Estimates of 2015 impervious cover (IC) for the 52 towns of the Piscataqua Region Estuaries Partnership (PREP) were generated from 2015 1-foot imagery (for the 42 towns in NH) and 2015 1-meter NAIP imagery (for the 10 towns in Maine). The 2015 IC mapping updated previous high resolution mapping developed from 2010 (New Hampshire) and 2011 (Maine) orthophotography for the study area.
Impervious features covered 32,462 acres (5.8% of the land area) in the New Hampshire towns and 13,295 acres (5.3% of the land area) in the Maine towns, with a total of 46,634 (5.6% of the land area) acres mapped in the entire study area. The towns with the highest percent impervious cover in 2015 were in New Hampshire, and included Portsmouth (26.7%), New Castle (20.0%), and Seabrook (20.0%). The largest increases in IC between 2010 and 2015 occurred in Rochester, NH (122 acres), Wells, ME (64 acres), and Seabrook, NH (64 acres). Minimal amounts of IC increases occurred in most towns, with the least amounts in Madbury, NH (4 acres), New Castle, NH (2 acres), and Brookfield, NH (2 acres).
Justice, David and Rubin, Fay, "Developing 2015 High-Resolution Impervious Cover Estimates for the 52 Towns in the Piscataqua Region Estuaries Partnership: Final Report" (2017). PREP Publications. 395.