In the Tucson AMA, groundwater is currently used at twice the rate it is replenished. Groundwater overdraft has lowered groundwater levels by as much as 200 feet (~60 meters), contributing to locally increasing subsidence and lowered well yields. The total volume of existing water rights and groundwater withdrawal permits currently exceeds natural and incidental recharge by a factor of 2.8. The AMA's management goal is to meet “safe-yield” by 2025. This will be a formidable challenge for high growth communities such as the Town of Oro Valley, Arizona (TOV), where the current management plan projects a demand approaching 17,000 acre-feet annually (AFA), and the current recharge estimate is approximately 2,500 AFA. Fortunately, TOV has alternatives available to augment its groundwater supply. These include rights to 2,294 AFA of Central Arizona Project (CAP) water, acquisition of additional CAP water rights, and direct purchase of surplus water from Tucson, and use or purchase of reclaimed wastewater. This paper addresses TOV's process of evaluating the feasibility of such alternatives.
Wet water v. paper water: water management under the 1980 Arizona groundwater code.
The Arizona Groundwater Management Code was enacted in 1980 to address the trend of widespread groundwater depletion across the State. The Code limits withdrawals of groundwater within designated areas (known as Active Management Areas or AMAs) to holders of groundwater rights, service area rights, groundwater withdrawal permits, and small domestic water users. Each AMA is required to maintain a management plan, which assures that new uses are consistent with specific goals. To date, 5 AMAs have been established. These are located within more arid, more populated central and southern portions of Arizona. Among the controls exercised in the management plans are strict limitations on groundwater withdrawals, prohibition of irrigation expansion, requirements for demonstrating an assured water supply upon petitioning for new subdivisions, and periodic measurement and reporting of usage. Additionally, AMAs must develop conservation requirements for each user sector.