Water Resources Portfolio

The District has long understood the importance of effectively and efficiently managing its water resources. The District’s Long Range Water Resources Plan for each of the District’s six active service areas gives a snapshot of the District’s projected water demands compared to available renewable supplies (Central Arizona Project (CAP) water, effluent, and remediated water) and groundwater availability and outlines the District’s strategy to manage water resources for the next 50 years.

Groundwater – Groundwater is the current sole source of water for District customers. Metro Main has 26 active wells that pump water from the aquifer underneath the Cañada del Oro Wash and Rillito River. Water from the wells is placed in storage tanks or reservoirs. The water is then pressurized to move underground through pipes to reach customers. The Metro Hub service area has 5 wells that pump water beneath the ground along Sabino Canyon Creek and Tanque Verde Wash. The Metro Southwest service areas have 5 wells that pump groundwater that originates from mountain front recharge and minor streamflow along the Black Wash. 

Other Water Sources – Based on the Arizona Groundwater Management Code and the assured water supply designations for Metro Main and Metro Southwest – Diablo Village, the District has sought to use a renewable water source to reduce its dependency upon groundwater in these service areas. Other water sources, including CAP water and recycled water, are considered renewable water sources. These other water sources can help stabilize the aquifer and reduce the use of groundwater.

Central Arizona Project (CAP) Water – The District has an annual allocation of 13,460 acre-feet (approximately 4.4 billion gallons) of CAP water. The District has primarily looked at replenishing CAP water by pursuing projects in which the water is recharged by spreading basins (direct recharge projects) and in which CAP water is used in lieu of groundwater by farms (groundwater savings projects or GSF). In fact, the District helped initiate the Northwest Replenishment Program, an effort to recharge CAP water in northwest metropolitan Tucson. The Avra Valley Recharge Project (AVRP), was the first recharge project using spreading basins in Pima County and was done in partnership with CAP and BKW Farms.
From 1996 to 2021, the District has stored 200,690 acre-feet of water at AVRP through its CAP water recharge efforts. While the District uses credits on an annual basis to meet a portion of customer demand, the District’s long-term storage credit account is 48,482.58 acre-feet as of December 31, 2021
Over the years, the District has pursued how to bring CAP water to the various service areas. The District has partnered with the Town of Marana and the Town of Oro Valley to design and construct the Northwest Recharge, Recovery, and Delivery System (NWRRDS) that will recover a portion of the respective water provider’s CAP allocation stored in AVRP and provide a means to convey this water to the Marana Water, Oro Valley Water, and Metro Main service areas. This will reduce the amount of groundwater that is pumped to meet customer demands, reduce the ongoing decline in groundwater levels in the aquifer, and will ensure water resource availability for current and future customers. 

Effluent or Recycled Water – The District has an entitlement to approximately 4,000 acre-feet of effluent generated from the Metro Main and Metro Hub service areas based on an Intergovernmental Agreement (IGA) with the City of Tucson.  The District has worked with other regional water providers to establish a joint managed effluent recharge project in the Santa Cruz River that allows the District to obtain 95% credit for the effluent recharged, which could range from 450 to 950 credits annually after the cuts associated with the managed in-channel recharge facility are taken into account.
Another use for the District’s effluent allocation is to utilize reclaimed water through a wheeling agreement with Tucson Water to replace groundwater irrigation for large turf facilities in the District. This would require utilizing a reclaimed system and the construction of a delivery system to move the reclaimed water where it may be needed. The District constructed a reclamation line that can deliver approximately 250 acre-feet of reclaimed water to the Omni Tucson National’s new nine golf holes and replace groundwater irrigation to that facility starting by December of 2023. The use of reclaimed water will help to reduce the decline of the groundwater table.

Water Usage – Metro Main customers used 6,993 acre-feet (2.3 billion gallons) of water in 2021. While all the water was pumped from wells, most of it was calculated as recovered CAP water based on the credits the District accrued through its recharge efforts. Metro Hub customers used 811 acre-feet (264 million gallons) of water in 2021. Metro Southwest customers used 525 acre-feet (171 million gallons) of water in 2021. Wheeling agreements with Tucson Water at Diablo Village and Lazy B enable the District to meet a portion of customer demand with renewable water resources.

Avra Valley Recharge Project (AVRP) and Recharge CAP Allocation – In 2010, the District Board approved the use of recharge as the initial treatment method for its CAP water allocation and the District acquired AVRP in 2011. Recharge was seen as a less expensive alternative with lower capital but still as effective as a treatment plant. The CAP water delivered to recharge facilities accrue credits that are partially used each year as annual storage and recovery to offset groundwater pumping. The remainder of the credits is stored as long-term storage credits for future use. 

Northwest Recharge, Recovery & Delivery System (NWRRDS) – This Project will use wells to recover CAP water that has been recharged in AVRP. In partnership with the Town of Marana and the Town of Oro Valley, this Project will allow for the District’s CAP water allocation to be delivered within its Metro Main service area. This is accomplished by recovering CAP water in the vicinity of AVRP and then delivering it through a 13-mile transmission main line to be blended with groundwater at the Herb Johnson Reservoir.
With the importation of CAP water into the Herb Johnson Reservoir, an equal volume of water will no longer need to be pumped from Metro Main production wells. It is expected that this will result in the cessation of groundwater declines seen over the past several decades. There is also the possibility of groundwater level recovery in some areas due to the reduction in pumpage in the Metro Main service area.

Drought Contingency Plan (DCP) – In 2019, the Drought Contingency Plan (DCP) was signed by all of the seven Colorado River Basin States and outlined levels of shortage to be borne by the Lower Basin States based on water elevations in Lake Mead. The reductions in Arizona’s allocation will only affect CAP water supplies available to central Arizona water users. To make up for the needed reductions in CAP supplies necessary to meet DCP reductions, CAP entered into compensated system conservation programs. The District proposed a Compensated System Conservation (CSC) agreement with CAP in 2019 and was the first M&I subcontractor to enter into such an agreement with CAP.

The District has been providing 3,500 AF of its allocation for the CSC since 2020. The remaining 9,960 AF of the District’s CAP allocation has been requested to be delivered to GSFs, on an annual basis since 2020, to mitigate Pima County agriculture firming needs. This has resulted in 100% of the District’s CAP allocation supporting the DCP while also benefiting District customers.

In 2021, the BOR and the Lower Colorado River Basin States (Arizona, California, and Nevada) determined that an additional 500,000 AF of water was needed to stay in Lake Mead starting in 2022. The 500 Plus Plan was developed to provide this water with additional compensation to water users that contributed to the needed water savings. The District’s 3,500 AF was added to the 500,000 AF and will continue at least through 2023.