Stonington — A group of Masons Island residents have lobbied accusations that St. Edmund’s Retreat on Enders Island has completed work without the required permits and now accuses the town of giving the center preferential treatment.

In an August 24 letter to the Planning and Zoning Commission, 24 residents of Mason Island said that the retreat center on Enders Island has ignored town zoning regulations for years without penalty and asked the commission to ensure the center complies with all local zoning regulations.

“Equal and unbiased treatment of all property owners is the cornerstone of effective zoning,” it states.

The island is the site of a Catholic retreat center, offering numerous religious-based programs including marriage retreats, pastoral counseling and bereavement and addiction recovery retreats. Additionally, the center houses a residential addiction recovery program.

In 1954, when Alys Enders donated Enders Island to the Society of St. Edmund Inc. by quit claim deed, there was no zoning. When zoning was established in 1961 and then amended in 1977, religious use of the now residentially zoned island became a legal non-conforming use. State law typically prohibits expansion of a legal non-conforming use.

In the letter, the residents acknowledges that some of the current uses of the property are pre-existing and non-conforming, but those uses cannot be expanded, which it claims the center has done repeatedly over the last 25 years. Neighbors have also complained that the retreat center hosts events such as “Holy Smoke,” an annual cigar dinner with “fine wine and spirits,” an auction and live music.

The letter documents several occasions since 1998 when it claims expansions were made without necessary permits, and, though the town noted them in compliance reports and documents, no action was taken.

“Decisions about uses of the property still require oversight by Town officials. Regardless, various expansions have taken place,” the letter reads.

The complaint alleges a parking lot was constructed this year without a permit and a gazebo, demolished as part of extensive work to a patio next to Enders House, was reconstructed without approval.

“These apparent violations of local zoning regulations undermine the objectives of good planning in the Town of Stonington and are detrimental to the surrounding residential neighborhood,” it said, and requested the center be required remove the lot and return the area to its original state.

Town planning department documents from August 22 state that the retreat center will remove the gazebo, but that the alleged parking lot is a gravel pad the center installed ahead of an upcoming site plan application.

Town Planner Clifton Iler said last week that the center has agreed to rope off the area to prevent parking but will not remove it.

Deb Newman, St. Edmund’s Retreat vice president of advancement, confirmed Tuesday that the gravel pad is related to a planned upgrade to septic systems on the island, some of which are more than 100 years old.

The town has applied for a $600,000 Small Cities Community Development Block Grant, funded by the United States Department of Housing and Urban Development through the Connecticut Department of Housing, which will cover approximately half of the $1.25 million-dollar upgrade.