A San Diego County Water Authority (SDCWA) Board of Directors special workshop on the Carlsbad Seawater Desalination Project was held Thursday, June 14.

On the agenda for the informational workshop was a) integration of the Carlsbad Desalination Project into existing infrastructure, b) examination of the range costs with comparisons to the unit cost of alternative local supplies, and c) incorporation of costs related to desalinated water from Poseidon’s Carlsbad plant into the Water Authority’s rates and charges.

Although it was an informational workshop, not a decision-making meeting, there were several people who took advantage of the public comment period before the session began, including Nate Cooper and Julia Chunn-Heer (representing the San Diego chapter of Surfrider Foundation) who encouraged that more effort be used on soliciting public input on desalination and that Indirect Potable Reuse (aka IPR, aka purified recycled water) be given a much higher priority than it now has in SDCWA’s strategic thinking.

Water Resources Director Ken Weinberg was the main speaker at the workshop. The first segment was to explain SDCWA’s efforts at “Balancing Treated Demand and Annual Contractual Commitment.”

SDCWA, being the water wholesaler to 24 member agencies in San Diego County, sells/provides both treated and untreated water. Approximately 60% of its deliveries are untreated water, 40% treated water. The desalinated water from the Poseidon Carlsbad facility is treated water. The question is how to integrate the treated desal water into the existing treated water infrastructure delivering that 40%.

Presently SDCWA gets its treated water via existing contractual (and even mechanically built-in*) requirements to buy a minimum amount of treated water from MWD (via the Skinner Water Treatment Plant) and needs to produce a minimum amount at its own Twin Oaks Valley WTP.

The Authority also provides treated water indirectly through arrangements with individual member agencies such as Helix Water District and the City of San Diego (who buy untreated water and treat it themselves) to provide treated water to areas that SDCWA can’t reach with its own infrastructure.

The prospect of SDCWA using the Poseidon Desalination facility as a new source of treated water meant that the countywide demand for treated water needed to be thoroughly analyzed, including study of local hydrology, seasonal variation, and projected future demand.

The goal: optimize the use of all regional treated water facilities and figure out what the Water Authority’s contracted annual minimum deliveries from Poseidon should be.

At one point it was acknowledged that the City of San Diego’s potential use of IPR wasn’t taken into account in the demand study because the city buys only untreated water from SDCWA and does its own treatment, i.e., if San Diego produces IPR water for itself there would be no effect on countywide demand for treated water.

Director Keith Lewinger picked up on this and made an interesting point that was startlingly obvious even though some of us may not have really considered it: if San Diego engages in a large-scale IPR operation it will buy less untreated water from SDCWA which could be financially harmful to SDCWA.

(The implication, in my view, is that this could influence just how much wholehearted support San Diego gets from SDCWA for implementing IPR on a large scale. Also, it seems to me that things will be quite complicated on many levels because San Diego’s purified recycled water (IPR) would reside in the San Vicente Reservoir but SDCWA will own the rights to the reservoir’s additional capacity when the dam raise project is completed. Many issues and kinds of water will be all mixed up.)

The second portion of the workshop focused on costs and how they would be incorporated into rates and charges. This part of the study is also extraordinarily complicated but I’ve no time or space to give justice to the breadth of that discussion.

Bradley Fikes gives the costs and rates issue a closer look in his North County Times story “Desal project would raise average water bills 7 percent“. Mike Lee’s U-T San Diego article “Carlsbad desal plant, pipe costs near $1 billion” chimes in on the issue.

The agenda, full audio recording of the workshop, and the presentation slides from the June 14 meeting are available on SDCWA’s website [link].

Note this was an informational workshop, not one where decisions were made. Check the presentation slides mentioned above. The last slide shows Next Steps listing future meeting dates and topics to be addressed (and opportunity for public commment, I hope) over the next several months.

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* Mechanical, in that the meter/valve on the treated water pipeline incoming from MWD cannot measure the amount of flow if it is below the minimum contracted amount. If less is taken, payment for the full amount is still required.