GARDINER — Upstream activist Steve Brooke will present “Cobbosseecontee: On the Edge of Restoration” from 6 to 7:30 p.m. Tuesday, April 23, at Gardiner Public Library at 152 Water St.

Those who attend can learn the history of the waterway and what is happening today to secure fish passage for its watershed, according to a news release from Tina Wood of Upstream.

Dammed at its head of tide in 1761, Cobboseecontee Stream is the largest coastal watershed in Maine (after Presumpscot River/Sebago Lake) still impassible to native migratory fish. A tributary of the Kennebec River and upper Merrymeeting Bay, the Cobboseecontee watershed includes the communities of Gardiner, West Gardiner, Litchfield, Richmond, Winthrop, Manchester, Monmouth, Readfield and Hallowell. It contains 20.3 square miles of lakes and ponds, the largest being Cobboseecontee, Maranacook and Annabessacook, according to the release.

Working from 1998 to 2004, a consortium of local citizens, citizen conservation groups and state and federal agencies secured $125,000 in funding for the necessary engineering studies, legal permits and construction contracts to breach and remove the first dam in the watershed, the 180-year-old Gardiner Paperboard dam in downtown Gardiner, according to the release.

After the hired contractor failed to perform the dam removal in autumn 2004, the dam and adjoining property were subsequently sold to several entities, the most recent of which has declined interest in re-initiating the dam removal project. Options available for securing native fish passage include public/private efforts by willing dam owners to provide fish passage, invocation of the State of Maine’s fishway law and use of the Endangered Species Act for endangered Atlantic salmon native to the watershed, according to the release.

Brooke served as project coordinator of the Kennebec Coalition during the decommissioning and removal of the Edwards Dam in Augusta on Maine’s Kennebec River. After retiring from the State Planning Office, he works with Upstream, a Gardiner nonprofit working to return river herring to the Cobbossee watershed.

For more information, contact Wood at 582-0213 or  upstreamcobbossee@gmail.com or visit the Alwives Upstream Cobbosseecontee facebook page or sites.google.com/view/upstreamcobbossee.