CAP has developed seven recharge projects and currently operates six (Avra Valley was sold to Metro Water in 2010). The Tucson Active Management Area (AMA) recharge facilities currently have a cumulative recharge capacity of 80,000 acre-feet per year and include the Pima Mine Road and Lower Santa Cruz Recharge Projects. In the Phoenix AMA, there are four existing facilities: the Aqua Fria, Hieroglyphic Mountains, Tonopah Desert, and Superstition Mountains recharge Projects, with a combined annual permitted capacity of 341,500 acre-feet per year.
|PERMITTED RECHARGE CAPACITY|
|Project Name||Year Complete||Permitted Capacity|
|Avra Valley||1996-97||Sold to Metro Water in 2010|
|Pima Mina Road||1998-99||30,000|
|Lower Santa Cruz||2000||50,000|
Recharge Program Goals
Recharge is a long-established and effective water management tool that allows renewable surface water supplies, such as the Colorado River, to be stored underground now for recovery later during periods of reduced water supply.
The water management benefits of recharge include the following:
- Encourages the use of renewable water supplies instead of continued over-reliance on finite groundwater supplies;
- Mitigates impacts of groundwater overdraft including subsidence and increased power costs for pumping water from greater depths;
- Firms Arizona's water supply by providing a "reserve" of water that can be recovered during prolonged drought or during interruption in the water delivery capability of the Central Arizona Project (CAP) aqueduct;
- Eliminates the need to construct costly surface reservoirs that are prone to excessive evaporation losses in Arizona's arid climate;
- Provides an alternative mechanism to deliver CAP water through recharge and recovery instead of constructing costly water treatment plants and distribution facilities;
- Improves the quality of recharged surface water by filtration through underlying sediments in a process known as soil aquifer treatment.
CAWCD Recharge Program History
Soon after receiving authority in 1986 to conduct recharge feasibility studies, CAWCD implemented two studies to identify favorable locations to develop recharge projects along the CAP aqueduct. Opportunities for Groundwater Recharge in Central Arizona, 1987, was a reconnaissance level feasibility study report that identified potential recharge sites along the entire length of the CAP between the Colorado River and Tucson. Butler Valley Underground Storage and Recovery Project, 1987, was a site-specific investigation report to assess the hydrologic feasibility of constructing a large-scale recharge project in the Butler Valley, an alluvial basin located in western Arizona. Although these studies investigated numerous potentially favorable sites, they did not result in development of a project.
In the early 1990's, CAWCD recharge efforts primarily focused on development of Groundwater Savings Facilities (GSF) also known as "in-lieu" or "indirect" recharge as a means of encouraging the direct use of CAP water instead of continued over-reliance on groundwater supplies. In general terms, a GSF is a water exchange authorized under State law where the operator of the GSF (typically an irrigation district) will substitute renewable surface water (CAP water) for groundwater that it has a legal right to pump. This substitution of surface water for groundwater essentially "saves" groundwater that would have been pumped and is legally considered analogous to direct recharge. The customer storing at a GSF receives long-term storage credits that can later be recovered and not counted as groundwater pumping.
Beginning in 1992, CAWCD acquired the necessary regulatory permits from the Arizona Department of Water Resources (ADWR) and entered into agreements with eleven different irrigation districts to deliver excess CAP water for agricultural irrigation in-lieu of pumping groundwater. In return, CAWCD earned long-term storage credits that can be recovered during future water supply shortages. Under this program between 1992 and 1999, CAWCD accrued approximately 645,000 acre-feet of long-term storage credits in its three-county service area.
In 1990, legislation passed authorizing CAWCD to develop State Demonstration Recharge Projects and established the State Water Storage Fund to finance development of these projects with revenues derived from a property tax collected in Pima and Maricopa Counties. The purpose of the State Demonstration Project statutes was to allow for construction of permanent, large-scale underground storage facilities for direct recharge of excess CAP water. These facilities provide a means of storing excess CAP water not currently used by CAP subcontractors for future recovery during periods of severe water shortages. State Demonstration Projects are also used for replenishment purposes by the CAGRD. Additionally, cities and private water companies utilize these projects for compliance with the State Assured Water Supply requirement. Finally, the Arizona Water Banking Authority (AWBA) stores water at State Demonstration Projects to firm the water supply of CAP municipal and industrial subcontractors against future shortages and for interstate water banking purposes.
Property taxes collected between 1991-1996, along with interest revenue, resulted in $33.7 million for the benefit of Maricopa County and $8.5 million for Pima County State Demonstration Projects. With the formation of the AWBA in 1996, CAWCD annually determines whether to direct revenues from the property tax to the AWBA to fund groundwater recharge and other AWBA activities. All property tax revenue collected since 1997 has been directed to the AWBA.