expressive.

Spring/Summer

Late Summer/Early Fall

Fall

Winter

The project turns infrastructure into a teaching tool.

NBNERR’s mission as a “Living Laboratory” inspired solutions that are intentionally visible, helping students, visitors, and decision makers understand how stormwater management works in real time.

Students learn how to create a model for coastal sustainability. By aligning with state and federal environmental priorities, the project provides a scalable template for reducing stormwater impacts, protecting groundwater, and supporting climate adaptation across island and coastal communities.

The project succeeds in managing runoff from 4.2 acres (83% pervious and 17% impervious), with a peak flow reduction rate up to 87% during smaller storm events. Moreover, water quality storage exceeds requirements by 1.5x-6x, improving pollutant removal and infiltration capacity.

Green Infrastructure Planning at Prudence Island

Prudence Island is central to the health of Narragansett Bay.