The occasional stench wafting over homes abutting the town’s Water Pollution Control Facility has always been irritating for residents. But for the past two years, neighbors say the odors have become increasingly strong, unpredictable and a potential health hazard.

“It’s almost like being in an abusive relationship,” said Sally Morrison, of Linwood Avenue. “You never know when you’re going to get hit next.”

Thirty-eight neighbors say the smell has become intolerable and have made the State Department of Environmental Protection aware of the issue. On Aug. 5, those residents outlined their complaints in a letter sent to the DEP, the Board of Health, Selectmen, the Sewer Commissioners and Water Pollution Control Director Guy Campinha.

Morrison said the letter followed years of complaints about the smell, which comes and goes at random times, but is more frequent in the summer.

According to the neighbors, the stench is so overpowering that it’s cancelled outdoor events, woken people up at 2 a.m. and caused headaches.

Morrison said prior to sending the letter, neighbors approached the Sewer Commissioners and Campinha with their concerns, but were unsatisfied with the response. The hope, she said, is to get the DEP involved to find a solution.

Campinha said he’s heard the neighbors’ complaints and has introduced a number of measures to mitigate the smell.

There’s only so much to be done, however, because of the rapid expansion of homes that have been tied into town sewer.

“Unfortunately, what has also happened over the years is that Wareham wastewater has grown at a very fast rate,” said Campinha. “The original plant design cannot meet the wastewater discharge permit requirements without temporary storage to normalize the peaks.”

By temporary storage, Campinha is referring to a large, open air basin on the facility that stores overflow sewage when the plant is at capacity before treatment.

When the basin fills up, generally the odor complaints follow.

Campinha said he’s sympathetic to the neighbors, but unless the plant is expanded to handle the additional flow, there’s only so much to be done.

“In the interim we are exploring chemical addition, temporary covers, counteractants, fencing to redirect air flow, air scrubbing pods, and other measures to limit odors,” he said. “Odor control is on my mind every day.”

Aside from the smell, the neighbors raised concerns about air quality.

“It makes you wonder what you’re breathing in when the smell is masked with the perfume they use,” said Richard Parsons of Santos Drive, referring to an odor masking agent sprayed near the basin. “You’re just replacing one stink for another.”