2026 Maine Sustainability & Water conference

Thursday, March 26, 2026
Augusta Civic Center
Augusta, Maine

Sustainability graphic

Session G — Ecohydraulics Research and Applications in Watershed and Coastal Resource Management

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Conference Home Call for Abstracts Concurrent Sessions Poster Session Sponsors Keynote speaker ORGANIZING COMMITTEE REGISTRATION EXHIBITORS agenda

All Day Session
Piscataquis/Sagadahoc Room, 2nd Floor

Four Training Contact Hours (TCH) are available for this session from the Maine CDC Drinking Water Program. A sign-up sheet is available in the session room.

Session Co-Chairs:

The term “ecohydraulics” has grown out of interests in the interactions of hydrodynamics with water quality conditions, aquatic ecosystems, aquatic organisms and habitat, and civil infrastructure. Projects in the Northeast related to fish passage, reservoir management, flood management, aquatic habitat assessments, water cycle dynamics, pollution management, and seafood harvesting often involve interdisciplinary ecohydraulics science investigations. This session hosts presentations describing scientific studies and adaptations of knowledge to management actions in projects involving ecohydraulics investigations in freshwater and marine environments. Ecohydraulics themes of particular interest include place-based research outcomes, methods demonstration, and knowledge applications in resilience planning, aquatic habitat restoration, infrastructure design, and watershed and coastal resource management.

Session Overview

Morning Session

Afternoon Session

Session Presentations

Presenters are indicated in bold.

Morning Session

8:30AM – 9:00AM

Pathways of artificial heat pollution warming the Gulf of Maine – A compilation of research data

Roger Wheeler1, Halsey W. Snow2, Stephen Kasprzak3
1. Friends of Sebago Lake
2. Sierra Club Maine
3. Independent researcher & environmental writer

The Gulf of Maine is one of the the fastest warming regions on the planet. New analysis of NOAA temperature and precipitation data across the pan-Arctic ocean system reveals tipping point increases coinciding with dam construction in the North American and Siberian Arctic zones. Through the atmosphere, hydrosphere, cryosphere, geosphere and biosphere these dams have awakened or energized pathways of heat pollution that are changing the climate and funneling heat to the Gulf of Maine and New England. It is the goal of this presentation that attendees will gain an understanding and seek more information about:

  1. The volume of Arctic water emissions in the form of water vapor, and how this greenhouse gas is rapidly transforming the Arctic cryosphere with its sea-ice and permafrost sensitive to small increases in temperature.
  2. The physics behind Churned Atlantic Warmth (CAW) heat pollution due to high winter river discharges from reservoirs. We will cover the Neu theory of how CAW melts sea ice and warms both the coastal sea and the atmosphere.
  3. How these dams can alter weather patterns like the Siberian high plateau, and how this has been an intentional goal which has been achieved by the Russian Federation
  4. How the regulation of Arctic river flows affects ocean currents like the Labrador Current and the Gulf Stream, and their interaction, resulting in Gulf of Maine ocean warming

9:00AM – 9:30AM

Modeling Bacterial Pollution in Estuaries After High-Intensity Rainfall: A Watershed-Estuary Approach in Frenchman Bay, Maine

Taylor Bailey1, Lauren Ross2,4, Sean Smith3,4,5, Sohaib Alahmed6
1. 91, Maine Sea Grant
2. 91, Dept. of Civil & Environmental Engineering
3. 91, School of Earth & Climate Sciences
4. Senator George J. Mitchell Center for Sustainability Solutions
5. Darling Marine Center
6. Anchor QEA

Coastal watershed runoff from precipitation events can be a considerable source of bacterial contamination in estuarine water bodies. Increases in estuarine water quality impairments linked to shifts in climate conditions is a growing concern confronting coastal resource managers. Climate changes predicted in the Northeast include increases in the frequency and intensity of short timescale, episodic precipitation events that can amplify pollutant runoff rates. Knowledge about how estuaries with varied geomorphological complexity and hydraulic conditions respond to high magnitude and intense rainfall events is thereby vital to coastal resource management decision making. This work quantifies simulated outflows from nine coastal watersheds to four estuaries in Frenchman Bay, Maine, USA in response to prescribed storm events with more than 51 mm (2”) of rainfall in 24 hours. Runoff hydrographs provide boundary conditions in estuary hydrodynamic simulations to assess the extent of polluted freshwater input to the four estuaries during and after the rainfall event. We show that estuary geometry can be a major control on the duration of estuary water quality recovery after intense rainfall through evaluation of a “worst-case scenario” load concentration of fecal coliform bacteria. Estuaries that exhibit density-driven dynamics take more than one week to fully recover from 2” of precipitation in 24 h under the “worst-case scenario”. However, some portions of estuaries show relatively low susceptibility to water quality impairment due to conditions governed by estuary channel geometry. Our results imply that geomorphic attributes, such as channel constrictions, can provide useful proxy metrics to refine pollution vulnerability assessments.

