About this map:

This map shows the approximate locations of observation wells used for monitoring of water in the Northern Guam Lens Aquifer (NGLA). The source of the geospatial information used is the National Water Information System (NWIS), operated by United States Geological Survey (USGS). Raw data in the form of geographic coordinates were obtained from NWIS (http://waterdata.usgs.gov/gu/nwis/nwis) and converted to a shapefile.