Santa Cruz Desal Alternatives Statement on Water Supply Advisory Committee Recommendations
Santa Cruz Desal Alternatives applauds the work of the City’s Water Supply Advisory Committee, and we support the Committee’s final recommendations to the City Council.
The Water Supply Advisory Committee (WSAC) recommendations include strengthened conservation practices, expanded supply capacity through regional cooperation to share and store river water underground, a backup concept to address concerns about risks in an uncertain future, and clear guidelines for assessing our progress toward long-term water security.
We are especially pleased that the WSAC recommends expansion of the 2014 Water Conservation Master Plan to more fully enable our homes, schools, and businesses to incorporate deep conservation as common sense, not sacrifice.
We strongly support the Committee’s central recommendation to increase available supply by using excess winter flows from the San Lorenzo river and replenishing our over-tapped local aquifers with water to be available during drought periods.
River-water aquifer recharge can begin this winter and build up over the next several years, allowing Santa Cruz to store more than three times the water needed for the worst-case climate-change scenario of an eight-year drought. Together with the commitment to increased conservation, this strategy can securely meet our water supply needs for the foreseeable future.
Recent scientific studies have shown the potential for this surface-water aquifer recharge strategy. For supply, there is a huge volume of winter water available that the City may capture from the river. Gary Fiske, the City’s primary water consultant, formally concluded in his report to the City’s Water Supply Advisory Committee that ”The harvesting and storage of winter flows has the potential to completely address the City’s water supply challenges and enable the City to meet projected future demands. This is the case even with current water rights, the DFG-5 instream flows [required for fish], and climate change.”
To hold that water for drought periods, the new hydro-geological measurements indicate an immense amount of underground storage capacity – “a total of over 12 billion gallons of potential storage” – available in Scotts Valley and mid-County aquifers that have been pumped down over past decades. This is four times the 3 billion gallons of added storage needed to protect against the City’s worst-case shortfall.
The aquifers can be recharged in two ways using treated winter flows. The water can be transferred to neighboring water districts for use in lieu of pumping their wells, allowing the aquifers time to recharge naturally. In addition, the water can be pumped into reverse wells for direct injection into the aquifers.
Recharging the aquifers will provide substantial benefits for natural habitat. As they refill, the aquifers will feed the regular flow levels in local streams, steadily improving conditions for fish, birds, and streamside plants. Recharging the aquifer near the coast will reverse seawater intrusion threatening to taint wells and soils. This water supply strategy will also allow the City to finally resolve longstanding negotiations with the Department of Fish and Wildlife over reserving year-round flows expressly for fish habitat in the river.
A river-water aquifer recharge system provides flexibility and water security because it can be developed in separate investment stages that cumulatively increase our water reserves. Implementation can be scaled up to expand both the amount of winter water captured and the available storage capacity utilized. The City’s goals for sufficient stored water could be achieved long before the system reaches full scale. Recharging aquifers uses low-impact technologies in common use throughout the country and adaptable to our local geology.
Even with the confidence that the river-water aquifer recharge system can provide, it is appropriate to include a backup supply plan in case unforeseen circumstances prevent the system from meeting the supply-demand gap.
The WSAC recommends investigating a backup supply from advanced treatment of wastewater, or desalination if treated wastewater doesn’t pan out. We are concerned about the public health, environmental, and energy impacts of these systems, and we would oppose any premature pursuit of either that reduces the City’s commitment to the primary river-water aquifer recharge strategy.
Any discussion of switching to a backup supply must be held in an open public process that investigates both the remaining supply-demand gap and the available options. We believe that the assessment guidelines recommended by the WSAC, combined with an involved and informed public, can provide a sensible and accountable framework for these deliberations.
Taken together, the WSAC recommendations provide an approach to water supply security that uses adaptable technologies, requires the least added infrastructure investment, uses less energy than other approaches, and provides an important added benefit of cumulative habitat enhancement. It is an environmentally sensitive approach ideally suited to the natural resources of our setting and consistent with Santa Cruz values. This is a water-supply strategy that everyone in the community can support.
We urge the City Council to adopt the WSAC recommendations, and we are committed to doing our part to see that the full potential for conservation and river-water aquifer recharge is realized.
— Santa Cruz Desal Alternatives, November 1, 2015