WESTBROOK — As the Friends of the Presumpscot River celebrate the organization’s 25th anniversary, it’s seeking to acknowledge the river’s past and preserve it for the future.

The organization hopes to designate a portion of the river as a historic and natural river corridor. The designation is purely symbolic, but will be used to market the river and draw more people to enjoy and use it.

“It’s time to make a statement that this is a valuable asset,” said Michael Shaughnessy, the president of the board of Friends of the Presumpscot River. “This natural river way is an asset not only to those right near it, but to the greater community.”

The Westbrook City Council and Windham Town Council have approved this designation and the Gorham Town Council is expected to do so on Tuesday night. Once fully approved, Shaughnessy said the Friends can use the designation to market the accessibility and recreational possibilities of the river.

“It’s a wonderful connector and I hope it can bring the communities together,” he said.

Shaughnessy said he also hopes the designation will prevent people from wanting to develop properties and businesses along the largely undeveloped river corridor.

“Hopefully people won’t want to develop it because they’ll realize it’s more valuable to be next to it instead of on it,” he said.

Jennifer Cook, a communications consultant for the group, said the Friends wants to do more to engage the public with the river by hosting lectures about it and giving guided river floats.

“Presumpscot has come up again and again as an asset for the city,” she said.

Part of this public engagement includes a 25th anniversary celebration on Sept. 28. The event, which will take place at Fresh Water Farm at 89 Conant St., will include a memorial event and a dinner.

The memorial event will commemorate Chief Polin, the leader of the Wabanaki tribe who in the 1700s led the first known dam protest in New England. Cook said it’s important to remember the impact Chief Polin had in the Westbrook area.

“There’s nothing to commemorate the indigenous people in the area,” she said.

Shaughnessy said it’s important to “acknowledge this culture that was here for so many years.” Large stones have been laid at the site of the memorial and the Friends of the Presumpscot will soon start a fundraising campaign to purchase plaques to set into the stones. The plaques will detail the history of the river and Chief Polin.

Cook said the Friends expects to install the plaques in the spring and hold another ceremony at that time. She said this week’s ceremony is to increase awareness of the campaign and of the river’s long history.

“It’s to build excitement and awareness that this is happening,” Cook said.

The memorial will begin at 5:30 p.m. on Thursday and the dinner will take place on site at 6:30 p.m. The suggested donation for the event is $50 per person.

Kate Gardner can be reached at 781-3661 ext. 125 or [email protected]. Follow her on Twitter: @katevgardner.

The Friends of the Presumpscot River on Sept. 28 will celebrate the river’s history by unveiling stones, which will have plaques installed on them in the spring, to commemorate Chief Polin, who protested dams in the 1700s.