Hemlock Brook Preserve was donated by Walter P. Lewisohn in 1971 to The Nature Conservancy and in 2003 it was transferred to Westchester Land Trust.

The 14-acre preserve contains a deep, hemlock-lined ravine. A small stream flows through the ravine and is surrounded by a mixed hardwood forest. Great-horned owls have been seen at the preserve. An old stone fireplace and wooden bench can be found in the middle of the preserve, near the brook, and a pool of water forms at the back of the preserve, near a stone dam.

With the brook itself slicing through the hemlock ravine, it feels more like the Adirondacks than the lower Hudson Valley. The preserve is only half a mile from the Croton Reservoir and helps protect water quality in the reservoir. In June 2010, two dozen volunteers from Swiss Re in Armonk joined our staff on a beautiful day to create a new trail that loops through the preserve.