Cahuilla Indian Reservation

Client: Cahuilla Band of Indians
Project: Cahuilla Indian Reservation

The Cahuilla Indian Reservation encompasses 18,884 acres in southern Riverside County, approximately 90 miles northeast of San Diego, California. The Reservation is located within the Santa Margarita River watershed near the town of Anza. Water resources available to the Cahuilla Band (Band) include a minor contribution from Cahuilla Creek and groundwater. The Band has retained NRCE as engineering consultants to provide technical review of water rights issues in the Civil Court case in Arizona, 1247-SD-T, United States v. Fallbrook Public Utility District, et al. (Santa Margarita River Basin), and to provide engineering services to assist the Band in managing their groundwater resources.

NRCE performed a review of the Department of Justice technical experts’ litigation-level Practicably Irrigable Acreage (PIA) study, attended quarterly meetings of the Santa Margarita River Steering Committee, reviewed the Annual Watermaster Report for the Santa Margarita River, and advised the Band on issues resulting from the meetings and reports of special concern.

NRCE also conducted a groundwater study of the resources in the Anza Valley and surrounding areas of the Reservation. The purpose of the study was to quantify the existing and potential resources available to the Tribe. A test well program was a main component of the study. Aerial photographs, geologic maps, field investigations, and well logs were used to select a well site to construct a test well in the Anza Valley. Two wells were drilled as part of the program, a test well and an observation well. An aquifer pump test was performed on the test well, and the results were analyzed to determine the potential long-term yield of the aquifer. NRCE coordinated the well construction and pump test with a local drilling contractor from Aquanga, California.

NRCE prepared a water development plan that will serve as the basis for establishing the Band’s federally-reserved water rights. It establishes an agricultural water claim under the PIA standard for determining Indian reserved water rights and a non-agricultural water claim for the Cahuilla Indian Reservation. The water development plan includes an evaluation of historic and current water uses; analysis of surface water and groundwater resources; projection of future agricultural and non-agricultural water demands; preparation of a conceptual engineering design for an irrigation project; and economic analysis.