The principal wastewater treatment plant for Bergen County, on the Hackensack River, is one of the largest wastewater plants discharging into the Meadowlands. The plant serves more than half of the county, which covers most of the Meadowlands and continues north up to New York’s state line. With almost a million inhabitants, Bergen County is the most populous county in New Jersey, the state with the highest population density in the nation (thus referred to as the most urban state in the nation). In the past, when the water treatment plant was overloaded, the county shipped sewage by barge to another treatment plant, in Newark.