305b Ambient Groundwater Quality Monitoring in New York

 

 

Relatively little data describing the quality of groundwater in New York State exists, yet groundwater is used as a source of drinking water by approximately one quarter of the population of the state. The objective of the 305(b) groundwater quality monitoring project is to quantify and report on ambient groundwater quality from bedrock and glacial-drift aquifers in upstate New York. An ongoing cooperative project between the U.S. Geological Survey (USGS) and New York State Department of Environmental Conservation  (NYSDEC) Division of Water, this study supports NYSDEC’s responsibilities under Section 305(b) of the Clean Water Act Amendments of 1977. The resulting data set will be used to establish a groundwater quality baseline for New York State, characterizing naturally occurring, or background, conditions, and to identify long-term trends. 

 

 

Groundwater-quality samples are collected and analyzed using consistent, standardized methods. Each year, samples are collected from existing domestic and public supply wells in two to three of the 14 major hydrologic basins in New York State (excluding Long Island, which is monitored through local County programs). The groundwater sampling parallels surface-water sampling done as part of the NYSDEC Rotating Integrated Basin Studies (RIBS) program, and areas of the State are sampled once every five years. Fifty to sixty groundwater samples are collected each year from existing domestic and public supply wells using standard USGS protocols. Wells are selected to represent an approximately equal number of public and private wells, an approximately equal number of bedrock and glacial-drift wells, and to provide a representative geographic distribution of samples. Most private wells selected for sampling are identified through NYSDEC’s Water Well Program.

 

 

 

Results of the groundwater-quality sampling have shown that groundwater quality in New York State is generally good, but can vary greatly depending on local hydrogeology and land use. The most common constituents to exceed existing or proposed drinking water standards include radon-222, iron, manganese, and coliform bacteria. Examples of study-wide results are shown in figures 1 and 2 for  radon-222 and dissolved methane gas. The highest radon-222 activities detected, as much as 18,800 picocuries per liter, were found in samples collected from wells finished in crystalline bedrock. Radon-222 activities in many samples exceeded 300 picocuries per liter, part of a proposed drinking water standard, but few exceeded 4,000 picocuries per liter. Most samples had less than one milligram per liter of dissolved methane, but some samples had more than 20 milligrams per liter of dissolved methane. The maximum concentration of dissolved methane detected was more than 45 milligrams per liter in a sample from the Mohawk River Basin.

 

NYWSCStatewide