WEST LEBANON — A 6-acre parcel of developer David Clem’s River Park subdivision would be preserved in perpetuity as open space under plans unveiled last month, giving West Lebanon a long-sought-after riverside park.

Clem hopes to donate the riverfront property he purchased in 2007 as part of plans to build 840,000 square feet of life science, office, retail and residential space on the 38-acre River Park parcel between Route 10 and the Connecticut River.

Friends of River Park, a New Hampshire nonprofit Clem formed in 2015, would be charged with overseeing and upgrading the property to potentially house trails, a boat launch and other amenities. The Upper Valley Land Trust also would hold a stewardship easement, the developer said in a Nov. 15 post on his blog.

“We think this is an enormous opportunity to sort of ‘fix the smile’ of river frontage” in West Lebanon, Clem told Lebanon’s Conservation Commission during its meeting a day earlier.

Clem — who has helped build life science projects in Houston; Cambridge, Mass.; and Boston’s Longwood Medical Area — also hopes to double the contribution his company, Lyme Properties, will make to the city when taking River Park land out of the state’s current use program, which provides tax breaks for agriculture and forest land.

Developing the land would require Lyme Properties to take it out of current use and force Clem to pay a penalty, which will go into a Lebanon-run conservation fund. He’s offering to double that amount if the city promises to direct it to Friends of River Park to help with the riverside park.

West Lebanon has long sought a riverfront park.

Chet Clem, president of Lyme Properties and David Clem’s son, said that plans to set aside open space at River Park date back to 2008, when the company began surveying the neighborhood on its hopes for future development. At the time, residents not only clamored for a park but also connections to trails and surrounding recreational opportunities, Chet Clem said.

In the years since, Lyme Properties has solicited designs of a future park and sought ways to connect River Park to the north, where trails could link up with the city’s Boston Lot conservation area. To the south, the company also has attempted to extend access to potential parks planned for downtown West Lebanon and the old Westboro Rail Yard.

“My hope is we can get a pretty unique model that will accomplish much of what people have been talking about for years: public river access, connectivity,” Chet Clem said.

However, longtime Conservation Commission member Susan Almy worried the park could be overdeveloped, saying a gazebo, ball fields or other forms of recreation could be “too urban.”

“It should really just be a trail along the river. That’s what we want,” she said Thursday.

Almy said she hopes the Conservation Commission will have a say in the park’s future, adding the city has to be careful changing land so close to the river.

“I think that in general people believe that it’s a good thing to have but not as a built up kind of thing,” she said of the park. “Nothing along there is built up now.”

In the meantime, Lyme Properties has kept the lot open to the public. People can be found walking dogs and fishing in the summer, while the occasional snowshoer can be seen making their way through the open fields in winter.

“We’ve been mowing the fields and creating trails and allowing our neighbors access,” David Clem told the Conservation Commission in an audio recording of its Nov. 14 meeting.

Lebanon Planner Mark Goodwin commended the Clems on their plan to donate the parcel Wednesday, saying the public has expressed “considerable interest” in being able to access the riverfront.

Lyme Properties’ proposal to double its financial contribution and make way for improvements goes “above and beyond” what the city requires, Goodwin added.

However, the city officials cautioned that finer details still need to be worked out.

Chet Clem acknowledged there’s more work to be done. The land donation likely will come next year, around the same time Lyme Properties starts construction of 100 River Park, the development’s first structure.

The 64,000-square-foot space is expected to house laboratories, offices and retail and cafe space. Construction is scheduled to start in April, Chet Clem said.

In the meantime, Friends of River Park could reform and restart operations.

The group’s 2015 articles of agreement show Kathleen Shelton Clem, David Clem’s wife, listed as its president.

Chet Clem and Angela McCanna, Lyme Properties’ executive assistant, are also board members, according to documents filed with the New Hampshire Secretary of State.

That board was meant to be a temporary placeholder, said Chet Clem, who wasn’t working with his father’s company when he signed on.

“We’re working on that file from 2015 to determine how to best balance the board,” he said.

Tim Camerato can be reached at tcamerato@vnews.com or 603-727-3223.