From the site: "This raster dataset has been created using the original data "Pennsylvania conservation gap fish habitat models" as originated by the Environmental Resources Research Institute of The Pennsylvania State University. Conservation Values were then assigned to species as determined by SmartConservation® methodology and combined to create an overall conservation value raster for fish. The resulting raster was then reclassified into 10 quantiles as follows: Old Value New Value 0 0 1-51 1 52-61 2 62-66 3 67-74 4 75-84 5 85 6 86 7 87-93 8 94-124 9 125-239 10 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 High Allegheny Plateau 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."