It took a lot of work to get to this point, but Oak Harbor leaders have finally narrowed the prospective sites for the new wastewater treatment plant to just two.

Members of the city council adopted a resolution last week that identifies Windjammer Park and “Crescent Harbor North” as the sites which will be further evaluated by the engineering firm hired by the city. The decision comes after more than two years and four public meetings, six city council workshops, nine formal city council meetings and dozens of committee meetings at which the issue was discussed.

City Engineer Eric Johnston said the plan is to have the analysis completed in time for the city council to pick the preferred site by mid-August. Engineers need time to submit a facilities plan, based on the final site, to state regulators by the end of the year.

“We’ve been looking at this from the 5,000-foot level,” he said. “We need to get down to the 2,000-foot level and narrow down the details.”

Judging from discussions at the council meeting, it isn’t going to be an easy decision. The council members have to consider the price tag that could reach as high as $95 million, the impact on monthly sewer rates, the type of technology to use, the possibility of phasing in the project, the effect on neighbors and the future of the city’s popular waterfront park, long the butt of smelly jokes over the existing sewer plant.

Carollo, a California-based engineering firm, used a “triple bottom line plus” analysis to judge six potential sites in and around the city. The engineers scored the different sites on a wide variety of factors, including cost, ease of construction, public health, the impact on neighbors and water quality.

The Crescent Harbor North site earned the most points under the analysis. It consists of a 24-acre site on private property on the north side of Crescent Harbor near Torpedo Road. The area is just outside city limits and includes nine properties under four ownerships. Two of the property owners indicated they may be interested in selling. The estimate for a membrane bioreactor plant — the cleanest type of system being considered — at the site is about $95 million.

Besides the cost, the other main disadvantage of the site is the impact on residents. There are the property owners who may be forced to sell their homes and neighbors who don’t want to live next to a sewer treatment plant, even if it is virtually odor free.

“There are people who live there and the city is very, very sensitive to their personal property concerns,” Johnston said in an interview.

Several of the people who live in the Crescent Harbor area spoke in opposition to the site, expressing concerns about groundwater and wetlands. Others were concerned about the cost.

“We have a responsibility to the public to keep the costs down and the only way we’re going to do that, honestly, is with Windjammer Park,” Ferron Rice said.

The Windjammer site, the location of the current plant, is the second choice. The main advantage is the cost savings because of its location. All sewage in the city runs to the pump station at Windjammer, meaning the city won’t have to install a costly conveyance system and lift stations to pump all the sewage to the other side of town. The preliminary cost estimate for a membrane bioreactor plant at Windjammer is $90 million.

Yet Johnston said the Windjammer site offers the city the greatest opportunity to phase in the project, which is also the best way to control sewer rates. Under this approach, the city could build the first phase and get it up and running at Windjammer for less than $70 million by the 2017 target date.

The disadvantage of Windjammer is also the location. Many residents don’t want the new facility built in the middle of the waterfront park.

“We do not want to lose one inch of that park for a sewer treatment plan,” said Dee Harbour, a member of the city’s park board.

Resident Mel Vance said the public is opposed to a sewer plant in the park.

“The only universal answer that you will receive is, ‘Don’t put it in the park,’” he said, suggesting that council members ask residents where they want the plant sited.

Yet Johnston stressed that the Windjammer “site” to be evaluated includes other property, including commercial land, in the vicinity of the city’s popular waterfront park. Conceivably, the facility could be built only partially in the park, or outside the park completely.

Johnston told the council that engineers will be looking at other options that could impact costs, including the possibility of building an activated sludge system at the Crescent Harbor site. The system takes more space than a membrane bioreactor and requires multiple processes to produce water that’s almost as clean as a membrane bioreactor plant, but it would save money.

The public will have further opportunities to weigh in. Information is available at www.oakharborcleanwater.org.