Tucson's Clearwater Program: Recharge and Recovery of Surface Water to Bring Renewable Resources to a Growing Community

The City of Tucson has long recognized the need to reduce its historic reliance on local groundwater to meet water demand. In order to bring renewable Colorado River water into the community, Tucson Water has constructed the Central Avra Valley Storage and Recovery Project (CAVSARP) and the Southern Avra Valley Storage and Recovery Project (SAVSARP). Through recharge and recovery, Colorado River water mixes with groundwater to produce a blended water supply. Potable water deliveries from CAVSARP started in 2001 and from SAVSARP in 2008. These facilities are the primary elements of the Clearwater Program – a series of projects that bring the City’s annual allocation of Central Arizona Project water (144,191 acre-feet) into use. Implementing the Clearwater Program is the primary initiative within Tucson Water’s Capital Improvement Program over the next five years and includes the design and construction of additional recovery wells, reservoirs, boosters and transmission mains necessary to bring renewable resources into the community.

 

The benefits of recharge and recovery under the Clearwater Program are varied. The processes of soil-aquifer treatment (SAT) provide water quality enhancements by the reduction of organic carbon allowing the Utility to continue the use of chlorine to disinfection. Surface spreading recharge provides the additional benefits of short-term and long-term storage capacity to manage system demand. Using the aquifer as an enormous storage reservoir provides an operational buffer between supply availability (for recharge) and system demand (recovery). The Clearwater Program provides enhanced drought management for the community since the large-scale recharge projects can continue producing water for consumption even if recharge is ceased for long periods of time.  Unlike most other large-scale recharge projects in Arizona, the Clearwater Program utilizes a wet-water management strategy that is hydrologically sustainable and plays the central role in ensuring Tucson’s long-term, water-supply future.