The Kearny Freshwater Marsh is a 344-acre impoundment that stretches in the east from the New Jersey Turnpike Western Spur and Belleville Turnpike (Route 7) to the Keegan Landfill and Gunnell Oval Complex in the west. The former NJMC acquired the marsh in 1999. Historically, this portion of the Meadowlands was an Atlantic white cedar swamp. Human disturbance over the past 300 years had converted this area from a cedar swamp to relatively dry fields consisting of the invasive form of the Common Reed (Phragmites). Rainwater and runoff from the surrounding uplands drain into the impounded marsh.
Over many years rising water levels have reduced the extent of vegetative cover. Though referred to as “freshwater,” it is brackish with a very low salinity around 1 or 2 ppt. Freshwater wetlands are uncommon in the Meadowlands. Completion of containment of the Keegan Landfill in 2008 prevents further contamination by leachate.
Superstorm Sandy blew numerous vegetated peat islands that had been scattered throughout the marsh to the far western side, where they impede access to the water from the park at the Gunnell Oval Complex.