Environmental advocates say the completion of a fish bypass around a dam in Howland is the final major milestone in a project designed to restore the Penobscot River.

Howland Bypass /J.Royte TNC Lighthawk/NRCM

The river, popularized in print and film by Henry David Thoreau, Stephen King and Tom Clancy, gave rise to dozens of towns and cities in central and northern Maine and has been important to native peoples for tens of thousands of years.

Howland Dam Bypass/Natural Resources Council of Maine

The Natural Resources Council of Maine says the bypass is a channel that resembles a stream. It will allow shad, herring and salmon to swim around the dam to historic breeding and nursery habitats.

The fish bypass at the Howland Dam /Natural Resources Council of Maine

The group says the bypass will reopen those areas for the first time in more than 100 years. The work is part of the Penobscot River Restoration Project, which seeks to improve access to almost all of the river.

President of the Penobscot River Restoration Trust board Don Hudson presents Laura Rose Day, executive director of the Penobscot River Restoration Trust, with a Visionary Award

The Penobscot, at 109 miles long (175 km) is the largest river in Maine, with the West and East Branches extending the overall length to 264 miles (425 km). Its drainage basin contains 8,610 square miles (22,300 km).

The channel is 1050 feet long and about 200 feet wide . The width at the bottom of the channel is 105 feet.

Karen Talbot painted this beautiful artwork in celebration of the Penobscot River Restoration Project /NRCM Facebook

The Howland natural bypass channel design is one of the largest and most complex ever constructed on the east coast.

Natural Resources Council of Maine/Facebook

In June 2004, seven conservation groups, the Penobscot Indian Nation, state and federal resource agencies, and dam owners signed the Penobscot Agreement. On June 16, 2010, the Federal Energy Regulatory Commission approved the Penobscot River Restoration Trust's applications for changes to three hydroelectric power projects in the lower Penobscot River drainage, including Howland Dam.

Howland Fish Bypass construction/Howlandmaine.com

The trust worked to remove the two lower-most dams, Great Works in 2012 and Veazie in 2013, construct the fish bypass around Howland, and improve fish passage on several of the remaining dams.