Road Stream Crossing Assessments


Streams and roads are both linear networks and where they intersect, a structure carries the road over the stream. These structures are called road stream crossings (RSX). As an integral part of our transportation networks, RSX should be constructed to not alter the natural shape of the stream. When roads and streams cannot peacefully co-exist, flooding is more likely to occur, along with increased maintenance and significant disruptions to aquatic ecosystems.

Ulster County is committed to planning for transportation infrastructure that is safe and storm-resilient, as part of this goal, Ulster County Department of the Environment has completed multiple road stream crossing (RSX) assessment projects.

From 2016 to 2018, Ulster County Department of the Environment, partly funded by a grant from the New York State Environmental Protection Fund through the Hudson River Estuary Program of the New York State Department of Environmental Conservation, assessed all RSX on County-owned roads, and all town roads in the Sawkill Watershed (excepting the crossings in the Ashokan Watershed which were assessed by the Ashokan Watershed Stream Management Program- AWSMP). This assessment examined aquatic passability using the protocol developed by the North Atlantic Aquatic Connectivity Collaborative (NAACC).

From 2019 to 2020, Ulster County Department of the Environment, in partnership with Cornell Cooperative Extension of Ulster County AWSMP, assessed all RSX (County and Town roads) in the towns of Kingston, Saugerties, and Woodstock, as well as County RSX in the Lower Esopus Watershed. This project was funded by NEIWPCC and the NYSDEC Hudson River Estuary Program. These assessments utilized an expanded RSX assessment protocol called MOSCAP, or Multi-Objective Stream Crossing Assessment Protocol. MOSCAP was developed by the AWSMP and examines geomorphic compatibility, structural condition, aquatic passage, and flood risk. Project deliverables included detailed maps of RSX, a full dataset of RSX for each town and the County, and RSX management plans that work in concert with the dataset. Given the NAACC component, each crossing has an online entry detailing structural specifications, aquatic passage data, and photos.


The NAACC is a participatory network of practitioners united in their efforts to enhance aquatic connectivity. The NAACC project will support planning and decision making by providing tools and information on where restoration projects are likely to have the greatest aquatic connectivity benefits and resiliency benefits. All data collected is available for viewing and download at:


Road Stream Crossing Assessments

 The assessment portion of these RSX projects begins with a desktop analysis in GIS to locate streams, where streams cross a road, a point is created and named, thus generating a digital RSX that is then followed up with a field visit. During the field visit, the field crew walks upstream taking measurements and noting geomorphic indicators such as erosion and deposition. The road and structure are then examined, things like; slope, dimensions, depth, and condition are entered as data. Photos are taken, the outlet and downstream are examined, then all this information is submitted to the online NAACC database. Later, the data are downloaded and combined to give the crossing a weighted score, and when compared to other crossings can be prioritized.  


Data Creation

Beyond the field assessment elements of this project, an important additional component has been spatial data creation to support more detailed hydrologic, hydraulic, and spatial analysis. In 2015, Ulster County received a 1m LiDAR digital elevation model (DEM) data set from USGS for the entire county. We contracted with GroundPoint Technologies to process the available 1m DEM to produce a hydro-enforced 1m digital elevation model (DEM) for Sawkill drainage which can be used for advanced hydrologic modeling. GroundPoint examined the culvert capacity model that Cornell Water Resources Institute developed and adapted it to calculate polygon drainage areas for culvert points in the Sawkill drainage basin using this enhanced DEM.


Subsequently, in 2016, new high-resolution land cover data was produced for the Delaware River Basin in conjunction with the University of Vermont ( Because part of Ulster County is in the Delaware River Basin, we were provided this enhanced land cover data for all of Ulster County, not just the portions within the Delaware Basin. Using funds from this grant, we contracted with Green Infrastructure Center, Inc (GIC) to produce updated habitat cores mapping using this enhanced land cover data. Previously, in 2012, GIC had produced habitat mapping for Ulster County using older, coarser (10m NLCD) land cover data. The new higher-resolution land cover data produced a significantly more detailed core habitat assessment data set. We then used the new habitat cores data to further analyze which culverts might serve as connections between these important high-quality habitat cores. (Additional information on the Green Infrastructure Center and the New York manual featuring habitat mapping in Ulster County is available at ).


Interaction and Support to Municipalities and Other Groups


As part of these culvert assessment projects, data products and plans are produced for the County and the municipalities. Road Stream Crossing Management Plans have been produced for the Towns of Kingston, Saugerties, and Woodstock. These plans, along with maps and datasets containing information on aquatic connectivity, structural condition, geomorphic compatibility, and modeled flood risk, help the municipalities prioritize replacement projects, gain points in the NYS Climate Smart Communities Program, and have the information needed to apply for replacement funding.


Ulster County published its Lower Esopus Watershed Road-Stream Crossing Management Plan in 2020


Additional Analysis and Next Steps

Ulster County Department of the Environment will continue to assess the County’s RSX, including crossings located in the Lower Esopus Watershed. This includes town roads outside the 2019-2020 study area. As part of Ulster County’s Green New Deal, the County will continue working to inventory road stream crossings that need to be repaired and resized to accommodate storms and allow wildlife to pass through unimpeded.