RMWD approves updated Warner Ranch supply assessment

The Rainbow Municipal Water District approved an updated water supply assessment for the proposed Warner Ranch development.

The Rainbow board voted 5-0, Dec. 5, to determine that the district has sufficient long-term supplies to serve the planned development along state Route 76 approximately 5 miles east of Interstate 15. The developer can use the water supply assessment to indicate to the county of San Diego, which has the discretion over subdivision maps and other land use policies that sufficient water is available for the project as part of California Environmental Quality Act review.

“That was just an update for them to finish the CEQA process,” Rainbow general manager Tom Kennedy said.

The assessment will be used in the project’s environmental impact report as well as in the county’s process to determine whether to grant a general plan amendment, specific plan amendment, rezone, administrative permit for gated access and vesting tentative map and will also be used in the process of water agencies determining whether to annex the two legal parcels not currently within the Rainbow boundaries.

The Warner Ranch development as currently proposed would include 534 single-family homes with lots ranging from 3,000 to 8,000 square feet, 246 multi-family homes or attached townhomes, a 10,000-square-foot fire station, 7.69 acres of private neighborhood parks including a clubhouse and pool, 14.68 acres of privately maintained landscape areas, a 4.23-acre public park for active recreation and 359.12 acres of preserved open space.

A water reservoir would be constructed on the western portion of the property and would

receive water from an eight-inch water line along Jeremy Way which is currently maintained by the Rainbow Municipal Water District. Water would be distributed to the project through a 12-inch line connected to the reservoir. The development would fund approximately 3,000 feet of eight-inch pipeline which would be constructed from the end of the existing line to the property’s northern boundary.

The off-site improvements also include a six-inch forced sewer main which would run from a new pump station on the site’s southwestern boundary to the west where it would connect with another new pump station, which would be provided by the Rainbow Municipal Water District.

The project would be constructed in phases. Facilities such as the fire station, the reservoir, the sewer line and drainage improvements are slated to be built in the initial phases.

The water supply assessment calculates an average water usage of 463,674 gallons per day or 519 acre-feet per year. The gallons per day estimate anticipates 267,000 for single-family homes, 73,800 for multi-family dwellings, 58,250 for the community landscape, 47,680 for the public and private parks, 8,000 for fire management zones, 7,674 for right of way and utility easements and 1,000 for the fire station.

Rainbow’s board originally approved the water supply assessment for Warner Ranch in February 2013. The 2017 water supply assessment incorporates Rainbow’s 2016 master plan and 2015 urban water management plan, the San Diego County Water Authority’s 2015 urban water management plan and the San Diego Association of Governments’ most recent population growth forecast.

“We just wanted to update it to reflect that,” Kennedy said.

The 513.49-acre Warner Ranch project consists of seven parcels, five of which are already within the Rainbow Municipal Water District boundaries and two of which are adjacent to the water district and would likely be annexed as a condition of the development. When the county updated its general plan in 2011, the Warner Ranch parcels were designated as a special study area, which requires a focused land use planning analysis to determine the most compatible and consistent land uses for the property.

The county will likely require annexation of at least one of the parcels as a condition of development; the other parcel not currently within the Rainbow Municipal Water District is designated for open space, but the desire of the Local Agency Formation Commission and the San Diego County Water Authority to avoid “islands” may result in that parcel also being annexed to Rainbow and SDCWA territory. If a parcel is annexed to Rainbow and the SDCWA, it would also be annexed to the Metropolitan Water District of Southern California, which is a complex process requiring coordination of tentative and final approvals. The annexation process would also likely add the area to the North County Fire Protection District boundaries. The annexation process would not be feasible until a tentative map is approved.