Overview

Groundwater-quality monitoring data collected by NAWQA from many regions of the United States are being synthesized into a national assessment of groundwater-quality trends. Between 1988 and 2000, NAWQA completed groundwater-quality assessments in 51 study areas across the United States. During 2001, NAWQA began resampling many of those well networks on a near-decadal timeframe to determine if groundwater quality has changed over time. A well network is typically 20-30 randomly selected wells designed to examine groundwater quality in a region; in some cases well networks are designed to represent specific land-use practices such as agricultural or urban. To date (2012), 1,235 wells in 56 well networks have been resampled on a near-decadal time period (Lindsey and Rupert, 2012; Rupert, 2005). NAWQA will continue to periodically resample wells.