Electrical resistivity tomography data collected near a groundwater replenishment and reuse project, Yucca Valley, San Bernardino County, California, 2019

Hi-Desert Water District (HDWD) is constructing a wastewater treatment plant as part of a groundwater replenishment and reuse project (GRRP) in the east hydrogeologic unit (Nishikawa, and others, 2003) of the Warren Valley Basin (7-012) (California Department of Water Resources, 2016) in Yucca Valley, CA. The HDWD plans to use reclaimed wastewater for managed aquifer recharge by spreading treated wastewater into unlined ponds at the GRRP facility. Reclaimed wastewater will percolate through the unsaturated alluvium by gravity drainage through the unsaturated zone to the water table located about 370 feet (ft) below land surface (bls). As part of the cooperative efforts between the HDWD and the USGS, the electrical resistivity tomography (ERT) geophysical surveying technique was proposed to monitor the movement of reclaimed wastewater through the unsaturated zone to the water table. This data release presents ERT data collected before water was placed into the ponds. Data from two ERT surveys (YVHDWW_L1 and YVHDWW_L2) were collected in May and September of 2019 to determine background resistivity values for the unsaturated alluvium south of the GRRP facility prior to recharge. The surveys were collected normal to each other and located downslope from the GRRP facility. This location was chosen in order to collect resistivity data in anticipation of movement of recharged water downslope through the unsaturated zone.