"Conserving and sustaining all water resources...it's our future."
Santa Cruz AMA Goal
The management goal of the Santa Cruz AMA is to maintain a safe-yield condition in the active management area and to prevent local water tables from experiencing long term declines.
The Santa Cruz Active Management Area (AMA) covers 716 square miles in the Upper Santa Cruz Valley River Basin. It is principally concentrated around a 45 mile reach of the Santa Cruz River from the international border to the Continental gaging station, a few miles north of the Santa Cruz/Pima County line. Along this reach, the river is characterized as an intermittent desert stream that contains uninterrupted perennial and effluent dominated reaches. The drainage area of the Santa Cruz River upstream from Continental is about 1,680 square miles. From its headwaters in the San Rafael Valley, the river flows southward approximately 9 miles and enters Mexico. During its 35 mile course through Mexico, the river continues its southward flow for a short distance and then bends northward and enters Arizona 5 miles east of Nogales. Within the United States, the Santa Cruz River continues northward for 65 miles from Nogales to Tucson, where it continues beyond to the confluence of the Gila River. (Chapter II TMP for overview of AMA water resources.)
Analysis of Historic Water Level Data Related to Proposed Assured Water Supply Physical Availability Criteria for the Santa Cruz Active Management Area Santa Cruz and Pima County, Arizona – Modeling Report No. 18. - Proposed new groundwater withdrawals for Assured Water Supply (AWS) purposes in the Santa Cruz AMA must be consistent with the AMA’s dual water management goals of maintaining safe-yield and preventing local water tables from experiencing long-term declines (A.R.S. 45.562.C).
Santa Cruz AMA Groundwater Flow Model - Modeling Report No. 14 - The Arizona Department of Water Resources has developed a regional groundwater flow model of the Santa Cruz Active Management Area that covers a reach of the effluent-dominated Santa Cruz River in southern Arizona.
Santa Cruz AMA Groundwater Flow Model – Modeling Report No. 15 -The Arizona Department of Water Resources has developed a regional groundwater flow model of the Santa Cruz Active Management Area that covers the “Microbasin” reach of the Santa Cruz River in southern Arizona from the International Boundary to the Nogales International Wastewater Treatment Plant.
AMA Water Budget
AMA Conservation Requirements
The primary goal of the Santa Cruz AMA Conservation Program is to gradually reduce water consumption by encouraging the use of the best available water conservation practices and maximizing the efficient use of all water supplies including the direct use of effluent. In the Santa Cruz AMA, water conservation requirements apply to all water withdrawn from wells, other than stored water, regardless of the source. This is one way to ensure the efficient use of the water supply. The Department encourages the equitable distribution of water in an environmentally and economically sound manner through long-range planning, cooperative regional efforts, technical assistance, public education, and regulatory programs. The Department acknowledges that all of the statutory tools necessary to ensure effective water management in the Santa Cruz AMA may not be currently available, given the AMA’s unique goal and drought-sensitive water supply.
Santa Cruz AMA Major Water Management Challenges
New and innovative management tools for quantification and clarification of water rights and new sources of supply will need to be developed to achieve the AMA goals.
To meet the AMA goals, new uses of water within certain areas of the Santa Cruz AMA will need to be offset either by replenishment of water withdrawn or through a corresponding reduction in water use by existing users. Replenishment could be achieved through a mechanism to purchase recharge credits or in some circumstances by a demonstration that water pumped out of storage will be naturally recharged. Reduction in existing use could be achieved by discontinuing existing water use in the same local areas in which a new demand begins. Water that is conserved through increased efficiency could, in part, be taken up by a new use.
Coordinated Management of Surface and Groundwater
The Legislature has mandated that management of groundwater and surface water rights be coordinated in order to achieve the AMA goals. This will likely result in a high degree of water management awareness by the local water right holders in the Santa Cruz AMA. To successfully manage water supplies for the Santa Cruz AMA, groundwater programs cannot be implemented without examining the consequences to surface water rights. Surface water rights cannot be obtained or altered without examining the consequences to groundwater programs and overall water management efforts and the public interest.
