City of Santa Cruz Consultant Verifies Decline in Drought Risk

There’s a lot to say about what the Water Department’s Draft Urban Water Management Plan doesn’t include, such as water-neutral development. I’ll get to that in a minute. What’s really interesting is what the Draft says about our risk of severe curtailment during drought. The dramatic drops in water demand over the last ten years, as well as anticipated reductions in our water supply due to fish habitat needs have made a drought-risk re-assessment necessary. The report reads:

In an extreme two-year drought similar to the 1976-77 event, the estimated water supply available to the City in the second year of that event, according to the updated operations model…[is] 3200 million gallons/yr under current conditions.

This is great news. If a worst-cased drought occurred now, and customer water demand stayed at 2010 levels, there would be no water shortfall. No, there’s no mistake. City water production in 2010 was 3200 mgy—coincidently the same amount as would be available in a worst-case drought.

This estimate for our worst-case drought water supply would change somewhat if the fisheries agencies require the City to adhere to “Tier 2″ stream flows for fish habitat. The City’s current proposal to the fisheries agencies is for the City revert to “Tier 1″ flows during drought years that require curtailments of over 5%. In the event the fisheries agencies require Tier 2 flows in drought years, City consultant, Gary Fiske, has calculated that peak season drought rationing of over 25% would occur just once in 73 years—so long as demand stays at current levels.

Unless City residents are willing to incur the financial and environmental costs of a desalination plant to prepare for a 1 in 73 year event, there remains only one rationale for building a desalination plant: to accommodate growth in water demand. Growth in water demand would effectively use up the last available City water source, the reservoir, making drought curtailment more severe.

Fortunately, the strategy of water-neutral development is an idea whose time has come, adopted by our County LAFCO and soon to be considered by the County Supervisors. Soquel Creek has had a water neutral development policy since 2003. That is why their Urban Water Management Plan predicts an 8% decrease in water demand between 2015 and 2030, whereas Santa Cruz’s Plan predicts a 14% increase in water demand by 2030.

Though the bell tolls for the desalination proposal, we must address the overdraft of our streams that has resulted in drastic declines in fish populations. Besides water-neutral development, there are a host of strategies that we submitted to the Water Department to reduce our water consumption and augment supply. Most of these strategies didn’t make it into the Draft, but our hope is that Water Commissioners and City Council members will act on their stated priority of implementing all feasible alternatives before considering desalination. The Water Commission meeting on Monday, October 3, 7pm at City Hall is the first opportunity to put this principle into practice.