BANGOR – Nearly two decades after it became the focus of a redevelopment initiative, the city’s once rough-and-tumble waterfront is well on its way to becoming a destination for residents and visitors in search of entertainment, access to the Penobscot River and outdoor recreation.

With various infrastructure improvements under way, city officials are putting out a call for private investors to set up shop.

An updated master plan for “Bangor Riverpark on the Penobscot,” as the city’s waterfront is now called, will be presented from 10 to 11:30 a.m. today in the council chambers at City Hall.

Presenters will include city leaders and Pam Shadley, a principal of Boston-based Carol R. Johnson Associates Inc., the landscape architectural firm that developed the plan.

Potential developers, those who may be interested in opening a business on the waterfront and members of the public are encouraged to attend.

The effort to revive the city’s once industrial waterfront began in the mid-1980s, when the city began acquiring industrial sites near the Joshua Chamberlain Bridge.

Business owners and developers in the area joined in, renovating several properties near the city docks. Many in the city credit Community and Economic Development Director Rod McKay, who has been involved in the effort from the beginning, for the vision that’s evolving for the 1.5-mile-long strip along the Penobscot.

To date, the city has acquired, cleared and prepared for development and reuse 32 acres of prime waterfront property. It has invested more than $5 million in site work and infrastructure improvements and received approval for more than $15 million in federal and state grants, loans and appropriations to support private development.

In addition, Bangor businessman and community leader Chris Hutchins has pledged $3 million to build an amphitheater on the site.

Construction has started on new utilities, streets, walkways, parking, landscaping and other public improvements. The work began last fall on Front Street. The focus this year will be on Railroad Street, which is at roughly the center of the recently established long Waterfront Development District. Railroad Street will serve as the main gateway to Bangor Riverpark.

The landscape firm’s master plan is based on a previous version prepared in 1999 by Hunter Interests Inc. of Annapolis, Md., according to Shadley. Where the Hunter plan was more of a feasibility study, the current plan addresses specifics.

“We kept the best pieces of it and revised the pieces that we’ve learned more about,” Shadley said Wednesday.

Some of the changes resulted from a traffic study that looked at movement between Main Street and the Chamberlain Bridge. To improve traffic flow, city officials are thinking about discontinuing the section of Summer Street closest to Railroad Street and opening that land to development.

Last year’s National Folk Festival also prompted some changes.

“I think the success of the folk festival has [resulted in] a new focus on the waterfront,” Shadley said.

To that end, the landscape plan calls for a greater ratio of open space to developed space. City officials also are working with Hutchins on placing the amphitheater on an undeveloped parcel along Railroad Street, between Main Street and the Penobscot River. (For those who attended last year’s folk festival, the site housed the Railroad Stage and the 90-foot-tall pole used by the Papantla Flyers.)

Some key features of the master plan are that it will result in significant landscape and streetscape improvement that will better connect the waterfront and the downtown.

“This plan concentrates more on the waterfront connecting to the downtown and making this an easy walk to make – it’s a walk that we want people to make,” Shadley said. “We concentrated on attractive, wide and safe sidewalks that are well lit and well signed.”

The plan divides the waterfront area into 11 project areas, the first three of which are fully funded, Shadley said. The funded areas are Front Street, Railroad Street and the water’s edge.

The city is seeking proposals from prospective developers interested in building:

. A headquarters hotel – The city envisions a multistory hotel, with a lobby, restaurants and a bar, reception areas, administration and more. The proposed hotel would feature four upper floors and up to 250 rooms, with high-quality furnishings and equipment.

. Office buildings – The city is seeking developers for one or more quality buildings designed for office or mixed use.

. Retail-restaurant pavilions – Two two-story structures are sought to house specialty retail shops and multiple restaurant and entertainment venues featuring river views. These facilities also could house the harbor master’s office, a visitor center, retail, food and beverage vendors, historical components and the intermodal transportation options for which $1.5 million has been provided by the U.S. Department of Transportation.

. Retail-restaurant pavilion – The master plan calls for a one- or two-story structure that could accommodate one or more restaurants.

. Residential units – Up to 100 upscale two- and three-bedroom luxury apartment or condominium units are wanted.

The deadline for proposals is May 21.

The city’s efforts to breathe new life into the once neglected waterfront have started to pay off.

Last summer, it was the venue for the National Folk Festival, which drew more than 80,000 people over three days last August. This August, Bangor will host the 65th edition of the National Folk Festival, the second year in its three-year run here.

Last fall, Connecticut-based American Cruise Lines added the Bangor waterfront to its roster of homeports for this year, next year and possibly beyond that. The 165-foot cruise ship American Eagle will board passengers at Bangor for seven consecutive trips the next two summers, a move city officials project could pump between $500,000 and $750,000 a year into the local economy.

Last week, the Sea Dog Brewing Co. reopened under new ownership after having been closed for several months. The brew pub, which occupies a historic former warehouse, is an important anchor for the waterfront in that it is a year-round “people generator,” McKay said.