Penobscot River Processes and Management

UMaine Alert

Posted: April 19, 2024 - 1:32 PM

At approximately 9:24 a.m. on Friday, April 19, a University of Maine graduate student was struck by a university vehicle on Long Road at the University of Maine campus in Orono. The student reports that they are at a local hospital with minor injuries.

Emergency services, including the Orono Fire Department, University Volunteer Ambulance Corps, University of Maine Police Department, Orono Police Department and Penobscot County Sheriff’s Office responded to the scene.

The university vehicle involved in the incident was a Chevrolet Express van. It was being operated by a university employee.

Counseling services and support are available for students, faculty or staff who may have been affected. The Counseling Center can be reached at 207-581-1392 and the Dean of Students Office can be reached at 207-581-1406.

The scene has been cleared and Long Road is now accessible. An investigation is being conducted by the University of Maine Police Department with assistance from the Penobscot County Sheriff’s Office Crash Reconstruction Unit. Any witnesses to the incident are encouraged to contact Lt. Noel Santiago at noel.santiago@maine.edu.

The Penobscot River is the mightiest of Maine’s coastal rivers, with a watershed covering ~8,600 square miles (22,274 square kilometers) of land across seven Maine counties and stretching from its mouth near Bucksport in Penobscot Bay to the drainage divide in the Boundary Ranges of the Appalachian Mountains at the state’s western border with Quebec. The Penobscot watershed is the homeland of the Penobscot Nation and the river is integral to cultural and traditional practices.

Over the past two centuries, the construction of large channel-spanning hydropower dams has changed the water flow regime in the river, prevented navigation, and closed thousands of miles of habitat for sea-run (diadromous) fish. In recent years this trend of dam construction was reversed with multiple dams being removed to return the lower Penobscot to free-flowing conditions.

WPES members have been involved in research surrounding the ways the river has responded to the changes related to land uses, dam construction and maintenance, and climate.

Penobscot Geomorphology

Landscape Scale

Aerial view of the Penobscot River watershed. — *Penobscot River watershed shaded relief map showing varied elevations from tectonics, glacial retreat and advance, and erosion.*

Long-term geological processes create structures that have a substantial influence on the modern form, position, and profile of the river system. The geologic materials also are the parent material for soils in the watershed and that supply sediment of varied grain sizes to the river.

Regional Geology – Geologic history of the Penobscot River basin.

Watershed Scale

Penobscot River watershed with roads and dams. — *Shaded relief map of the Penobscot River watershed showing roads, dams, and the channel drainage network.*

The dimensions of the Penobscot River watershed are predominantly governed by landscape-scale processes related to long-term tectonics, geology, and glaciation in the region. Humans have also influenced the modern dimensions of the watershed through flow diversions at the upper most ends of the basin.

Reach Scale

Plan view of the Penobscot River at Ayers Island in Orono, showing locations of valley cross sections used in a hydraulic model.

Surface water from precipitation and groundwater flows moving through the Penobscot River watershed travels from hillslopes into streams a person can jump over to large rivers you need a boat to cross. The streams and rivers comprise the watershed drainage network made up of links having unique characteristics governed by the geology, climate, watershed characteristics and position, and disturbances from human activities. Segments within the river mainstem and tributary streams are referred to as “reaches”, which can have unique characteristics relative to upstream and downstream locations in a drainage network.

Feature Scale

Man made features called “boom islands” from historic log drives on the Penobscot River. Learn more about how remnant boom islands can influence modern flow dynamics here.

Each reach of the Penobscot River drainage network is characterized by a collection of features related to structures, channel form, bottom substrates, and hydraulic conditions. The features influence flow dynamics, ecological conditions, and aquatic habitat important to many fish species.