Long-delayed cross-border sewer pipe rehab completed in Nogales

Repairs to the International Outfall Interceptor — a vast wastewater line running beneath Nogales — were completed by a private contractor last month, officials announced Thursday.

For much of the last two decades, U.S. Rep. Raúl Grijalva and other congressional representatives have pushed to repair the faltering IOI, a 30-inch-wide sewer trunk line which carries 12-14
million gallons of raw sewage and runoff each day from Nogales, Sonora,
and Nogales, Ariz., to a treatment plant near Rio Rico. 

The IOI is part of an
international water treatment plan regulated by the International Boundary and Water Commission under a 1953

Because of the topology around Ambos or “Both” Nogales,
much of the flood water and sewage flows from the burgeoning city in
Mexico down to the Arizona side and in recent years, flooding in the
region has compromised the structural integrity of the IOI.

IBWC officials said the project was undertaken “because the pipeline reached the end of its useful life” and “long- standing structural integrity issues resulted in years of periodic releases of untreated sewage along the length of the IOI in the communities of Nogales and Rio Rico.”

“This project was first awarded for design 10 years ago, and USIBWC
is pleased to finally complete this critical rehabilitation after
overcoming various challenges, including agreements with stakeholders,
permitting, and cost-sharing,” officials said.

“This project
will reduce the risk of sewage spills historically experienced by
Nogales from collapsed portions of the IOI,” said Dr. Maria-Elena Giner,
IBWC’s commissioner in the U.S. “We would like to especially thank the
Arizona Department of Environmental Quality for their support and
assistance. Our gratitude is also extended to the City of Nogales and
Santa Cruz County, as well as to our funding partners, the Mexican
Section of the IBWC, the State of Arizona, and Freeport McMoRan

However, the project has been held up by a long-running fight over who should bear the cost of repairing the sewer line.

Grijalva garnered $10 million for a project to repair
infrastructure around the IOI, including the Nogales and Chula Vista
wash in 2009, and another $19.7 million in 2010 and 2011.

Meanwhile, flooding in 2017 undermined the IOI causing a leak near a
manhole and allowing untreated wastewater to bubble up into the
north-flowing Potrero Creek, which connects with the Santa Cruz River.

In 2018, Nogales residents worried the IOI could again rupture and become a major threat to the Santa Cruz River.

In June 2019, Grijalva introduced the Nogales Wastewater Fairness Act
with then-Sen. Martha McSally to make the IBWC responsible for repairs.
While the act was both bipartisan and bicameral, the bill never moved
forward in either the House or Senate. Grijalva later re-introduced the
bill with U.S. Sens. Kyrsten Sinema and Mark Kelly and then-Rep. Ann Kirkpatrick.

The IBWC said the project was broken down into five phases because of “funding constraints.”

Construction was hired for the project in July 2021 and
completed the first three phases in August 2023 at a cost of $13.8
million. Phases 4 and 5 were awarded to SAK in September 2022 as part of
a $15.3 million contract.

In April, SAK completed the
rehabilitation of the pipeline and manholes, the IBWC said, adding the
company still needs to restore landscape disturbed during

Grijalva praised the project’s completion.

“For 20 years, I have worked with the community of Nogales, my colleagues in Congress, and the federal government to end the failure and neglect of this pipeline,” Grijalva said in a statement. “Today’s news of the completion of the IOI pipeline rehabilitation is a historic and positive moment in this saga that will hopefully put an end to the persistent public health threat of sewage leaks.” 

“Moving forward, I will continue the work in Congress to ensure that the pipeline is fully funded to complete the transfer of ownership to the U.S. IBWC,” he said.

Nailing down who is responsible for the cost of the repairs has been its own headache. Officials in Nogales, Ariz. balked at the cost of repairing the IOI after the commission asked city officials to cover nearly a quarter of the cost. Nogales officials argued the sewage is a federal issue because 90 percent of the effluent comes from Mexico.

In 2019, the IBWC estimated it would cost around $27 million to repair one-third of the IOI and asked Nogales for a 23 percent “local match,” or about $6 million, Cronkite News reported.

The estimated cost comes from the 2004 settlement of a federal lawsuit, which required the city of Nogales to cover 23 percent of the cost of the treatment plant’s operating costs, estimated at $5 million until the city repaired or replaced the IOI, the Nogales International reported.

Last year, Sens. Kelly and Sinema added the Nogales Wastewater Improvement Act to the National Defense Authorization Act. As part of the must-pass defense bill, the legislation shifts ownership of the IOI to the IBWC. Grijalva introduced similar legislation in 2022 when he served as the chair of the House Natural Resource Committee.

The IBWC announced in April that Nogales agreed to transfer ownership of the IOI to the USIBWC, and the agreement will take effect once Congress approves another $12.5 million for operation and maintenance of the pipeline.

“In light of the particular international challenges involved with the IOI, and the $34 million federal investment in its rehabilitation, USIBWC is eager to take on responsibility for the pipeline’s maintenance,” said Giner last week. “Prioritizing preventive maintenance will help avoid pipeline breaks and leakage, ensuring more cost-effective repairs and letting us better fulfill our mission of treating U.S. and Mexican wastewater.”