The irregularly shaped scenic pool has been restored.

The circle leading to the pool now has tinted concrete and exposed stone aggregate, mimicking the original crushed shale that the designer wanted to be stained yellowish-orange.

And paper birch, eastern hemlock and northern spy apple trees chosen by the master architect for the home grounds have been planted.

The changes completed this week at the Graycliff Estate in Derby restore one of the rare landscapes that Frank Lloyd Wright actually designed by hand over a prolific career that spanned more than half a century.

“We are thrilled with the completion of this important landscape project,” said Reine Hauser, Graycliff’s executive director. “The restoration is a very significant step forward for Graycliff, and for historic landscape architecture in the United States.”

The work, which cost about $650,000, was guided by the nonprofit Graycliff Conservancy, established in 1997 to acquire, preserve and restore the eight-acre estate, including the main building, the Isabelle R. Martin House.

Larkin Soap executive Darwin D. Martin and his wife, Isabelle, commissioned Wright to build their summer home at Graycliff, which members of the family inhabited from 1927 until the mid-1940s.

Wright designed the pool to echo Lake Erie when the estate was completed in 1931. It was filled in decades later, and volunteers dug it out about 10 years ago. The pool and fountain now have a double concrete liner, new circulation system and historically accurate plantings.

The circle leading to the pool and the drive leading to it also have been restored to look like the earlier time, with the new materials recalling the original crushed shale. The changes were made to eliminate shale dust from being tracked through the buildings and to make the path more handicapped-accessible. New, accurately sized boulders have also been added around the pool.

In addition, a stair tower endangered by ice and winter storms off Lake Erie has been protected by temporarily removing a bridge for storage and future restoration. Nonhistoric trees and shrubs were removed, replaced by trees, shrubs and lawns that Wright originally called for.

More work on the interiors of the buildings will now take center stage, Hauser said, although there is no timeline or projected completion date.

“We’re probably about 80 percent done, because all the structural work, including building exteriors, has been completed on all three buildings. We now see the light at the end of this tunnel,” Hauser said.

The work was aided by Heritage Landscapes of Vermont and Connecticut, which prepared a Cultural Landscape Report on what the estate looked like when it opened, and determined that architect Ellen Biddle Shipman had later designed an Arts & Crafts-style garden. Drawings and construction supervision were done by Pressley Associates of Boston, and the contractor was Catco.

The estate is on the National Register of Historic Places and is a designated New York State Landmark. For details on touring Graycliff Estate, see http//: