Old Pascommuck Conservation Area, on the far east side of town on East Street, comprises 4.64 acres including the E. Florence Smith nature trail. The area is bisected by the Manhan Rail Trail into two parcels of unequal size, with the substantially larger area located along the Manhan River floodplain. A parking pullout with a picnic area is on East Street, and from here a trail goes east, passing beneath the Rail Trail on an abandoned road to reach the lower portion of the area. Vegetative cover varies across the site, including a Northern Hardwood forest, Mixed Hardwood-Hemlock Forest, High Terrace Floodplain Forest, and Transitional Floodplain Forest.

 This is an example of a floodplain forest with easy public access. Though the property is small, there are several trails that cross through all the forest types. It hosts a nice variety of native plants with remarkably few invasive plants. A rare sedge has been reported in the lower portion of the property in the transitional floodplain forest. Another interesting, though not rare, plant is the native shrub bladdernut, which is abundant at the west end of the property.

Three rare animal species have been recorded as occurring in or near this conservation area. This stretch of the Manhan River is also classified as Living Waters Core Habitat.