Although the laws governing surface water and groundwater are distinct, they are not necessarily at cross-purposes. An effective coordinated management of surface and groundwater must provide the mechanisms to protect the water rights held under both legal authorities.
International Water Issues
The international nature of the Santa Cruz AMA water resources requires binational coordination of water management efforts. The Santa Cruz River is one of the main water supply sources for Nogales, Sonora and for Nogales, Arizona. The water management policies of Nogales, Sonora, in regard to the use of the Santa Cruz River, may have a direct impact on the volume of water entering the Santa Cruz AMA. Additional pumping of Nogales, Sonora Santa Cruz River well fields could reduce both small flood flows and sub-flow, thereby reducing the recharge in the Santa Cruz AMA.
The City of Nogales and Rio Rico are the two biggest water users in the municipal sector. They have been growing at the rate of 5 to 8 percent per year for the last 10 years. If this rate of growth continues creative water management policies will be required to maintain the AMA goals and meet the new water needs.
Greater development pressure may be coming from the north. Expansion of existing development in the Green Valley area is headed south. This development is already at the northern boundary of the Santa Cruz AMA and is expected to continue.
Development of Technical Data and Tools
The Department continues to devote considerable resources to the development of the groundwater flow model for the AMA. Due to its complicated nature, a considerable amount of detail is necessary to accurately simulate the hydrologic system. This work will help in conceptually understanding some of the relationships between the Younger and the Older Alluvium.
A major effort is in progress to establish assured water supply criteria for evaluating the statutory requirement that issuance of an assured water supply must be consistent with AMA goals. In order to develop the appropriate criteria, it is necessary to have a better understanding of: (1) the impact of diversions at specific locations of the subflow water levels; (2) the impact of the effluent introduced into the system and its long-term availability; (3) how effluent, surface water flows, and mountain front recharge affect Younger Alluvium water levels; and (4) a formal determination of nature, validity, and priority of surface water rights in the context of their usage in supporting an assured water supply determination.
The Department is in the process of drafting rule criteria for the AMA. Final adoption of these rules will reflect community and stakeholder input to the highest degree possible.
The hydrogeologic characteristics of the aquifers in the Santa Cruz AMA and their close relationship with surface water flow presents a challenge to augmentation and recharge that needs to be addressed with innovative approaches. Effluent discharge from the NIWWTP is a major source of recharge in the AMA, and it is a significant source of water available to support future assured water supply determinations. Additionally, the effluent plays a major role in maintaining water tables and riparian habitat in the Younger Alluvium downstream of the NIWWTP.
Management Plan Development and Modification
Transcripts of Public Hearings, Summary of Hearings and Findings, Orders of Adoption and Modification Language – On January 9, 2008, the Director issued orders promulgating proposed modifications to the Third Management Plans for the purpose of adding a modified Non-Per Capita Conservation Program. Public hearings on the proposed modifications were held in Phoenix, Casa Grande, Prescott, Nogales and Tucson during the first week of March, 2008. On April 1, 2008, the Director issued a summary of the hearings and findings with respect to the matters considered during the hearings (“Summary of Hearings and Findings”). In the Summary of Hearings and Findings, the Director indicated that two changes would be made to the proposed modifications in response to comments received during the public hearings. On April 1, 2008, the Director issued orders adopting the proposed modifications with the changes described in the Summary of Hearings and Findings.
Santa Cruz AMA Links
Santa Cruz AMA virtual tour - (4.4 MB) PowerPoint 97® (This file may take several minutes to download.)
Santa Cruz AMA Water Facts
Well Information Links
How to obtain well information (Link coming soon.)
Wells-55-Search for Wells (Link coming soon.)
Surface Water Adjudication
Arizona Department of Water Resources - 3550 N. Central Avenue, 2nd Floor, Phoenix, AZ 85012
Images around Santa Cruz AMA
Click on the images below for a large view.