1. Background Information about Long Island Groundwater

Groundwater, stored in underground aquifers, is an important resource on Long Island because it is the primary source of drinking water for residents. However, groundwater quality has been deteriorating partly due to lack of wastewater treatment combined with a growing population density. In fact, 74% of Suffolk county homes are not sewered and use cesspools or leaching fields which leach contaminants into the ground. Wastewater derived nitrogen, specifically nitrogen in the form of nitrate, is a major source of groundwater contamination on Long Island. In the 1970’s, prior to contamination, pristine groundwater had ≤0.05 milligrams nitrogen per liter. As of 2013, Upper Glacial Aquifer groundwater had an average of 3.44 milligrams nitrogen per liter. While average groundwater nitrate values have more than tripled within several decades, specific areas of Long Island have more severe nitrate contamination and some wells in Nassau and Suffolk county have been closed due to concentrations exceeding Environmental Protection Agency regulations.

  1. Consequences of Groundwater Contamination

The EPA regulates nitrate concentrations in drinking water and sets a limit of 10 milligrams nitrogen per liter because nitrate along with other risk factors have been linked to infant deaths and cancer in adults. Pregnant women, infants, and elderly people are at highest risk for nitrate related health effects. Currently Suffolk county mixes groundwater from different locations to meet EPA drinking water guidelines but this measure does not help improve water quality in the long term. Wastewater derived nitrogen not only impacts drinking water, it also enters coastal water through submarine groundwater discharge. Groundwater slowly moves from higher elevation towards the coast and it discharges into surface seawater where it is a major contributor to nitrogen pollution. There are several consequences of nitrogen pollution such as decreased water quality, increased algae biomass, tendency towards harmful algae blooms, low oxygen concentration, and marine animal mortality. These consequences negatively impact the fishing industry as well as the tourism industry. Decreased water quality is also linked to decreased housing prices.  Overall, wastewater derived nitrogen pollution of groundwater and coastal water is a serious health concern and is currently impacting local marine ecosystems as well as resident recreation. Furthermore, the increase in groundwater nitrate over a short period of time is alarming due to the human health effects as well as the economic implications for contaminating and remediating the region’s primary source of drinking water.