Yeager Well Replacement Project

GSWC is planning to construct and operate replacement potable water supply well, Yeager Well 4, at its Yeager-Vale Plant. Yeager Well 2 will be decommissioned once Well 4 has been established. An adjacent GSWC-owned parcel to the south (APN: 058326107) has been identified by GSWC as the proposed location for the replacement well. The parcel is approximately 130 feet (east to west) by 100 feet (north to south). The addition of the parcel to the south would expand the total area of the Yeager-Vale Plant to approximately 0.77-acre. The Proposed Project would be part of GSWC’s Morongo Del Sur System, which delivers groundwater pumped from the Morongo Valley portion of the Morongo Basin located east and west of the Twenty-Nine Palms Highway between Morongo Valley and Yucca Valley. GSWC is proposing to decommission Yeager-2 once Yeager Well 4 has been established. Yeager-2 is approximately 300 feet deep, and the new Yeager-4 well would reach approximately the same depth. The facility would not require a crew or staff; therefore, no bathroom facilities would be built. The southern parcel, Parcel B, of the Project Site is undeveloped land, with mesquite dominated vegetation and cottonwood tree (Populus sp.) towards the eastern side, and overhead power lines parallel to the northern property line between the southern parcel and the Yeager-Vale Plant. The overhead power lines proceed north along the eastern perimeter of the Yeager-Vale Plant. As part of the construction, the vegetation and the large cottonwood tree will need to be removed and the ground leveled and prepared (i.e., temporary gravel bed) for heavy equipment prior to construction activities. The cottonwood tree measures 25 feet tall and has a 14.6-inch diameter at breast height (DBH). The Project ingress/egress would be on the western property boundary from Vale Drive (see Figure 3). The Yeager-Vale Plant has several permanent structures that would be protected in place: the Yeager-Vale Plant treatment building, generator, motor control center, and chemical building. The existing onsite discharge pond located on Parcel A would also remain in place. To manage excess water volumes generated during the well development phase that exceeds the capacity of the existing discharge pond, a temporary above-ground high-capacity discharge pipeline would be installed. The line will extend east along Mojave Drive and then continue north along East Drive before terminating south of the East Drive and Covington Drive intersection, with the line discharging into an upland area (see Figure 3). The pipeline would span approximately 500 linear feet and be completely contained within the developed roadway and shoulder of Mojave Drive and East Drive. This alignment has been selected to avoid encroachment on wetland habitat within the Big Morongo Canyon Preserve. GSWC maintains regulatory coverage for this discharge under the State Water Board National Permit Discharge Elimination System (NPDES) Permit for Drinking Water System Discharges (Order No. WQ 2014-0194-DWQ, WDID No. 4DW0623), administered by the State Water Board Division of Water Quality. In June 2015, GSWC received a Notice of Applicability (NOA) for the Statewide Drinking Water System Discharge Permit, identification number 4DW0623, which asserts coverage under Order No. WQ 2014-0194-DWQ. Under this NOA, GSWC is authorized to discharge water from GSWC’s Morongo Del Sur Drinking Water system into the Big Morongo Creek (located within the Big Morongo Canyon Preserve). To ensure NPDES permit compliance, two temporary settling tanks would be deployed on Parcel B to remove suspended solids, reduce turbidity, and decrease flow velocity prior to discharge. These tanks operate based on gravitational sedimentation principles and serve as a best management practice for the discharge. The temporary discharge pipeline and settling infrastructure would be fully decommissioned and removed upon completion of construction activities. The highest pumping rate at Yeager-2 was 415 gallons-per-minute (gpm) when measured in 1990, and the pumping rate has declined nearly 50 percent in recent years. Yeager-4 is anticipated to have a capacity of 300-400 gpm. Pumping rates would be determined during drilling and are impacted by several factors including well interference at the well field, the nearby domestic wells across the street, and water quality. To meet the local noise ordinances, 24-foot-high sound walls would be required during well drilling. It is expected that the Project Site would need to be partially enclosed with sound walls strategically placed to minimize impacts to sensitive receptors to the west and south sides of the Project Site. Project construction, consisting of grading, well drilling, and equipping, would begin in August 2025 and take approximately five to six months to complete. Drilling would occur for approximately 150 days. Some components of the well drilling would require 24-hour operations. This is to advise that the State Water Resources Control Board (Lead Agency) approved the above-described Project on October 27, 2025 and has made the following determinations regarding the above-described Project: