From the site: "This raster dataset has been created using the "Floodplains from the PA Explorer CD-ROM edition" for each county in the study area as originated by the Office of Remote Sensing for Earth Resources, Penn State University (see metadata entitled "Bucks FP.doc"). All areas designated in the shapefile were assigned a conservation value of 5. Conservation values were determined by experts gathered by Natural Lands Trust through SmartConservation®. This data set is one of several that have been combined to create an overall aquatic resources conservation value raster for the expanded piedmont ecoregion. Therefore the values were determined as a relative rank, comparable in value only to the other input aquatic resources data. Conservation value ranges from 1 - 10 with 10 being the highest value."