Turning a Compliance Challenge into Long-Term Operational Success

REGION 6

Project Summary

In October 2025, Desert Sky Mountain Water Cooperative (DSMWC) partnered with the Southwest Environmental Finance Center (SW EFC) project team to address health-risks posed by elevated arsenic levels. Maintaining arsenic concentrations below EPA’s Maximum Contaminant Level (MCL) of 10 parts per billion is critical for protecting public health and maintaining Safe Drinking Water Act compliance, as long-term exposure to elevated arsenic levels is associated with skin and circulatory effects and an increased risk of cancer. DSMWC initially anticipated that returning to compliance would require significant treatment system upgrades and associated costs, creating a substantial financial burden for the small system.  

Through a collaborative technical and organizational assessment, the project team determined that a combination of maintenance and equipment issues were limiting treatment system performance, including problems with chemical injection points, filter media, and control systems, and that targeted maintenance, rehabilitation, and operational improvements would return the system to compliance at a much lower cost than originally anticipated.  

After the assessment, DSMWC hired a new operator, and the project team worked closely with system staff to complete operation and maintenance (O&M) tasks, assess system hydraulics and controls, and develop and update standard operating procedures (SOPs) for arsenic treatment and routine operations. These interventions helped return the system to normal functionality and improve arsenic treatment. As of September 2026, the system is functioning as intended, and laboratory results indicate that DSMWC is on track to meet their compliance deadline for reducing arsenic levels below the MCL. (Note: Because arsenic compliance is based on a running annual average concentration based on quarterly sampling, it takes several quarters of compliant samples to meet this standard.) 

DSMWC is continuing to strengthen its operations and protect water quality for its customers through additional improvements. These efforts include implementing a new method for treating backwash water, installing a new settling tank, and improving communication between the system’s wells, filtering system control, and dosing pumps to support more reliable and autonomous operations. 

This work laid the foundation for long-term system functionality, regulatory compliance, and protects the public health of the citizens served by the cooperative at a significantly lower cost.