Ground Water Resources in a Portion of Payette County, Idaho

This study was conducted to provide ground water resource information for Payette County, Idaho. The study area is located in the western edge of a large sediment filled basin, the western Snake River Plain, which consists of over 4,000 feet of lacusterine and fluvial deposits of mostly clay, sand and gravel. Wells and aquifer identification are Lithologic correlation between difficult because of the discontinuous and variable nature of the sediments. Four water quality types were identified from 42 ground water analyses. Four flow systems are suggested when the four water types are correlated with the subsurface geology. Well hydrographs indicate that the dominate source surface water irrigation in much of the study area of recharge is long-term water level trends are stable in the surface water irrigated areas. Multi-year hydrographs are not available to determine long-term trends in the ground water irrigated areas. One irrigation well has experienced over 4 ft/year of water level decline. Most of the ground water enters the study area from the southeast with a small quantity entering from the northeast. Most ground water discharge is to the Snake and Payette Rivers. Drinking water standards for sulfate, iron, manganese, nitrates and total dissolved solids are exceeded for water quality samples from some wells. The south edge of Clay Peak is identified as a potential problem area for future housing expected. The short development because of well life problem for the low well yields the City of Payette is possibly because of bacteria indigenous to the subsurface