As of this date, the Desal Alternatives group has developed this statement on the WSAC proposal for aquifer recharge:
Santa Cruz Desal Alternatives strongly supports the proposed regional water security strategy of storing excess winter flows from the river in over-tapped local aquifers, to be available during drought periods.
The surface-water aquifer recharge strategy 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. This strategy, together with Santa Cruz’s commitment to conservation, will 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 wells for direct injection into the aquifers. Both ways use low-impact technologies adaptable to local terrain.
Security and Habitat Benefits
This strategy provides flexibility and water security because it can be developed in separate investment segments 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, and the City’s goals for sufficient stored water would be achieved long before the system reaches full scale. Because it can be implemented in multiple ways and in several separate aquifers, this strategy has the compelling advantage of having its own built-in fallbacks and redundancies that assure Santa Cruz has the level of water security it needs.
Recharging the aquifers will also provide substantial benefits for natural habitat. As they refill, the aquifers will feed the regular flow levels in local creeks and the river, steadily improving conditions for fish, birds, and streamside plants far more than anything else we could do to improve those stream habitats. Near the coast, injected water will block intruding seawater from tainting wells and soils.
The City should be prepared in case future changed conditions lead to consideration of supplementing the surface-water aquifer recharge strategy.
With long-term uncertainties about future changes in technology, energy costs, climate, economic conditions, and demographics, the type of supplemental supply best suited to the new conditions is unknown at present. It would therefore be premature and unnecessarily costly to select any specific approach now.
Specifying a supplemental approach now could also be divisive as it would risk jeopardizing public support for the main plan, particularly if significant public funds were to be invested toward a “Plan B” that has doubtful public acceptance.
Instead, if clear need arises in the future, the City should commit to an open public process to investigate the latest options in water management and treatment technologies in light of energy costs, water quality and environmental regulations, updated demand estimates, and community priorities at that time. Any resultant new plan involving significant public investment should be subject to approval by the voters.
Storing available winter surface flows by recharging aquifers 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.
— Santa Cruz Desal Alternatives, September 5, 2015