1. Recovery of the Penobscot River: 150 Years of Change

Morning Session (Washington/York Room, 2nd Floor)

* 2 credits are available for this session through APA AICP

Dave Courtemanch, The Nature Conservancy
Molly Payne Wynne, The Nature Conservany

Additional organizers: Karen Wilson, USM; Sam Roy, UMaine

The Penobscot River watershed, the largest and most significant watershed in the state, has been the home of the Penobscot Nation for millennia, the inspiration for Thoreau’s writings on wilderness, the industrial engine of the 20th century, and most recently, site of one of the most far reaching and innovative river restoration projects in the US.  The session will review the history of the river, effects that policy changes such the Clean Water Act and Maine River Study have had, how the region’s social and economic context have changed, and how the recent reconfiguration of the hydropower system of the river have all converged to cause a dramatic recovery. The ecosystem has been revived, water quality is the best it has been for a century, fish are returning by the millions.

Presenters are indicated in bold.

Session Presentations

  • 8:30AM – 8:55AM: The Penobscot River: From Glaciers to a Modern River, Alice R. Kelley
  • 9:00AM – 9:25AM: The Healing of a River: Changes in Penobscot River Water Quality Over the Past 25 Years, Daniel Kusnierz
  • 9:30AM – 9:55AM: Recovery of an Historic Resource: Shortnose and Atlantic Sturgeon Abundance in the Penobscot River, Catlin Ames
  • 10:00AM – 10:25AM: A data-driven approach to planning river barrier decisions in the Penobscot River, Maine, Samuel G. Roy

8:30AM – 8:55AM

The Penobscot River: From Glaciers to a Modern River

Alice R. Kelley and Roger LeB. Hooke
School of Earth and Climate Sciences and Climate Change Institute, University of Maine, Orono

This paper uses geological and archaeological research to explore the linkage between geomorphology and human settlement of the Penobscot River. Landscape analysis suggests a pre-glacial, “ancestral” Penobscot River that was reborn with the recession of the Laurentide ice sheet. Isostatic depression first created an ocean embayment across the Penobscot Lowland during glacier retreat. As the land rose isostatically, the river re-established a course, creating a watershed that included today’s drainage and that of Moosehead Lake. Glacial meltwater created a high velocity, sediment-laden river, and early cold and dry conditions promoted the formation of sand dunes. At approximately 10 ka, land level adjustment shifted the outlet of Moosehead Lake from the Penobscot watershed into the Kennebec River, decreasing the Penobscot ‘s discharge. Changing flows and sediment loads related to climatic variations alternately created terraces and exposed bedrock falls and rips. The stepped profile and generally sediment-poor nature of the Penobscot Lowland reach is a result of this history. Indigenous peoples’ use of the region was linked to the development of the river and landscape. Earliest archaeological evidence in the valley dates to the early Holocene, although the river and surrounding water-rich landscape likely provided resources and a pathway for earlier post-glacial occupants. Use of the main stem and tributaries intensified as regional drainage patterns became more established, and a varied mosaic of resources combined with integrated stream networks helped to create a culture that persists to present. The arrival of Europeans marked a changed the river through dam construction and industrialization.

9:00AM – 9:25AM

The Healing of a River: Changes in Penobscot River Water Quality Over the Past 25 Years

Daniel H. Kusnierz, Water Resource Program Manager, Dept. of Natural Resources, Penobscot Indian Nation, Indian Island, ME

The Penobscot River, home to the tribe that shares its name, has for thousands of years provided sustenance through fishing, hunting, and the gathering of plants for food and medicines. The relationship between the tribe and the river is inseparable.  Throughout the 1900s the river experienced much neglect with water quality impacts from logging, dams, untreated effluent, and industrial pollution from paper mills. This presentation will discuss the water quality improvements measured and witnessed by the Penobscot Nation’s Water Resources Program staff over the past ~25 years. Some of the improvements include reductions in point source loadings, decreases in phosphorous levels, lack of episodic algal blooms, reductions in foam and color from industrial sources, decreased levels of dioxin in fish tissues, attainment of dissolved oxygen and bacteria criteria, upgrades in water classifications, and changes to benthic aquatic insect communities. The presentation will also discuss changes that occurred after the removal of two dams in the lower Penobscot River.

