GrokSurf's San Diego

As the threat of water shortages recedes in the public mind (for the time being), the fact remains that the San Diego County Water Authority (SDCWA, or the Water Authority) has to import roughly 80% of the county’s water requirements. As worrisome as such heavy dependence on the outside is, what makes water planners and managers even more uneasy is that the cost of imported water is rising with no end in sight and the availability of outside water is increasingly threatened by environmental and regulatory circumstances. Reducing dependence on imports is therefore a growing priority.

That’s definitely true in the case of Chula Vista, where the Otay Water District (OWD, or Otay) currently must meet all its potable demand with imported treated water from SDCWA. Actually, OWD’s service area isn’t just Chula Vista, it includes parts of southern El Cajon and La Mesa, Rancho San Diego, Jamul, Spring Valley, Bonita, eastern City of Chula Vista, East Lake, Otay Ranch and Otay Mesa areas.

In 2005 OWD delivered about 40,000 acre-feet (by comparison, the City of San Diego delivered about 199,000 acre-feet) although effective conservation measures over the past two years have reduced those numbers.

OWD has virtually no local water resources of its own. Some people might point to the Lower and Upper Otay reservoirs in Chula Vista but those belong to the City of San Diego.

Following the great 1987-92 drought, OWD in 1994 established a goal of being able to meet 40% of annual demand from local water sources if water becomes unavailable from the Water Authority. It signed agreements with the Helix Water District and the City of San Diego for access to treated water from those systems. It aggressively moved to promote recycled water use and required dual piping for new developments (one set for potable, one for recycled irrigation). Otay now maintains the largest recycled water distribution system in the county. It supplies the recycled system from its Ralph W. Chapman Water Recycling Facility and from San Diego’s South Bay Water Reclamation Plant.

The District is now directing a groundwater well project within the master-planned Rancho Del Rey community located a few miles east of I-805 and north of H Street.

It turns out that in 1991 when the McMillin Development Company was building in the neighborhood, it drilled a 7-inch well to 865 feet to produce water for dust control and soil compaction. After construction the company had no further need for the well and put it up for sale.

OWD purchased the land and well in 1997 and explored its potential as a potable water source. It appeared that a reasonable amount could be produced, but the water was salty and of poor quality, requiring reverse-osmosis desalination. After reviewing design and construction cost estimates in 2002, the District decided it could not justify the expense at that time so it suspended the project and waited.

By 2010, the cost of imported water had been rising dramatically and price increases projected to continue. Looking again at the well project, estimates came in at about $1500 per acre-foot. This time Otay decided it would be economically viable and the Rancho Del Rey Well Project was underway.

In September 2010 a new 12-inch well was drilled to 900 feet and testing revealed the well had the potential to produce 500 acre-feet of water per year (AFY).

A few weeks ago on June 16, 2011 the District held an open house to explain the project and show architectural renderings to neighborhood residents and other interested individuals.

The reverse-osmosis treatment facility design will feature architecture and materials to mirror the appearance and character of the residential and institutional structures in the vicinity of the site. The well site is adjacent to a large child daycare facility and the relatively new neighborhood is comprised of mostly single family residences. There are spacious parks, schools, and other public facilities nearby.

Proposed design for the water treatment facility

New connections to a District water main will include an inlet for blending well water with potable water and an outlet for distribution of the blended water into the system. Brine generated in the treatment process will be discharged into the City of San Diego’s sewer system in compliance with requirements of the National Pollutant Discharge System (NPDES), San Diego Wastewater Department, and the County Department of Environmental Health.

The environmental impacts and a detailed project description were published in a Mitigated Negative Declaration following CEQA guidelines.

Otay estimates that operations of the 500 AFY well could begin by April 2013.

Otay is also looking into the feasibility of purchasing desalinated seawater from a proposed reverse osmosis plant that is planned by a private developer for Rosarito Beach, Mexico.

The County Water Authority is also conducting a feasibility study of obtaining desalinated water from that facility, but Otay is evaluating conveyance and treatment options for itself and negotiating separately with the parties in order to produce a Principles of Understanding document for establishing water supply resource acquisition terms.

For additional information about the above projects and much more, please see Otay’s 2010 Urban Water Management Plan.