9:30AM – 10:00AM

Using graph neural networks to investigate bluff erosion hazards on the coast of Maine

Samuel N. Walters (student)1, Chris Gerbi1, Peter Koons2
1. 91 School of Earth and Climate Sciences
2. 91 Climate Change Institute Emeritus

We investigate whether graph neural networks (GNNs) can identify patterns that link coastal surface topography and tidal hydrodynamics to bluff stability on the coast of Maine. Using LiDAR-derived elevation data from the Freeport, Maine area, we constructed 423 flow-routing graphs representing hillslope drainage networks that terminated at coastal bluffs. Each graph was assigned hydrodynamic data from a TELEMAC-3D tidal simulation, and the graph terminal (sink) nodes were labeled with stability classifications (stable, unstable, historical landslide) from Maine Geological Survey hazard maps. A graph convolutional network achieved 69% accuracy in distinguishing stable from unstable bluffs using graph structure and hydrodynamic data, but ablation studies revealed that a simple feedforward neural network using only three hydrodynamic variables (maximum velocity, velocity standard deviation, and tidal range) achieved 73-75% accuracy. The results indicate that for this coastal setting, simple statistical models may be sufficient for hazard assessment, though this methodology could be extended to other landslide-prone environments where multi-source geospatial data integration is needed.

10:00AM – 10:30AM

Assessment of Selected Water Quality Parameters in the Aroostook River

Nick Anderson (student), Udaya K Jayasundara
Department of Chemistry, 91 at Presque Isle

The Aroostook River located in the Aroostook County in Northern Maine is a significant freshwater source that plays a vital role in ecosystems and agricultural industries in the area. Therefore, it is important to ensure that water remains clean and healthy for consumption. To determine the quality of water, samples were collected from major townships and tested for pH, silica level, nitrate/ nitrogen level, phosphate level, and for hardness. These tests were chosen as they directly affect both nutrient level and farming industries in the area. All experiments were conducted in the 91 at Presque Isle chemistry laboratory using test kits by Lamotte Company manufactured in 2024. The tests showed some surprising variations as well as consistencies. The average pH was 6.2 ± 1.3 in all areas under the study which suggested that the river was influenced by human activities and values were below the EPA’s standard of 6.5. The average silica content was found to be 2.9 ± 0.9 ppm which was far below the EPA standard drinking quality water. However, the samples collected from Washburn area demonstrated higher silica content. The nitrate/phosphate test resulted an average of 0.31 ± 0.18 ppm which was higher than the EPA standard of 0.1 ppm. The average hardness of water was 27.4 ± 4.4 ppm which demonstrate that the water was soft. This study shows the importance of continuous monitoring of water quality to yield better human and agricultural health.

Afternoon Session

1:30PM – 2:00PM

Effects of surface water/groundwater exchange on aquatic habitat in a White Mountains floodplain

River Khoriaty (student)1, Anne Lightbody1, Ryan Omslaer1, Landon Gryczkowski2, Michael Palace1 Franklin Sullivan1
1. University of New Hampshire
2. U.S. Forest Service

The connection between groundwater and surface water through hyporheic exchange can moderate decreases in surface water flow, recharge riparian groundwater stores, and reduce summertime water temperatures. The cobble-bedded Zealand River (44.2461°N, 71.4968°W) in Bethlehem, NH, was recently restored to protect civil infrastructure, aquatic habitat, and recreation. Now, multiple anastomosing channels may augment groundwater exchange, although the extent of this gain is unknown. We installed surface and groundwater pressure transducers, allowing us to collect continuous records of water surface elevation in the river channels and floodplain during June-September 2025, which we correlated with measured stream discharge to estimate total flow volume at points along these channels. We used aerial thermal imagery, dilution gauging, temperature, and conductivity to identify sources and losses of surface water. These observations were used to develop connected groundwater and surface water flow models, which provide a reach-scale view of flow patterns within the floodplain of the lower Zealand River. Hydraulic gradients were generally stable in magnitude and direction over the study period, despite the onset of intense regional drought, suggesting that surface water provided continual recharge of groundwater, stabilizing riparian water availability. Channels with larger influxes of groundwater also exhibited temperatures up to 4℃ colder. In modern times with increasing and longer-lasting hydrologic extremes, surface water and groundwater exchange can further stabilize water levels and temperatures, as well as inform river restoration approaches due to their benefits for aquatic habitats.


