The Department of Inland Fisheries and Wildlife has ruled that the Sappi mill in Westbrook must construct and maintain a fish passage at the Cumberland Mills Dam on the Presumpscot River, according to a press release from the Conservation Law Foundation.

In the release, the foundation called the ruling a “major step” toward bringing migrating fish back to the river and the first decision in more than a century under a state statute that requires dam owners to maintain fish passages.

“We’re ecstatic about this,” said Douglas Watts, executive officer of Friends of Sebago Lake. “This is something we’ve been working on for 10 years.”

Watts said the ruling isn’t only good news for the health of the river, but for the eventual restoration of Sebago Lake, as well.

The ruling was the result of a proceeding initiated by Friends of the Presumpscot and American Rivers in 2006 after the U.S. Supreme Court upheld conditions in federal licenses that require the mill to maintain fish passages at its other dams. The Cumberland Mills dam is not regulated by a federal license, however, because it does not produce power. Therefore, the Supreme Court decision did not apply to that dam.

“Prior to the Industrial Revolution, the Presumpscot was teeming with Atlantic salmon, shad and river herring,” said Sean Mahoney, director of the Conservation Law Foundation’s Maine Advocacy Center. “But for more than a century, we literally turned our backs to the Presumpscot River, dumping all manner of industrial waste into it and in the process making it known more for its stench and ability to peel paint than for anything else. Since passage of the Clean Water Act almost 40 years ago, we have made great strides in restoring the water quality of the Presumpscot and other rivers around the state. This decision brings us one step further in that process.”