CAP Water becomes essential to Oro Valley's Water SupplyOro Valley’s water supply was not created through a single project or decision. It is the result of decades of planning, investment and regional cooperation. In this two-part series, LOVE examines how that system developed. Today, we look at how Central Arizona Project water became an essential part of Oro Valley’s supply.
First came the water rights
The Central Arizona Project canal reached the Tucson area in 1991, but CAP water did not begin flowing into Oro Valley’s system for another 21 years. Before that could happen, the Town had to secure the right to receive it. Oro Valley obtained its current annual allocation of 10,305 acre-feet through four transactions: 1,652 acre-feet with the 1996 purchase of the Cañada Hills Water Company; 642 acre-feet when it assumed management of the Oro Valley Water Improvement District in 1999; 4,454 acre-feet through a 2002 settlement with Tucson at a cost of approximately $5.96 million; and another 3,557 acre-feet through a federal and regional reallocation agreement in 2007.
Tucson Water provided the delivery route
Owning CAP rights did not solve the delivery problem. Building a separate treatment plant and pipeline system would have been enormously expensive, so Oro Valley reached an agreement with Tucson Water. Under that arrangement, Tucson Water recovered and treated CAP water and moved an equivalent amount through its existing system to connections with Oro Valley, a process commonly called “wheeling.” The first connection was completed in 2012, when approximately 1,283 acre-feet of CAP water were delivered to Oro Valley customers and groundwater pumping fell by approximately 1,573 acre-feet—more than 500 million gallons—compared with the previous year. Additional connections completed in 2014 and 2018 increased the amount of CAP water the Town could receive.
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Oro Valley did not have to deliver its entire CAP allocation directly to customers. Water not immediately needed could be sent to regional recharge facilities and stored underground. Some could be recovered during the same year to offset groundwater pumping, while water stored for more than a year generated long-term storage credits. Those credits give the Town the legal right to recover an equivalent amount from permitted wells in the future. By the end of 2025, Oro Valley had accumulated an estimated By the end of 2025, Oro Valley had accumulated an estimated 39,908 acre-feet of long-term storage credits. That is equivalent to approximately 13 billion gallons of water, enough to supply about 144,500 typical households for one year, based on the Town’s estimate of 7,500 gallons per household per month. For customers, the credits function much like a water savings account: a shared reserve for droughts, emergencies and possible reductions in CAP deliveries.
Groundwater remains a key part of the system
CAP water did not eliminate Oro Valley’s use of groundwater. Wells remain an important part of the Town’s water portfolio. The difference is that groundwater is no longer the Town’s only major supply. Oro Valley now relies on a combination of groundwater for drinking-water service, CAP water delivered through Tucson Water or stored and recovered from regional recharge facilities, and reclaimed water [see note] used primarily for golf courses and other large irrigated areas. According to the Town, groundwater pumping declined approximately 56 percent between 2005 and 2022, even as the community continued to grow.
CAP water did not end Oro Valley’s water challenges. It changed them.
The transition took two decades. During that time, Oro Valley created its Water Utility, acquired CAP rights, negotiated delivery through Tucson Water and invested in the infrastructure needed to reduce groundwater pumping and store water for the future. That planning gave the Town a more diverse and resilient supply, but it also tied Oro Valley’s water future to the Colorado River. The Town must now protect both its local aquifer and the distant reservoir system that supports its CAP water.
Between 2003 and 2008, Oro Valley invested $21.8 million in a two-phase reclaimed-water delivery system, financed through what was then the Town’s largest bond issue. The separate “pink pipe” network brought treated wastewater to golf courses, parks and school fields, replacing groundwater and drinking water previously used for irrigation.











