In coordination with other agencies, Reclamation is addressing flow, fish passage, and screening problems in several sub-basins of the Columbia River watershed. This project involves the consolidation of two irrigation systems: the Knapp-Wham (KW) and the Hanan-Detweiler (HD) canals in the lower Entiat River basin. The purpose of the KW-HD consolidation project is to improve fish passage, conserve water, and minimize diversion operation and maintenance in the Entiat River (USBR, 2006). As part of the project, surface diversions into the HD canal were eliminated and HD water users received a replacement irrigation supply. At least one user would be switched to the KW system but most of the users would switch to private irrigation wells.

There are several domestic wells located near the proposed irrigation wells and there is concern that removal of the HD canal and new pumping stress on the aquifer could negatively impact water levels in the existing domestic wells. A groundwater flow model was developed to predict the impacts that could be expected from these hydrologic changes within the lower Entiat River basin.