Waterford — A national group of experts in American landscape and architectural history, historic preservation, real estate development and hospital architecture are urging state officials to choose a future for the former Seaside tuberculosis sanatorium that keeps historic buildings there standing.

Two of the buildings at Seaside were designed by Cass Gilbert, the architect of the U.S. Supreme Court building and other national landmarks, and the property is listed on the National Register of Historic Places.

In the decades of back-and-forth over the future of the property, which was used as a residential center for disabled people until it was closed and vacated in 1996, Gilbert's designs have been one of several factors that town officials and prospective developers have had to consider.

According to a plan commissioned by the state Department of Energy and Environmental Protection, the state's preferred vision for the future of Seaside looks like a joint public-private operation of a hotel at Seaside that would leave the property open to the public and provide an opportunity for the state to generate revenue by renting out rooms at about $200 per night.

Gilbert experts and historic preservationists like that option, too, they wrote in a letter to DEEP officials last month, calling Seaside an "unsung monument" to Gilbert's career.

"We believe that this option is the best of all five options presented, as it would allow a path to creating a jewel of the Connecticut state park system," they wrote in an Aug. 25 letter.

The lodge plan, known as the "destination park" option, would keep Gilbert's buildings standing and reuse them as part of a hotel lodge complex.

An environmental impact study published in July compared the impact of the lodge proposal to three other proposed uses for the property: an ecological park with a nature trail, wildlife viewing areas and art installations; a passive recreation model featuring open lawns and tree groves, and a hybrid plan that incorporates part of the lodge and the two park models.

The letter was written primarily by Barbara Christen, a Cass Gilbert scholar and longtime proponent of his Seaside buildings, and was signed by 23 Gilbert experts, architects and historians. It urges DEEP to choose the lodge plan.

"Connecticut would really miss a kind of golden opportunity to create something truly special for the region," Christen said Thursday.

The group of people who worked on and signed the letter have been working together for several years to advocate for the preservation of the buildings, she said, and represent the wide range of historians and architects who see Gilbert's work in Waterford as worth saving.

"We are all watching very carefully, because it's been a meaningful project for us for a long time," Christen said. "Some of us may not be as local as others, but we feel that it would be a great loss if the buidlings were demolished or left to essentially be demolished by neglect."

The ecological park and passive recreation park options, which would lead to the buildings being demolished, are "dreadful, misguided options," they said, as is the "no build" option to leave the whole park untouched, a plan they said would constitute "demolition by neglect."

"The state would be throwing away a golden opportunity to create a special and distinctive space," they wrote.

The signatories include many members of the Cass Gilbert Society as well as two of Gilbert's great-grandchildren.

Gilbert's infirmary and nurses' building, the letter said, exemplify his skill as an architect and serve as a historical reminder of public health policy at the time before antibiotics were developed to treat tuberculosis.

Other more well-known Gilbert buildings, like the Minnesota State Capitol in St. Paul and the Custom House in New York City, have been restored, said Steven Flanders, a historian who co-wrote a biography of Gilbert with Christen.

"It's not uncommon to find good, adaptive reuse for a major structure," Flanders said.

Sharon Irish, an architectural and art historian who signed the letter, acknowledged that the preservation of the buildings is easier said than done, especially when the state has committed to funding at least part of the work.

"My sense is that for most historic preservation, the ecological thing to do is to use the buildings on the site," Irish said. But, she added, "that's not necessarily an easy call."

The most recent state-commissioned report estimates construction of the lodge would cost $39.5 million, to be shared between the state and a private hotel developer.

But, Irish added, if the buildings are to be saved, it should be done before time wears the structures down further than it already has.

"If the Connecticut state park system can make this work, and make it work fairly soon, obviously it's cheaper the sooner you address it," she said.

m.shanahan@theday.com