Higher scores indicate greater pollution risk.
This makes it hard to update the maps and the rankings as conditions change and to access the complex data that went into the rankings. Recharge data were obtained for each river basin and zone, The USDA Soil Conservation Service provided information on soil media, while data on topography were borrowed from U.S. Geological Survey maps. Information on the impact of the vadose zone was furnished by the Bureau of Economic Geology at the University of Texas. Results of the project suggest that alluvial aquifers may be more vulnerable than other groundwater systems. Atkinson says there are two major benefits of the research.