9:30AM – 9:55AM

Recovery of an Historic Resource: Shortnose and Atlantic Sturgeon Abundance in the Penobscot River

Catlin Ames (student)1, Micheal Kinnison2, Joseph Zydlewski3, Gayle Zydlewski4
1 Marine Biology Program, School of Marine Sciences, University of Maine, Orono, ME
2 School of Biology and Ecology, University of Maine, Orono, ME
3 U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit and Dept. of Wildlife, Fisheries, and Conservation Biology, University of Maine, Orono, ME
4 School of Marine Sciences, University of Maine, Orono, ME

A Power Point presentation is not available for this talk. Please contact the speaker if you need additional information.

Atlantic (Acipenser oxyrhynchus) and Shortnose sturgeon (A. brevirostrum) are anadromous species listed as threatened and endangered, respectively, in the Penobscot River. Historically, these species were a significant resource of meat to the Penobscot Nation, and to European settlers in the region. Their abundance began to decline with the onset of industrialization due overharvest for caviar, and loss of habitat connectivity through dam construction. A moratorium was placed on all harvest by 1998 after the fishery collapsed. Recovery objectives included estimation of population sizes of the species but was challenging as both species make extensive movements between river systems in the Gulf of Maine. To generate biologically realistic estimates of abundance in the Penobscot River, we have combined mark-recapture methods with acoustic telemetry analysis. For the last decade, gill netting surveys resulted in the capture and unique marking of 1453 Shortnose and 224 Atlantic sturgeon with 433 and 21 recaptures, respectively. Approximately ten percent of all individuals were implanted with acoustic telemetry tags. Passive telemetry was used to estimate immigration/emigration rates, allowing the delineation of open and closed periods for robust maximum likelihood abundance estimation. Associated changes in demographic measures were also explored, including condition and growth of recaptured individuals. Population estimates suggest a stable to positive trend in population size in the River, with slow recovery likely due to late maturation and long life histories. The trend of abundances of these populations likely reflects their response to management actions such as fishery closure and dam removals.

10:00AM – 10:25AM

A data-driven approach to planning river barrier decisions in the Penobscot River, Maine

Samuel G. Roy1, Adam Daigneault2, Sean M.C. Smith3, Shaleen Jain4
1 Senator George J. Mitchell Center for Sustainability Solutions, University of Maine, Orono, ME
2 School of Forest Resources, University of Maine, Orono, ME
3 School of Earth and Climate Sciences and Senator George J. Mitchell Center for Sustainability Solutions, University of Maine, Orono, ME
4 Dept. of Civil and Environmental Engineering, University of Maine, Orono, ME


Mainers have relied on tens of thousands of culverts to connect their communities through public and private roads for over a century. As these culverts age and degrade they become more likely to fail and cause damage to roadways and property. Many older culverts are now undersized for increasingly larger floods and bank erosion caused by climate and land use changes. Maine is also home to many aging dams that have long outlived their original purposes and now pose similar failure risks. Many of these underperforming river barriers prevent sea-run fish from reaching spawning and rearing habitat, cascading negative impacts into freshwater and marine ecosystems in ways that also diminish cultural, sustenance, and economic values in local communities.

We test a multi-objective machine learning approach to identify river barrier decisions that may lead to improvements in river ecosystem connectivity and infrastructure safety in the Penobscot River basin. A third objective is used to minimize the cost of culvert replacement and dam removal/modification because these decisions are expensive and challenging to exact within limited budgets of practitioners. Using our approach, we explore several coordinated decisions that may provide significant improvements in ecological connectivity and infrastructure safety at different budgetary levels. We find the number of barriers included in the assessment influences potential improvements and budget sizes, with larger-scale decisions providing overall greater improvements at lower cost. Finally, we explore the logistical challenges of coordinating these decisions, including needs for broad stakeholder engagement, restoration interests, local regulatory requirements, and private ownership.