Feasibility of recharging basalt aquifers in the Walla Walla area, Washington

Abstract

This report presents the results of a study made as a part of the cooperative investigation of the ground-water resources of Washington being made by the U. S. Geological Survey and the State Department of Conservation, Division of Water Resources. It describes the factors affecting the feasibility of artificially recharging the basalt aquifers in the Walla Walla area with water injected through wells. The study resulted from a request to the Department of Conservation from the city of Walla Wall, but its results will be of interest in areas of similar aquifers throughout the State. The city of Walla Walla has been considering for several years the possibility of recharging basalt aquifers by introducing water into wells tapping those aquifers. The water-supply system of the city is easily adaptable to such a recharge program. During at least a part of the year water from Mill Creek is available for recharge. Also, one of the wells (city well 3) is only a few feet from the pipeline carrying Mill Creek water to the city's reservoir, so that installation of the required piping and metering equipment would be simple and inexpensive. Although recharging operations and experiments have been conducted for many years in the United States and abroad, almost all have dealt with sand and gravel aquifers. At a very few places basalt aquifers have been recharged through wells, but so far as is known no controlled tests or experiments have been made to determine the effectiveness of the process and the limitations or controlling factors, in recharging basalt aquifers. The immediate object of this report is to assemble all pertinent data and to present it in such form that it can be used effectively by officials concerned in making decisions as to the feasibility of a program of groundwater recharge using city well 3 at Walla Walla as an injection well.