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Aquatic Connectivity and Barrier Removal (Culvert & Dams)

Fish and many other organisms use rivers and streams as pathways to move between feeding, nursery and breeding grounds. Long stretches of connected stream habitat can be resilient to changes in climate and land use. Dams and many culverts are blocking those pathways and dramatically shrinking the habitat available. At the same time, dams and culverts that are too small affect hydrology, sediment transport, and water quality of streams, and cost money for towns, counties and the state to replace and maintain.

Road-stream crossing in Rensselaerville, NY
This road-stream crossing in Rensselaerville, NY is a significant barrier to organisms that are heading upstream (Photo A.Meyer)

What are we doing?

The Hudson River Estuary Watershed has more than 1500 dams, and likely more than ten thousand culverts. The Hudson River Estuary Program and many partners are working towards restoring free flowing tributaries to the Hudson River. Several projects are helping to prioritize which aquatic barriers are the most detrimental to our fish and communities, so we can focus our limited resources at the most beneficial locations. See the Aquatic Barrier Map below for regional and location-specific information about the culverts and bridges we've assessed.

Alewives in the Wynants Kill
Alewives in the Wynants Kill

HERRING RETAKE THE WYNANTS KILL! In the City of Troy, the first barrier to fish was removed on the Wynants Kill in early May, and in less than 5 days, alewives had retaken the tributary as spawning habitat for the first time in 85 years. The City of Troy got a tributary restoration grant from the NYSDEC Hudson River Estuary Program and removed the barrier, reconnecting over a quarter mile of spawning habitat for herring, and improving habitat for many other species including American eel. This barrier had been identified by WRI staff as a critical barrier to migratory and resident fish, as well as many other aquatic and riparian organisms.  Watch videos of the herring run here Alewives in the Wynants Kill and Alewives and the concrete channel of the Wynants Kill.

Who are our partners and audience?

Municipalities, county governments, and the State DOT all own and maintain culverts. NYS DEC, North Atlantic Aquatic Connectivity Collaborative, Cornell Cooperative Extension, Soil and Water Conservation Districts and conservation organizations like The Nature Conservancy, Riverkeeper and Trout Unlimited have helped assess and prioritize culverts.

What have we found?

Use our Interactive Aquatic Connectivity map to get details about aquatic barriers.

This map includes the infrastructure that we have assessed and the barriers that have been identified. Species would benefit if they could get passed the Biologically Important Barriers. We acknowledge that some of the dams included in this research are important resources, and there is no attempt to remove dams that have high community value. Check the popup information on the Culvert Prioritization Project locations for the Barrier Evaluations. These projects have shown that species would benefit if they could get passed the Biologically Important Barriers and the Culvert Project locations with poor Barrier Evaluations. The popups also include information on modeled capacity for storm events at the Culvert Prioritization Project locations. 

Dam at head of tide on Mill Creek in Rensselaer, NY
This dam is at the head of tide on Mill Creek in Rensselaer, NY. Habitat for migratory fish, such as herring and American eel, has been substantially reduced by barriers in Hudson River tributaries. (Photo A.Meyer)

Research on these topics 

The full report on the Biologically Important Barriers project can be found here. Our culvert prioritization project in 2013 and 2014 assessed more than 1000 culverts, and modeled which were too small to pass flood flows and identified which were barriers to aquatic organisms. Very detailed information is available about each culvert in the North Atlantic Aquatic Connectivity Collaborative's database; see the popups for links to that website. More information at: