Aquatic Barrier Prioritization


What is the Aquatic Barrier Prioritization app?


The Aquatic Barrier Prioritization app can be used to assess and prioritize in-stream barriers to fish passage, including dams and poorly functioning road-stream crossings, for removal or upgrade.

Main functions:

  • Explore the expert-developed consensus prioritizations which assess barriers for the potential benefit that could be realized to key fish species, including migratory fish and brook trout, if removed or bypassed
  • Visualize the performance of each barrier across a range of ecological metrics to gain an understanding of what drives a barrier to be a high or low priority for improved passage
  • Run custom analyses to identify priority fish passage projects that reflect a user’s objectives, for example, for a given species or in a sub-geography

    Before and after images of the Simkins Dam removal on the Patapsco River in Maryland. Photo Credit: Mary Andrews, NOAA

Who should use it?

The fish passage restoration community is the primary user group for this app.  This group includes biologists and fish passage coordinators from state and federal fish and wildlife agencies, restoration staff with non-profits, and academia.

How does it work?

The App is split into three distinct sections.  The “At-A-Glance” section provides a broad overview of the state of aquatic connectivity in the study area.

The “Explore” sections provides users with an interface for exploring the expert-driven consensus prioritization results.  In this section, barriers in the map are colored based on the potential benefit that could be realized for target species if the barrier were removed or bypassed.  Clicking on a barrier displays the values for the ecological metrics which underlie the prioritization and which can help a user understand why a high priority is a high priority.  Links are available for each metric to describe the metric.

The “Custom Analysis” section is targeted at experienced users who want to go beyond the consensus prioritizations to develop a prioritization for their specific objectives.  In this section, users can select and weight ecological metrics, define a sub-geography (e.g. town, subwatershed) for the analysis, and model the removal of barriers to assess the impact of a potential project on the surrounding priorities.

What are the strengths and limitations?

App Strengths:

  1. Provides a framework for prioritizing amongst the many thousands of potential barrier removal / upgrade projects
  2. Leverages expert knowledge via consensus prioritizations
  3. The results and tool are flexible: agnostic of any specific action (e.g. barrier removal, fish passage construction), ability to run custom analyses, can be supplemented with site-scale information but it is not required

App Limitations:

  1. Not well suited to identifying groups of projects, though once identified, groups of projects can be assessed together
  2. Generated using regional-scale data, so important site-specific factors are not included
Where is it being used?

Version 2 of the App has been deployed for the Northeast U.S. ( and Chesapeake Bay watershed ( while the latest version of the App, version 3, was developed for the Penobscot River watershed in Maine (  In these geographies, the app has been used to identify potential fish passage restoration projects, to support funding requests, for local communication and outreach efforts, and to help inform funding allocation decisions.

Who helped develop it?

The app was developed by Erik Martin at The Nature Conservancy in Maine.  The layout of version 3 of the app was designed by SpatialDev (Kim Kearns and Naomi Menahem), informed by The Nature Conservancy in Maine’s Freshwater Team and implemented by Erik Martin.