Overview
WRI supports the restoration of aquatic connectivity in waterways statewide through the removal of obsolete dams and replacement of undersized or improperly installed culverts at priority locations. These infrastructural changes will improve water quality, reduce flood hazards, promote asset management and facilitate aquatic organism passage to foster healthy populations of recreational, commercial, migratory and resident fish species. WRI's Aquatic Connectivity research and outreach program supports the Hudson River Estuary Program Action Agenda, the Great Lakes Action Agenda, and established statewide priorities.
Major Accomplishments
Topic Area 1: Barrier Inventory and Prioritization
Context
Restoring stream ecosystem integrity by removing unused or derelict dams has become a priority for watershed conservation in New York and globally. However, efforts to restore connectivity are constrained by prioritization frameworks that overlook critical social criteria or rely on inventories that do not include smaller unmapped riverine dams. WRI conducted research to help address these major roadblocks for dam removal efforts.
New Findings
Machine Learning
A research team led by Brian Buchanan (WRI) developed and tested a machine learning approach to identify unmapped dams using a combination of publicly available topographic and geospatial habitat data. Unmapped dams were prevalent throughout the tested watersheds in the Hudson Valley and Great Lakes regions. Existing dam inventories underestimated the true number of dams by ~80-94%.
Literature Review
Seth Lutter (WRI) authored a systematic literature review of social science research related to dam removals, and identified how social considerations can be better incorporated into dam removal planning.
Culvert Model
Jared Popoli (WRI) and Ben Houston (Groundpoint Engineering) advanced culvert modeling efforts through the state, a key step toward creating more flood resilient road-stream crossings.
Future Research
WRI plans to continue expanding ghost dam inventory work to more watersheds throughout the state, and to develop and apply social science criteria to dam removal planning frameworks in New York. The Institute's work on culverts will similarly focus on expanding culvert inventory tools, access, data, and modelling efforts statewide.
Topic Area 2: Ecological Research on Barrier Removals
Context
The ecological benefits of low-head dam removals have been suggested but not well established in the scientific literature (e.g., Tonitto & Riha 2016). WRI funed several research projects to evaluate ecological outcomes of barrier removal for fishes and macro-invertebrates.
New Findings
Macro-invertebrates
Jeremy Dietrich and Pat Sullivan (Cornell) have investigated the changes in macroinvertebrate communities, in-stream substrate composition, and stream channel morphology between upstream impoundment and downstream tail-reach locations at barrier removal sites across New York State. They found that ecological recovery may happen within 3-years post-removal, and that upstream post-removal invertebrate richness could increase as much as 8-fold, as natural hydrology, sediment transport, and aquatic connectivity is restored.
Fishes
Liam Zarri and Alex Flecker (Cornell) assessed the impacts of dams on the genetic diversity of red-breasted sunfish, a native non-migratory fish species. Their results suggest that dams in the uppermost reaches of the watershed have the greatest impact on population differentiation and population structure for redbreast sunfish. While downstream dams are critically important to remove for anadromous species such as lamprey, salmon, and shad, upstream dams may cause the greatest conservation threats to small resident fishes.
Future Research
While ecological conditions are often unique site-to-site, WRI is interested in examining the broader role landscape context plays in influencing dam-removal restoration outcomes. As additional dam-removal monitoring sites are established, correlating ecological recovery metrics to landscape attributes may provide predictive capacities to optimize use of removal resources towards candidate sites which provide maximal conservation gain.
Topic 3: Outreach and Coordination
Context
WRI seeks to advance aquatic connectivity implementation efforts through public outreach and coordination of connectivity experts across the state. With many different organizations and individuals working on the topic in New York, WRI is uniquely positioned to serve as a facilitating organization and source of expert knowledge.
Progress
Statewide Working Groups
WRI co-hosts two monthly state-wide working groups on the topics of dam removal and culverts. These groups bring together researchers, managers, and advocates to discuss research results, funding opportunities, and outreach efforts.
Dam and Culvert Outreach
WRI staff worked in partnership with DEC to produce a new video on how culverts and dams impact flood risk and fish habitat. The video demonstrates the importance of reconnecting rivers for fish and climate resilience, showcases strategies for upgrading ("rightsizing") culverts and removing aging dams, and highlights work being done in the Hudson Valley.
