Construction of a 22-story luxury condominium tower at 150 Seaport Boulevard will begin this spring after South Boston developer Cronin Group agreed to pay $18.5 million toward a future waterfront park and enrichment activities on Boston Harbor for underprivileged youths.

Boston-based Conservation Law Foundation, which had argued that such projects threaten to turn the Boston waterfront into “the sole playground of the rich,” agreed to drop a Suffolk Superior Court lawsuit challenging approval of the 263,000-square-foot tower on the site of the Whiskey Priest bar and former Atlantic Beer Garden.

“This is a great victory for public access to the waterfront, and the benefits in this package exceed anything we could have gotten in the litigation process,” CLF President Brad Campbell said.

CLF argued in a lawsuit filed last February that the project violated longstanding state law that preserves public access to privately owned properties on tidelands.

Chapter 91 regulations limit the height and density of non-maritime commerce waterfront developments and typically require that new buildings provide facilities of public accommodation such as visitor centers or observatories.

Cronin Group argued that the project would increase public access by extending the Boston Harborwalk to the neighboring Commonwealth Pier property and adding a 10-foot-wide walkway wrapping around the back of the tower, along with a restaurant on the first and second floors. The developer also agreed to off-site mitigation, including a $1.5 million donation toward construction of Martin’s Park on Fort Point Channel.

In the settlement reached this week, Cronin Group agreed to build a public dock similar to one included in developer Tishman Speyer’s nearby Pier 4 office and condo project, pay $13.1 million over 35 years for a new waterfront park and contribute $5.4 million over 65 years to support programs on Boston Harbor for underprivileged children, Campbell said.

Negotiations on a settlement intensified after CLF recently filed an administrative appeal of the DEP-issued waterways license, he said. CLF has filed dismissals of both the court case and the DEP appeal.

Location of the public park is yet to be determined but potential sites include the dormant Drydock No. 4, and the Pier 7/Wharf 8 site between Liberty Wharf and the Blue Hills Bank Pavilion, Campbell said.