Assessment of the sensitivity of Missouri reservoirs to acidification

We used water quality information from 103 Missouri reservoirs to assess their sensitivity to acidification from acidic atmospheric deposition. Total alkalinity less than 20 mg/L or a Calcite Saturation Index (CSI) of 1.0 or greater were the criteria to classify reservoirs as sensitive to acidification. Most of the reservoirs (83 of 103) would be considered circumneutral, hard water systems with high acid neutralizing capacity. Thirteen reservoirs were sensitive to acidification based on alkalinity or CSI. Four reservoirs with both low alkalinity and high CSI are located in southeast Missouri in areas of igneous rock outcroppings or chert deposits in limestone formations. These reservoirs are small (