Estimates of impervious surface acreage for 2010 were generated for the 59-town region covered by the Piscataqua Region Estuaries Partnership (PREP). The project extended previous work done in the region for the years 1990, 2000, and 2005 and relied on the same satellite-based data sources and image processing methodologies. As a result, standardized impervious surface estimates are now available for a 20-year time period in the PREP region. The current project mapped impervious surfaces (buildings, pavement, etc.) based on a Landsat 5 Thematic Mapper (TM) image acquired on April 24, 2010. Processing used both traditional and sub-pixel image classification techniques, as described in previous efforts. The current study utilized comparable satellite imagery, and applied consistent techniques to map the PREP area for 2010.