The International Outfall Intercepter (IOI) is the conveyance mechanism between the Nogales, Sonora, wastewater collection system and the wastewater treatment plant in Rio Rico, Arizona, that treats waste from both Sonora and Arizona. Long-standing structural integrity issues associated with the IOI have resulted in years of periodic releases of untreated sewage along the length of the IOI in the communities of Nogales and Rio Rico.

On June 30, 2020, officials from ADEQ and the United States Section of the International Boundary and Water Commission announced a Settlement Agreement that addresses Clean Water Act (CWA) issues and sets forth a comprehensive plan to mitigate future discharges of untreated wastewater into the Nogales Wash and Santa Cruz River in Nogales, Arizona. With $38,790,000 in federal, state and local non-profit resources, the plan brings much-needed infrastructure improvements to Santa Cruz County.

The scope of the settlement includes:

• Upgrade the aged wastewater conveyance pipeline, commonly known as the IOI, from the U.S.-Mexico Border to the Nogales International Wastewater Treatment Plant (NIWTP) in Rio Rico, Arizona.
• Install protective measures for the upgraded IOI in locations vulnerable to damage from stormwater and debris.

ADEQ and USIBWC Achieve Landmark Settlement to Address Wastewater Impacts Press Release | View >

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