Plans for the restoration of Fort Gorges in Casco Bay received a boost Monday after the city of Portland announced a public-private partnership between the city, preservationists and the U.S. Army Corps of Engineers.

Beginning next spring, the Army Corps will initiate hazard mitigation at Fort Gorges in hopes of restoring it as a historic site.

In addition, the city of Portland has secured a $20,000 grant from the Maine Historic Preservation Commission to help pay for a master plan that will identify possible future uses.

The city announced the partnership Monday between Portland, the Army Corps and Friends of Fort Gorges, a nonprofit group that re-formed last year with a goal of resurrecting the former Civil War-era site.

“I’m really pleased to see that we have this public-private partnership that is committed to preserving Fort Gorges,” City Manager Jon Jennings said in a statement. “This joint effort is really important given the financial undertaking that is involved. The fort is certainly an untapped treasure in Casco Bay, and I look forward to beginning the public process.”

Located on an island in Casco Bay off Portland, Fort Gorges was built during the Civil War but was never garrisoned. It was modeled after Fort Sumter in Charleston, South Carolina.

Nearly 100 years after it was built, the U.S. government gave the fort to the city of Portland.

Marked by its six walls of granite topped by a layer of grass, Fort Gorges is open to the public but its access is limited because the only way to get there is by private boat. Thousands pass the fort daily during trips to one of the many islands in Casco Bay and it can also be seen from many spots on the mainland in Portland, South Portland and Cape Elizabeth.

The fort is named for Sir Ferdinando Gorges, who in the early 1600s was credited with discovering the land that is now Maine. The fort was commissioned after the War of 1812 but wasn’t completed until just after the Civil War ended.

Ironically, the fort was largely obsolete by then. There were plans to modernize it, but that never happened. It was last used during World War II for storage.

Because it was never maintained regularly, the granite structure is badly in need of maintenance.

Paul Drinan, executive director of the friends group, said last year that Fort Gorges is a local treasure that should be saved. The group was founded in 2000 but had been dormant for many years.

“Thousands of people appreciate the fort every year, either in person or from afar, and this is our first, and perhaps last, best chance to preserve this unique historical gem for future generations,” he said. “Aside from preserving this asset to our community, the economic, cultural, educational and historical opportunities the fort provides are numerous.

“If we don’t act now, Fort Gorges could become Portland’s next Union Station – once admired and appreciated, then lost.”

In a statement Monday, Drinan said the friends group was pleased to have the city as a partner. The $20,000 grant from the historic commission will certainly help but the friends group also has been fundraising. Drinan had estimated that the planning study alone could cost up to $180,000. Renovations, he said, likely would cost millions.

The Army Corps’ work will mitigate some cost. The hazard mitigation project was identified and approved in the mid-1990s under the Army Corps’ Defense Environmental Restoration Program, but funds were never dedicated until recently.

The city and friends group hope to form a planning committee in the next several weeks and then host a public forum later in the spring.

Portland’s Historic Preservation Board will hold a workshop at 5 p.m. Wednesday to review the Army Corps’ preliminary plans and specifications for safety improvements.