Session 1 – Restoring Native Migratory Fish Passage at Stream Barriers

Wednesday, March 31, 10:00AM-12:00PM

Maranda Nemeth, Atlantic Salmon Federation
Michael Sears, Innovasea

Dams and other barriers are a leading cause to the decline of native migratory fish populations. These barriers block or restrict the necessary movement of these species to access critical habitat to spawn and rear. Since the removal of Edwards Dam 20 years ago, many projects have successfully resolved these barriers through dam removal, technical and nature-like fishways, and culvert upgrades. This session will discuss the challenges these projects present and highlight the successes of several fish passage projects that have restored native sea-run fish runs to communities across Maine.

Session Schedule


* Speakers are indicated in bold font.

Fishways and Dam Removals: Recent Successes and Upcoming Projects from the Maine Dept. of Marine Resources

Casey Clark, Sean Ledwin, Gail Wippelhauser, Micheal Brown, Nate Gray
Maine Department of Marine Resources, Augusta, ME

The removal of Edwards Dam and the construction of fishways at many of the mainstem hydroelectric projects on Maine’s large rivers reopened the migratory pathway for many diadromous species. Along with these larger barriers, many small dams and other obstructions have been removed to allow access to critical spawning and rearing habitat. The Maine Dept. of Marine Resources has been an active partner in many of these restoration projects over the last several decades. Recent restoration projects include the construction of the Lower Togus Pond Fishway (Togus Stream) and removal of the Mill Street Dam (Sabattus River). Looking forward, MDMR is embarking on a campaign to restore passage to Sabattus Lake from Androscoggin River. We will discuss the lessons learned from successful projects, some of the challenges we face with our upcoming projects, and celebrate the partners that have helped us along the way.

Design of a Nature-like Fishway Optimized using CFD Modeling

Ben Mater1, Greg Allen1, Stephen Amaral1, Barry Stemm2
1. Alden Research Laboratory, Inc., Holden, MA
2. Sappi North America, Inc., Boston, MA

This talk is available on video.

Fish passage is being implemented at Saccarappa Falls on the Presumpscott River in Westbrook as part of the decommissioning of the Saccarappa Hydropower Project. The project will open up approximately 5 miles of habitat and access to tributaries between Saccarappa and the Mallison Falls Hydropower Project. Saccarappa is the second dam on the river approximately ½ mile upstream of the Cumberland Mills dam, which installed fish passage in 2013. The decommissioning of the hydropower project includes removing the project spillways, powerhouse and related structures, filling of the tailrace and fish passage improvements. A double Denil fish ladder over the lower Saccarappa Falls and Nature-like fishways (NLF) over the upper Saccarappa Falls are being implemented to improve fish passage after decommissioning. This presentation will provide an overview of the project and focus on the optimization of the NLF design using computational fluid dynamic (CFD) modeling. A unique process was employed to accurately model large-scale channel roughness within the three-dimensional model. The design was optimized through an iterative process of reviewing CFD simulation results of depth and velocity. An evaluation of fish passage effectiveness was then performed using results from the CFD simulations, wherein likelihood of passage by fish size was determined based on the swim speeds and endurance.

Maine Aquatic Connectivity Restoration Project

Ben Naumann1, Eileen Bader Hall2
1. USDA-Natural Resources Conservation Service, Bangor, ME
2. The Nature Conservancy, Brunswick, ME

The Natural Resources Conservation Service (NRCS), The Nature Conservancy (TNC), and many federal, state, tribal and NGO partners are collaborating on a Regional Conservation Partnership Program (RCPP) project “The Maine Connectivity Restoration Project,” to reconnect fractured stream habitat centered around the distinct population segment of Atlantic salmon. The project objective is to reconnect at least 50 stream miles of aquatic habitat over the five-year project, with the overarching goal to further change the perception that road stream crossings only move water by implementing examples of best practices for designing crossings to provide aquatic organism passage. This presentation provides an overview of the collaborative conservation effort, the successes achieved, and the lessons learned in the first half of the project. The presentation also provides valuable insights to partners interested in collaborative conservation funding mechanisms for addressing aquatic resource concerns.

