This map provides the average annual precipitation (inches) in the Spokane Valley aquifer area. The western side of the aquifer (on the Washington side) is shown to have significantly less rainfall than the eastern (Idaho) side. This drastic contrast in distribution should be considered when viewing the areal recharge. Seasonally, this area is known to have dry summers and moist winters (Molenaar, cited in Kahle 2005).

This figure provides a visualization of the aquifer's groundwater budget using a series of measurements from 1990 to 2005 (Kahle 2007). Provided in the diagram is the total groundwater flow into the aquifer, 1,471 cubic feet per second, and the total flow of groundwater out of the aquifer at 1,448 cubic feet per second (Kahle 2007). The aquifer's largest contributor is the Spokane River that sits above it. Contributing nearly a third of the recharge of the Spokane River are the neighboring lakes of the aquifer. The figure to the left provides a detailed breakdown of the individual lake contributions. Recharge from precipitation is almost equal to that of the lake recharge. Despite Lake Pend Oreille and Coeur d'Alene being quite large lakes, their contribution to the aquifer's recharge is reduced by their low permeability (Kahle 2007).