The overall service review and sphere study area is located in the south desert portion of the County. It is generally east of the Yucca Valley community, south of the Twentynine Palms Marine Corps Air/Ground Combat Center, west of the Twentynine Palms community, and north of the Joshua Tree National Park.
Service Reviews and Sphere Updates were performed for the following districts:
- Joshua Basin Water District
- County Service Area 20
Service Reviews were also performed for the following improvement districts:
- County Service Area 70 Zone R-19
- County Service Area 70 Zone TV-5