Dam Safety Story Map
With FEMA funding, Roy Widrig (NY SeaGrant) partnered with WRI to conduct a literature review of dam safety outreach material for residents, municipalities, dam owners and recreationists. A Story Map website was also created, presenting case studies of dam failures and removals in the Northeast US.
Future Research
WRI aims to continue efforts to develop and deliver outreach on aquatic connectivity statewide. Providing inventory data to the public is another key goal. Centralizing statewide road stream crossing data such as aquatic organism passage, culvert capacity, culvert condition for public use will help municipalities evaluate existing impacts, potential benefits, and rough design information for grant applications and project planning.
Funded Projects
Seth Lutter (WRI), Integrating Social Considerations into Hudson River Estuary Dam Removal
Jeremy Dietrich (WRI), Advancing Dam Removal Science in the Hudson Estuary and Great Lakes Basins Through Research and Dissemination
Jared Popoli (WRI), Road Stream Crossing Assessment & Prioritization
Tracy Brown (Trout Unlimited), Great Lakes Aquatic Connectivity and Stream Resiliency in the Genessee and Black River Watersheds
Cornell Cooperative Extension (Dutchess, Columbia, Greene), Road Stream Crossing Management Plans
Seth Lutter (WRI), Publication: Social Considerations for the Removal of Dams and Other Aquatic Barriers
Jeremy Dietrich (Cornell University), Report: Ecological Monitoring of Barrier Mitigation Projects in the New York State Portion of the Great Lakes Watershed
Roy Widrig (New York SeaGrant), Report: Dam Safety in the Northeast & Great Lakes. FEMA Cooperating Technical Partners Project.
Cornell Cooperative Extension (Dutchess, Columbia, Greene), Road Stream Crossing Management Plans
Jeremy Dietrich (Cornell University), Report: Ecological Monitoring of Dam Removal Projects in the NYS Portion of the Great Lakes Watershed
Jeremy Dietrich (Cornell University), Report: Ecological Monitoring of Dam Removal Projects in the Hudson River Estuary
Libby Zemaitis (WRI/DEC), Outreach Video: Dams & Culverts: Reconnecting Our Waterways
Cornell Cooperative Extension (Dutchess, Columbia, Greene), Road Stream Crossing Management Plans
Ben Houston (Groundpoint Engineering), Report: Culvert Model Program 2021
Brian Buchanan (WRI), Publication: Ghost Dam Analysis
Alex Flecker (Cornell University), Publication: Evolutionary Restoration of Fishes following barrier removal in New York
Jeremy Dietrich (Cornell University), Report: Hudson Tributary Dam Removal
Cornell Cooperative Extension (Dutchess), Road Stream Crossing Management Plans
Research Objectives 2021-2024
- Identify previously un-inventoried dams and contribute to a basin-wide dam inventory to assist with aquatic connectivity restoration and assessment throughout the Hudson watershed. (ONGOING)
- Conduct a systemic review of existing literature on key social barriers to aquatic connectivity restoration. (COMPLETE)
- Implement a dam barrier mitigation analysis to identify optimal strategies to improve aquatic connectivity restoration given limited restoration budgets and on-the-ground social obstacles to barrier mitigation. (ONGOING)
- Establish the potential ecosystem impacts of barrier mitigation for water quality, aquatic life, and waterbirds. (ONGOING)
- Evaluate sediment and nutrient load reduction benefits of culvert enhancements to include in watershed management planning. (ONGOING)
- Audit existing barrier removal outreach practices and identify strategies to improve the reach and effectiveness of communication with Hudson River/Great Lakes stake holders. (ONGOING)
- Research fish demographic and genetic fragmentation by in-stream barriers, and compare the removal of culverts and dams in regard to evolutionary restoration and genetic diversity. (COMPLETE)
- Support NAACC NY strategies to promote assessments and enhancements in the Great Lakes basin by coordinating trainings in unassessed areas, outreach to municipalities, and leveraging funding. (ONGOING)
Research Objectives 2025-2028
- Continue to identify un-inventoried dams to assist with aquatic connectivity restoration and assessment statewide.
- Development of social variables for integration into an aquatic barrier prioritization tool/database of stream barriers for mitigation in the Hudson River watershed.