[en] Springs and reported spring locations within about 182 square miles of the Rattlesnake Hills in Benton and Yakima Counties, Washington, were studied for this report. One hundred twenty-five discrete locations were visited. Water was tested at 74 locations. Of the remainder, 35 were dry, 7 were iced over, and 7 were damp (too little water to sample). Two cisterns were not sampled. Eighty-three water samples from 73 springs and 1 cistern were analyzed in the field. Temperature, specific conductance, and pH were measured at each sample site. Water from each of these sources was titrated to determine carbonate, bicarbonate, and carbon dioxide contents. Seventy-one sketch maps show sample sites plus 9 other locations. Profile sections accompany the sketches where such views are informative. Altitudes of visited locations range from 700 feet to 3360 feet. Altitudes of sampled springs range from 1150 feet to 3275 feet. Discharge rates within the study area range from seeps estimated at less than one-quarter gallon per minute to a multiple-spring stream measured at about 70 gallons per minute