2:00PM – 2:30PM

Changes to Wetland Structure, Function and Extent from Walton’s Mill Dam Removal Based on Intensive Pre and Post-Removal Monitoring

Alan Haberstock1, Maranda Nemeth2, John Burrows3, Bill Bennett4
1. PWS
2. National Oceanic and Atmospheric Administration, Fisheries Restoration Center
3. Atlantic Salmon Federation
4. US Fish and Wildlife Service Gulf of Maine Coastal Program

The Sandy River watershed in western Maine and its cold, spring-fed streams are prime habitat for wild Atlantic Salmon and co-evolved species. However, several dams have impeded access to this habitat. The Atlantic Salmon Federation and the Town of Farmington, with funding from partners, spearheaded the removal of Walton’s Mill Dam on Temple Stream to restore aquatic connectivity and floodplain wetland function while reducing flood extremes, providing recreation improvements and resolving dam repair and regulatory burdens. In compliance with MNRCP monitoring requirements, wetland and riparian surveys were conducted beginning several years before the 2022 removal and have continued through to the present (2025). Data on plant species composition and areal cover were collected by meander surveys and along fixed transects with M2 plots using a stratified random technique where each distinct wetland cover type was surveyed. Results informed adaptive management decisions such as invasive species control and supplemental seeding/planting. Following dam removal, the seed bank responded rapidly, and wetland succession was explosive, showing that natural colonization following dam removal can be an effective restoration approach. Native wetland vegetation established a 75-90% cover, protecting exposed substrates within weeks. Early colonizers like spikerush and Joe pyeweed yielded to a scrub-shrub habitat dominated by native shrubs like speckled alder and willows within two years. The presentation will review the monitoring results that documented that the dam removal directly resulted in wetland functional lift and an increase in wetland extent. This included improved riparian habitat and floodplain functions.


2:30PM – 3:00PM

Afternoon Break (Auditorium)


3:00PM – 3:30PM

Hydrologic investigations supporting multi-objective watershed management in northern Maine

Sean M.C. Smith1,2,3, Bea E. Van Dam1, 2, David J. Libby1, George K. Swenson1
1. School of Earth and Climate Sciences, 91
2. Sen. George J. Mitchell Center for Sustainability Solutions
3. Darling Marine Center, 91

Flow regime evaluations will play an important role in the development of future river corridor management strategies in northern Maine watersheds experiencing past and ongoing forest harvest activities, new demands for ecosystem services, and public interest in aquatic habitat rehabilitation projects. Information derived from river discharge time series at USGS gaging stations and outcomes from watershed hydrologic simulations provide essential support to management decision-making involving aquatic habitat, recreation, and public safety objectives. Outcomes from recent investigations in northern Maine headwater areas contextualize large-scale changes to forest cover relative to background hydrologic conditions and stream channel stability evaluations. Another example offering insight into the influence of civil infrastructure on contemporary river flows focuses on the upper East Branch Penobscot River drainage area, which receives inflow from the Allagash River watershed through the Telos Cut canal and is regulated by the Matagamon Dam. Simulations supported by measurements capture processes related to precipitation runoff generation, snowmelt, surface flow routing, and dam operations over time-periods ranging from single events to a decade at hourly time steps. The iterative approaches to data analyses and model development collectively provide a foundation for examination of flow regime outcomes relative to varied combinations of environmental conditions, watershed land-use activities, and dam operations. They also provide guidance for future investments in watershed assessments and measurement infrastructure by highlighting important data gaps and uncertainties.

3:30PM – 4:00PM

Novel Approach to Predict and Visualize Fish Passage Potential at a Large-Scale Nature-Like Fishway

Marcel Young-Scaggs1, Ellie Mason2, Michael Burke1
1. Inter-Fluve
2. Downeast Salmon Federation

In full focus among river restoration practitioners in the North-East is a need to provide connected riverine habitat for aquatic organisms, in particular, critically endangered Atlantic salmon and other co-evolved native migratory fish. Effective passage along Maine’s river corridors is essential so that migratory fish can volitionally access important spawning and rearing habitat that they need to thrive. When removing or altering barriers to support fish passage, “day-one” passage is often a project requirement, and practitioners are tasked with developing a solution that achieves this goal. When developing complicated or nuanced passage systems, like nature-like fishways, it can be a challenge to develop analyses that predict if fish passage can occur at a project site. A practitioner must combine an understanding of the biological capabilities of fish, fish behavior, and complex riverine hydrodynamics to predict passage potential at a project site. In Cherryfield Maine, the Downeast Salmon Federation, in partnership with the Town of Cherryfield, is preparing to provide fish passage at the Cherryfield Ice Dam by replacing the existing structure with a channel spanning nature-like fishway. Project implementation will restore an estimated 515 miles of riverine habitat and 2,609 acres of alewife spawning habitat in the watershed. This presentation will provide an overview of the Cherryfield Ice Dam Fish Passage Project, explore the fish passage analysis conducted for this site, and present novel integrated methods for exploring passage potential.