If you live near a stream or creek, chances are high that you live near a road-stream crossing called a culvert. These short tunnels, often pipe or box-shaped surrounded by soil, exist underneath roadways to help water move from one point to another. That movement brings other benefits, like wildlife passage and reduced flooding. When culverts are too small or damaged, they can cause problems. Fully connected streams provide cooler water for migratory and resident fish species to freely access habitat for spawning, foraging, and travel. Problem culverts not only cut off habitat access for fish and wildlife, but they can also degrade water quality, creating ideal conditions for invasive species. They also increase flood risk and disrupt other vital ecosystem services such as sediment and nutrient transportation. 

A new interactive map addresses these issues. Launched this winter by Save the Sound, Seatuck Environmental Association, and The Nature Conservancy, the Long Island Sound Road-Stream Crossing Prioritization Tool helps communities find undersized culverts in their area. This saves time and money when making repairs. It also helps prioritize which repairs should happen first when building climate-friendly structures.  

The tool scores culverts on a 1-20 scale based on four metrics: ecological impact, transportation functionality, resilience to climate, and physical condition. Users can filter factors such as location, waterbody name, and road type. Dots on a color scale from light blue to red highlight crossings in need. Darker dots show where culvert replacement or repair would bring the biggest benefit. 

The project team, led by Save the Sound’s Megan Lung, studied on-site more than 300 crossings in Westchester County and incorporated hundreds of additional crossings in Nassau and Suffolk counties. The work is not glamorous, trudging through water under sometimes dense vegetation. But it paints a strong picture of undersized culverts’ effects on the ecosystem. 

Undersized culverts are common, often built decades ago with small budgets. As a result, they were not designed to handle the current era of rising sea levels. This especially concerns coastal watersheds, like the Long Island Sound. 

At its core, the tool aims to give municipalities a starting point. 

“When anyone who wants to address aquatic connectivity with human infrastructure in the watershed—dams, bridges culverts—we want this tool to be the place to go, to start,” said Lung. “Everybody has different priorities, but we want to help get people out there and provide resources for improvement.” 

The tool developed from a previous study of crossing restoration efforts from The Nature Conservancy, who also conducted on-site studies. Funding was provided in part by a Futures Fund grant from the Long Island Sound Partnership and seeding funding from the Alexander Center for Ecological Action at Save the Sound. 

It is up to communities to decide if they want to repair the crossings. Still, the tool offers a foundation for stronger decision-making. Save the Sound has already hosted trainings for users and plans to continue expanding those efforts. Anyone who finds a barrier or undersized culvert can also report it to Save the Sound, who will add it to the map. 

The map may expand to the rest of the watershed later but is not expected in the immediate future. 

In the face of rising sea levels, Lung sees an opportunity. 

“Where land development is happening, we treat our stream as things to be conquered, not as a partner [with whom to work]. This tool provides us a better outlook for the future.” 

Find here an informational webinar to learn more.

Find the tool here to see if there are barrier or undersized crossings near you.