The Great Swamp occupies the valley between two parallel ridges. Orientated north-south, this primarily forested wetland runs nearly 20 miles between these ridges. The highlands act as a funnel, concentrating the birds towards the lowlands of the Swamp. Here in the Swamp, because the wetlands are of high quality and are for the most part unbroken and undeveloped. migrating species find both food sources and a place to rest before resuming their journeys.

The Great Swamp is an ecological treasure. With 6,768 acres, it is one of the largest freshwater wetlands in New York State. In its twenty-mile length, it traverses the municipalities of Pawling, Patterson, Southeast and Dover.

It contains two watersheds that divide in Pawling into a northflow, the Swamp River, which winds through Pawling and into Wingdale. The south flow becomes the East Branch Croton River that flows from Pawling, through Patterson and Southeast to the East Branch Croton Reservoir at Milltown Road. The Muddy Brook extension originates in the Ice Pond area and flows north from there where it joins the East Branch Croton near Pine Island.

The North and South flows of the waters of the Great Swamp

The Swamp's ecology is complex. Most of the acreage is Red maple Hardwood Swamp However, in the Southern section where the influence of the floodwaters of the East Branch Croton are stongest, a Floodplain Forest has developed. The northern and eastern fringes are characterized by herbaceous shrub and fen wetlands supported by alkaline seeps. The Muddy Brook area near Ice Pond is dominated by shrub-scrub wetland.

The Great Swamp is Part of Our Valuable Watershed

Wetlands such as the Great swamp exert major influences on water resources. The waters of the Great Swamp watershed eventually flow into the East Branch Croton Reservoir, part of the New York City Watershed System. Even more important for Dutchess and Putnam Counties, residents within the Great Swamp Watershed depend on water drawn primarily from subsurface wells partially recharged by the Great Swamp.