This report is a summary of five sites, three bituminous and two anthracite, where hydraulic mining might be technically and economically feasible. The bituminous sites were the Mid-Continent Resources, Inc., Mine near Carbondale, Colorado; the Price River Coal Company Castlegate Mine near Helper, Utah; and the Pittsburg & Midway Coal Mining Company Kemmerer Coal Mine at Kemmerer, Wyoming. The anthracite sites were the Kocher Coal Company Porter Tunnel Mine and the Frederic A. Potts & Company, Inc., property, both located in Schuylkill County, Pennsylvania. This volume contains a summary of each of the other five volumes and general remarks. The other volumes provide details about each site: a geological description of the reserves, the anticipated mining conditions, an estimate of the quantity of the reserves, the development and extraction method and necessary equipment, water system description, personnel requirements, estimated capital and operating costs, cash flow and rates of return for various selling prices, and environmental and socioeconomic considerations.