Metro Water District :: Groundwater Levels

Metropolitan Domestic Water Improvement District - Tucson, Arizona USA

Groundwater Levels

Water Level Changes in District Wellfield Areas (Spring 2000)

Responding to two consecutive dry winters, Metro Water District, which began preparing for its future water demands 6 years ago by embarking on the Tucson area's first Central Arizona Project recharge project and a $23 million capital improvement program, will step up its use of CAP water.

"The importance of bringing a renewable water supply to Metro Water has increased with recent evidence that our water levels are dropping at a faster rate than in the past few years," said Pete Schlegel, Chair of Metro Water's Board of Directors. "It is a challenge, but our past planning and efforts puts us in a good position to take on the task."

Metro Water measures the level of groundwater in its wells annually. The recent measurements showed that 15% of its wells have declined slightly more than five feet since last year. The decline has occurred in Metro's wellfields in the Cañada del Oro (CDO) basin as well as along the Rillito.

"Previously we had seen three-foot drops for some wells. We were surprised by the five-foot decline, which shows that we need to accelerate our efforts to utilize renewable water," said Mark Stratton, Metro Water's General Manager.

Metro Water has been pursuing the concept of constructing a pipeline from the CAP canal to recharge CAP water in the CDO Wash as well as the potential treatment of CAP water. Metro and the Towns of Marana and Oro Valley have explored the technical and financial aspects of a CDO Recharge & Recovery Project.

"We will be taking a closer look at the various options available to bring CAP water to Metro's well fields," said Schlegel. "It will not happen overnight or even in a couple of years, but we must start now to move aggressively lessen our dependence on the existing groundwater supply. We'll be certain that our whole approach is done right."

Metro's recharge feasibility studies along with other regional recharge studies have been positive to date.

The lack of substantial natural recharge is the main factor for the decline in groundwater levels. "People forget that our water originates in the Catalina Mountains. Without significant replenishment from winter precipitation, the groundwater level declines," said Stratton. The past two dry winters have substantially limited natural recharge and weather projections do not forecast the needed moisture for the foreseeable future.

Another contributing factor is the increased use of groundwater in the Catalina/SaddleBrook and Oro Valley areas. This means less water moves down the watershed to Metro Water's wells in the Lower CDO area. The same situation has occurred along the Rillito with continual pumping in Tucson's central well field slowing the usual western flow of the Rillito. Therefore, there's an overall decline in both areas.

"The decline in water level does not mean we're going to experience an immediate shortage of water. We will be able to meet demands for the near future," said Stratton. "What it does mean is that along with the rest of Southern Arizona, we need to recharge CAP water closer to our own wells."

"Metro's Board and staff have always tried to be proactive in addressing our current and future water resource needs," said Stratton. "This is why we obtained a renewable supply of water, 2.88 billion gallons annually of CAP water, and completed the first CAP recharge project using spreading basins in Pima County. Metro has also been conducting a lengthy analysis of recharging along the CDO Wash. This is also why we have embarked on a comprehensive Capital Improvement Program to ensure our water system meets our current and future needs."

Metro Water will continue its water conservation program, especially in reminding people of the importance of individual efforts to use water efficiently in the desert. "Metro Water has been a leader in water conservation and I have no doubt that they will continue with that role," said Val Little, Manager of the Water Conservation Alliance of Southern Arizona.

"We still strongly encourage our customers to use water wisely; however, conservation alone is not going to solve this problem," said Stratton. " The decline in water levels clearly shows that significant replenishment of our groundwater needs to take place."