Abstract: The New Jersey Meadowlands Commission (NJMC) has determined that remediation of the Kearny Marsh freshwater ecosystem is a high priority and partnered with Rutgers University to achieve this goal. Since the marsh was formed almost forty years ago, it has been negatively impacted by activities that have altered its hydrology (ditching, urban stormwater infrastructure, construction of the western spur of the New Jersey Turnpike). Contamination of the marsh sediments with heavy metals, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) has been well documented. A bulkhead that is conveying Frank’s Creek stormwater between the Town of Kearny and the Passaic River has also been breached, allowing for water exchange with the marsh. The primary goals of this project were to characterize the existing hydrology of the Kearny Marsh, evaluate current transport of contaminants into the marsh from the highly urbanized surrounding land uses, to predict effects on marsh hydrology of proposals to redevelop and reuse the site, and to project future marsh water levels under drought and high precipitation conditions. Stormwater and groundwater analyses were conducted for nutrients, PAHs, PCBs, heavy metals, and volatile organic compounds (VOCs). Results show elevated levels of heavy metals and, in some locations, PAHs and PCBs. Ammonia and phosphorus were elevated during all sampling events, indicating the potential for a high degree of future eutrophication of this ecosystem. Principal component analysis and other analytical techniques (contaminant ratios, ANOVA, and ‘fingerprinting’) were used to determine possible source(s) of elevated contaminant loadings. To analyze various components of this complex system, a Storm Water Management Model (SWMM), surface water model and a Visual MODFLOW groundwater model were developed for the marsh, calibrated, and verified. The validated SWMM and MODFLOW models were utilized to simulate the effects that construction of a slurry wall around the Keegan Landfill and redevelopment of portions of the wetland will have on the overall Kearny Marsh hydrology.