GrokSurf's San Diego

Local observations on water, environment, technology, law & politics

A sweet water resource but there’s some salt in the mix

Posted by George J Janczyn on July 8, 2011

On average, San Diego County imports a sobering 80% of its water supply from hundreds of miles away in Northern California and the Colorado River. That figure varies though, depending on which of the 24 member agencies of the San Diego County Water Authority you’re looking at.

Take the Sweetwater Authority. If you look at a map of the Sweetwater service area sandwiched as it is between the City of San Diego on the north and the Otay Water District to the south, you might be surprised it can make do with only 41% imports. What’s the secret?

Sweetwater’s service area includes the western and central portions of the City of Chula Vista, all of the City of National City, and unincorporated areas of the County of San Diego (Bonita). But in a long sliver from the northeast flows the namesake river that’s responsible for much of the liquid wealth.

Illustration courtesy of Sweetwater Authority

For starters, Sweetwater Authority commands the surface runoff from the 230 square mile Sweetwater River watershed, beginning at Green Valley Falls in Cuyamaca Rancho State Park, about a 50-mile drive from Chula Vista. The entire watershed is fully appropriated to the Sweetwater Authority. Sweetwater also owns and operates two reservoirs in the watershed, Loveland Reservoir, and Sweetwater Reservoir, which together have capacity for over 53,000 acre feet.


Next, the Sweetwater Authority sits above productive groundwater aquifers. Its National City wells on the Sweetwater River Basin Alluvial Aquifer can supply up to 2 million gallons per day (gpd) of potable water, and additional wells drawing brackish water from the adjacent San Diego Formation aquifer are treated in a desalination facility with a capacity of 4 million gallons per day (gpd).

Looking to increase local storage capacity, Sweetwater Authority and the City of San Diego are cooperating on a proposed four reservoir intertie that could effectively allow them to share an additional 100,000 acre feet of storage without increasing reservoir size, through shared “load balancing” (my term). Some of the extra water could come from local runoff that individual reservoirs might otherwise be forced to spill during peak rainfall conditions.

As for future water requirements in the service area, the Sweetwater Authority’s 2010 Urban Water Management Plan looks forward to relative stability:

“Due to widespread conservation efforts, demands within Sweetwater’s service area have decreased over the past 25 years. Several changes in demographics are anticipated to increase water use in the future…This transition from undeveloped and formerly commercial to residential properties is anticipated to result in an increase in overall water demands within the service area. However, as new buildings replace existing buildings, water efficiency standards for toilets, showerheads, faucets, and urinals, as well as associated changes in outdoor irrigation practices to more “California friendly” landscapes, will cause the per capita water usage to decrease.”

Reverse-osmosis trains inside the facility.

There’s one uncertainty, though: a planned expansion of the Richard Reynolds Groundwater Desalination Facility.
“The Desalination Facility commenced operation in January 2000. The facility was designed to extract groundwater from four alluvial wells and five deep San Diego Formation wells, located on the north side of the Sweetwater River. A sixth San Diego Formation well was constructed in 2006. The Desalination Facility treats brackish groundwater using reverse osmosis (R/O) technology. The Desalination Facility was initially designed to produce 4.0 MGD of drinking water; however, it was constructed with space to accommodate an expansion to produce up to 8 MGD.” (2010 Sweetwater Urban Water Management Plan)

Empty pods in center would allow three more reverse-osmosis trains for a total of six.

One brackish water wellhead is just outside the door to the desalination facility.


As planned, Sweetwater’s Board did develop a plan to drill five additional San Diego Formation wells and increase capacity in the desalination facility. It certified a final Environmental Impact Report and approval for the well project last year, Feb 24, 2010.

An obstacle

The City of San Diego promptly filed a lawsuit March 26, 2010, challenging Sweetwater’s certification of the Environmental Impact Report (EIR) and approval of the project. San Diego complained that its concerns about groundwater depletion/overdraft in the San Diego Formation, saltwater intrusion, land subsidence, brine discharge, and other issues were rejected or ignored by Sweetwater.

Meanwhile it was discovered that Sweetwater’s Findings and Facts in Support of Findings had not been included on the CD distributing the EIR. The oversight meant the Board would need to again adopt the Findings and Facts and reapprove the project. This was done at the Oct 27, 2010 Board meeting.

Following this turn of events, San Diego filed a second lawsuit in order to challenge the reapproved project, Dec 9, 2010.

San Diego’s second lawsuit went further than just challenging the new EIR certification and project reapproval. It also asserted that San Diego holds Pueblo water rights to all water within the boundaries of the Pueblo, that the San Diego Formation aquifer underlies parts of the Pueblo, and that the proposed wells would tap the San Diego Formation. The City therefore asked the court for “a declaration regarding its rights to the San Diego Formation vis-a-vis Sweetwater.”

Because of overlap between the two lawsuits, the Court decided to consolidate the two cases on Dec 21, 2010.

San Diego probably feels it has no choice but to press a challenge. Presently San Diego imports 85-90% of its water. According to its Long Range Water Resources Plan (LRWRP) 2002-2030, “By 2030, the City’s reliance on imported water could be as low as 57% if most of the alternative resources options available to the City were implemented.” San Diego is investigating a number of groundwater possibilities. However, as the City’s LRWRP notes, the San Diego Formation “does not appear to recharge naturally at a useful rate.” It also observes “there could also be potential interjurisdictional and water rights issues regarding the City’s use of the basins because they extend beyond the boundaries of the City’s overlaying land.” The City’s lawsuit certainly speaks to that point.

For now, things have been quiet. At Superior Court the only thing pending is a Status Conference scheduled for Aug 12, 2011 in Dept 71, Richard S. Prager presiding.

[late word: although it wasn’t in the court record when I reviewed it last week, I just heard that there was a preliminary decision in June…that the judge agreed that there are several problems with the EIR. If correct, this could mean back to the drawing board for Sweetwater. I’ll post an update tomorrow.]


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