A small creek called Indian Brook flows to the Hudson River through the southern end of the sanctuary; the estuarine environment near the mouth of the creek attracts a wide array of fish, crustaceans, and amphibians, among other animals,[4] some of which are otherwise uncommon in the region.[5]
The marsh itself is estimated to be 4,000–5,000 years old.[1] It is crisscrossed by a series of channels dug in the 1830s as part of wild rice farming efforts. The site was purchased by New York State in 1969,[1] and has been managed by the National Audubon Society since 1970.[6]
Constitution Marsh sits adjacent to Foundry Cove, which was heavily polluted by industrial waste from a nickel–cadmium battery manufacturing plant that operated between 1952 and 1979.[12] In total, 115,904 lb (52,573 kg) of cadmium was released into Foundry Cove, making it "the most cadmium polluted site in the world."[13][14] Some of the metal spread to Constitution Marsh in high concentration pockets.[15] Sediment dredging efforts in the early 1970s were largely unsuccessful, and extremely high levels of both nickel and cadmium were later observed in the cove and marsh; as a result, the Environmental Protection Agency listed the area as a Superfund site in 1983. Federal remediation of the site was completed in 1995 after extensive dredging conducted in Foundry Cove.[12] Long-term sediment and water monitoring was prescribed for Constitution Marsh, as it was determined that similar dredging there would have caused disproportionate environmental damage. Additionally, the contaminants would soon be buried beneath clean sediment after the remediation of Foundry Cove.[15] Cadmium levels rapidly decreased throughout the area, and after eight years, levels of particulate and soluble metal pollutants were lower than in the Hudson River at New York City.[16]
Recreation
Recreational opportunities include hiking trails that lead to a 700 ft (210 m) boardwalk exploring the marsh,[8] and limited paddling access through the network of man-made channels.[17] The current boardwalk replaced a much shorter version in 2001,[18] and was dedicated to James P. Rod, an environmentalist who served as the warden for the sanctuary from 1982 until his death in 1998.[19] The trails and boardwalk offer expansive views of the Hudson Highlands, including Storm King Mountain and Breakneck Ridge, as well as the United States Military Academy across the river.[18]
Panorama of the marsh looking northwest in October 2012