Selectmen on Tuesday reversed part of an earlier decision, relieving the owner of an unbuildable lot at 2 Preservation Way from paying a $18,000 “betterment fee” for sewer installation.

But their August decision stands that the owners of three neighboring lots in the group of homes off of Cromesett Road, all three with houses, will have to pay the fee – despite their having been assured in writing by the then-head of the sewer department that their properties were not part of the controversial sewer project.

Selectmen rejected a request for an abatement -- essentially, a forgiveness of the fee -- in the amount of $18,000 for 2 Preservation Lane, along with three other properties in a development off of Cromesett Road, at their August 20 meeting.

But since the 2 Preservation Way lot is unbuildable, it is not required to connect to sewer.

"We made an error," said Selectman Alan Slavin. "We lumped that [property] in with the others we denied."

Selectmen determined at the August 20 meeting that the other three property owners would have to pay the betterment fees and connect to town sewer.

The property owners took issue with being assessed betterment fees, and pointed to a 2009 letter sent to the developer of the properties, Scott Blagden, by then former Water Pollution Control Facility Superintendent David Simmons which states: "There will be a sewer stub installed at the intersection of Cromesett Road ... but the existing homes in these neighborhoods will not be receiving a sewer stub for their individual property and therefore will not be assessed a sewer betterment and/or be required to connect to town sewer."

The Selectmen, who also serve as Sewer Commissioners, are the only ones with the authority to determine whether or not a does or does not need to connect to town sewer.

Wareham began expanding the sewer system to more neighborhoods over the last decade in to reduce pollution in local waterways. When the town expands the sewer system, each homeowner in the newly-sewered area is charged a "betterment fee" that pays for the cost of the project.

While betterment fees are traditionally set by dividing the total cost of a project by the total number of properties in the neighborhoods in the contract, residents of the Oakdale and Cromesett neighborhoods successfully petitioned Town Meeting to cap their betterment fees at $18,000, after arguing that the betterment assessment process was flawed. The residents of Oakdale and Cromesett would have paid $21,339.

On Tuesday, the board also agreed not to bill three other properties for sewer user fees, for a total of $1,874.92, because the water had been shut off or the property had been demolished.