Construction will begin on the $5.3 million, two-story Onset Bay Center within a few weeks, Buzzards Bay Coalition officials have announced.

The center will serve as headquarters for on-the-water programming for thousands of people each year and replace the 19th century-built bathhouse.

Mark Rasmussen, president of the New Bedford-based nonprofit, said designs are complete and a groundbreaking ceremony will be announced soon. He expected the new center would be finished by summer 2019. However, the construction schedule depends on winter weather.

“We’re hoping to be ready for next season, but there’s always a chance a bad winter could slow down the work,” said Rasmussen. “Whether or not the center is done, we will have several programs ready for people to take advantage of.”

Over the past two years, coalition officials have tested the waters, so to speak, with sailing and boating lessons as well as nature programs on Wickets Island and Burgess Point.

Rasmussen said the coalition was looking forward to offering year-round programs from the Onset Bathhouse headquarter.

Designs call for constructing the center in the footprint of the current building and adding a second story. Rasmussen said the view of the bay from Waterfront Park, on the bluffs, will not be obstructed.

The new building will retain some aspects of the historic bathhouse, which was originally two stories before it burned down in the 1800s.

Rasmussen noted that the first floor of the new building will be dedicated to storage mostly, with some office space set aside for town use. Nemasket Kayak, which operates out of the bathhouse in the summer, will also remain.

The second floor will include classroom and gathering  space for programs, meetings and administration.

As the centerpiece of the coalition’s efforts to open Onset Bay up for a variety of people, the bathhouse is part of an effort to restore Wickets Islands to improve safety, public access and natural habitats. The coalition also owns land and docks on the nearby Burgess Point.

Wickets Island improvements include removing invasive plants, building a new steel staircase, trail and picnic area on the island and adding a new floating dock for boaters.

Some site work on Wickets Island is starting this month, Rasmussen said, adding residents shouldn’t be surprised to see a crane on the island.