Restoring Fish Passage at Head Tide Dam, Sheepscot River

Michael Burke1, Maranda Nemeth 2
1. Inter-Fluve, Inc, Damariscotta, ME
2. Atlantic Salmon Federation, Brunswick, ME

The Head Tide Dam is a concrete gravity dam structure built in 1916 to power a mill after the previous wooden dam washed out several years earlier. After the close of the mills in 1949, the gates were removed opening the western abutment to active river flow. In the 1950’s, the eastern abutment was cut out to improve fish passage. Ultimately, these openings caused flow constriction, created a velocity barrier, and led to significant fish passage delays for Atlantic salmon, river herring, and American shad. A collaborative project was developed by the Town of Alna, the Atlantic Salmon Federation, and their partners to improve fish passage and also enhance the site. Dam removal was not a legal option because of a deed covenant on the Head Tide Dam thus the partners evaluated several alternative designs and utilized hydraulic modeling results and photo rendering as communications tools. The process facilitated eventual unanimous support to modify the western abutment and the Head Tide Dam Modification Project was completed in Fall 2019. The implemented project is the culmination of several decades of evaluation, discussion and planning by a variety of engaged groups. The presentation will provide an overview steps leading to the final project and explore the relationship of this site to the broader multi-site restoration initiative within the Sheepscot watershed by ASF and their partners.

Design and Construction of the Springs Dam Nature-like Fishway on the Saco River

Ralph D. Nelson, Jr., P.E.
Senior Civil Engineer, HDR, Portland, ME

The Cataract Hydroelectric Project, Licensed by the Federal Energy Regulatory Commission (FERC) is located in the lower Saco River in Saco and Biddeford Maine.  The Cataract project was constructed in 1938, and consists of a series of four dams across two islands in the Saco River in Biddeford and Saco Maine. The Cataract Dam and the West Channel Dam are located at the head of the tide at Factory Island. The upstream dams at Springs Island also has two component dams; the Springs Dam and the Bradbury Dam. The Springs Island dams impound storage for operation of the downstream hydroelectric generating station located at the Cataract dam.

A FERC license issued in 1989 required fish passage at the Springs and Bradbury project dams.  A 1994 Fish passage agreement with the State and Federal Resource Agencies resulted a 1997 fish passage construction project at the dams. A 2007 Saco River Fish Passage Settlement Agreement, addressing passage on the lower Saco River, included a requirement for further evaluation or modification of the 1997 lock and lift passage systems at the Bradbury and Springs.  The 1997 lock and lift passage systems provided effective upstream passage for river herring and Atlantic salmon, but had not been as effective at passing American shad. The 2007 Agreement required modification of the existing systems or the installation and operation of a Denil-type fishway at the Springs Dam. Brookfield authorized HDR to begin design efforts starting with an evaluation of fish passage alternatives, and development of concepts and concept drawings for various alternatives.  Ultimately, through negotiation with the State and Federal Agencies, the NLF concept was approved for final design and construction.

Construction of the Springs Dam Nature-like Fishway (NLF) was completed in 2019.  The construction of the NLF enhances volitional fish passage of target species (Atlantic salmon, American shad, Herring, American eel and other species) within the river. Design of the structure involved unique design challenges, including accommodating a two-foot headpond operation range, a four-foot tailwater operational range, high flow considerations, some construction work in the wet,  modifications to the existing dam, and design for stability during flood flows. The Springs NLF is approximately 250 feet long, 100 foot wide, and was constructed by the Sargent Corporation using local materials for construction, including the use of large, locally sourced stones for creating weirs and pools and the local processing of materials for riprap and fill.

The Springs Dam Nature-like Fishway (NLF) was designed to provide volitional upstream and downstream passage and additional aquatic habitat for a wide variety of aquatic organisms and fish.  The Springs NLF will require very limited maintenance while enhancing fish passage and will have a very long service life. The project included landscape plantings, walkways and benches for public access, as well as providing vistas of the fishway along the architectural fencing; all adding to the riparian character of downtown Saco.

Question and Answer Session


  • Casey Clark
  • Ben Mater
  • Ben Naumann
  • Eileen Bader Hall
  • Michael Burke
  • Maranda Nemeth
  • Ralph D. Nelson