Nearly all the water consumed within the eastern Palouse River Basin is groundwater; currently no significant usage of surface water occurs. Groundwater in the Palouse River Basin is generally pumped from two basalt aquifer systems, both part of the regionally extensive Columbia River Basalt Group. These are the shallow Wanapum Aquifer, the primary water supply for rural residents of Latah County and parts of Whitman County, and the deeper Grande Rhonde Aquifer, the primary municipal drinking water source for the cities of Moscow, Pullman, Colfax, and Palouse. It is important to note that there are significant differences in the geology from east to west across the eastern Palouse Basin, which may impact local aquifer characteristics. For instance, sedimentary interbeds between basalt flows are much more abundant beneath Moscow than beneath Pullman, and thus comprise a significant volume of the aquifer system in the eastern part of the basin (see figure below). |
 Hand pump well
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