North Atlantic Region

Area Overview

The Penobscot River is New England’s second largest river, draining nearly one-third of the State of Maine with a watershed area of 8,570 square miles.  The river is tidal for the first 25 miles up to the former Veazie dam, which was removed in 2013.  The Penobscot River is home to 11 diadromous (sea-run) fish species, including three listed under the Endangered Species Act — Atlantic salmon, shortnose sturgeon, and Atlantic sturgeon, and represents the largest run of Atlantic salmon left in the United States.  Despite its size, the watershed has a low human population density, is largely forested, and contains many large lakes and multiple tributaries offering coldwater refuge for native salmonids like Atlantic salmon and brook trout.  The Penobscot River watershed has a rich cultural history of commercial, recreational and sustenance fishing, and is home to the Penobscot Indian Nation, who still occupies part of their ancestral homeland on Indian Island, surrounded by Penobscot waters.

Historically, the fisheries on the Penobscot River were bountiful, with an estimated 14 to 20 million alewives, 75,000 to 100,000 Atlantic salmon, and 3 to 5 million American shad.  As with many eastern rivers, dams, culverts, water pollution and overfishing contributed to an almost complete elimination of many sea-run fish species from the Penobscot River watershed.  Human activities have caused a number of other adverse impacts to the Penobscot River watershed including: reduction of fish and wildlife populations and habitat; loss of recreational opportunities, including world-renowned recreational fishing for Atlantic salmon and whitewater boating; loss of fish for tribal sustenance fishing; water quality and benthos degradation, restrictions on fish consumption, and eutrophication or undesirable algae; reduction of prey species for commercially-important Gulf of Maine groundfish; diminishment of public safety around structures like dams; and diminished resilience to the effects of climate change, including warming water temperatures and potentially increasing flood magnitudes and frequencies.

Recent work led by NOAA and other partners has resulted in significant progress on addressing habitat restoration and fish passage improvements.  These include potential benefits to ESA-listed species such as Atlantic salmon, shortnose sturgeon and Atlantic sturgeon, as well as NOAA-managed marine species in Penobscot Bay and the larger Gulf of Maine.

Aerial view of the former Veazie Dam. Photo courtesy of the Penobscot River Restoration Trust.

NOAA’s Role

  • NOAA’s Habitat Restoration Center  has provided more than $21 million in funding since 2008 for the Penobscot River Restoration Project, including the removal of the two lowermost dams on the Penobscot River, Veazie and Great Works.  Ongoing work in the watershed includes additional dam removals, the construction of fishways at the outlets of lakes that provide thousands of acres of spawning habitat for alewives, the replacement of culverts in coldwater habitat for endangered Atlantic salmon and eastern brook trout, and surveys of culverts and dams to identify additional habitat improvement projects in a strategic fashion.
  • NOAA’s Habitat Restoration Center, the Northeast Regional Office’s Protected Resources Division and Northeast Fisheries Science Centerin conjunction with a broad array of public and private partners, are conducting pre- and post-project ecological effectiveness monitoring of restoration projects such as dam removals, including fisheries and water quality monitoring.
  • NOAA’s Northeast Regional Office Habitat Conservation Division and Protected Resources Division are working to restore the full suite of diadromous species through a variety of efforts including ensuring adequate fish passage at hydroelectric dams in the basin and consulting with other agencies to minimize adverse impacts associated with coastal development.  Population models developed by the Northeast Fisheries Science Center inform performance standards for fish passage at these hydroelectric facilities.
  • NOAA programs are involved in data collection and monitoring in the Penobscot River watershed, including weather data collection and forecasts by the National Weather Service.  These include tidal predictions at Bangor, Maine and the planned implementation of a watershed recreational forecast, modeled on the popular recreational forecast for Mount Katahdin.  The Northeast River Forecast Center assisted with ice-jam modeling review and evaluation, a critical study preceding main stem dam removals, and will update flood forecasting models with recently collected river bathymetric data that was used to predict changes in water surface elevations resulting from the dam removals.
  • NOAA’s partnership with Maine Sea Grant has supported research by the University of Maine on alewives, sea lamprey and Atlantic salmon on Penobscot River tributaries, and will be supporting new research by the University of Southern Maine on habitat use by juvenile river herring in the Penobscot River watershed (in cooperation with NOAA’s Protected Resources Division and Northeast Fisheries Science Center).
  • NOAA’s Northeast Fisheries Science Center and Protected Resources Division are monitoring and evaluating the diadromous fish community in the Penobscot River estuary, including multispecies telemetry cooperatives with USGS and University of Maine, and hydroacoustics survey work with multiple partners to better understand estuary ecosystem structure and function as large scale restoration efforts proceed.

Fishing the lower Penobscot River at sunrise. Photo by Joe Dana.

Proposed Habitat Conservation Objective

Restoration of multiple diadromous species and habitat through barrier removal, including alewife and blueback herring (species of concern), endangered Atlantic salmon, endangered shortnose sturgeon, and threatened Atlantic sturgeon.  As the largest freshwater input to the Gulf of Maine, restoration of diadromous fish should also provide more prey for inshore and offshore populations of managed species (such as Atlantic cod, pollack, and haddock) in the Gulf of Maine.  These efforts will increase commercial and recreational opportunities on the river, restore the ecology of the system, and provide the NWS with improved data to enhance flood forecasting.

Potential to Fulfill Habitat Blueprint Outcomes

The Penobscot River was nominated as a candidate habitat focus area because of the strong track record of federal, state, and local collaboration in the area, the availability of baseline data on fish habitat and populations, and the active history of NOAA involvement in efforts to restore habitat for fish also benefit coastal community resiliency.  The large size of the watershed–with thousands of acres and hundreds of miles of habitat–means that restoration will benefit multiple diadromous and marine species, improve water quality, and help protect the cultural heritage and sustenance fishing rights of the Penobscot Indian Nation.  The successful removal of large dams such as Veazie and Great Works points to the enthusiasm of local communities and governments for restoration, improving habitat for people as well as fish.

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