A bypass is necessary to capture sewage in the Nogales Wash to facilitate repairs at the border with Mexico


An eroding pipeline that carries more than 10 million gallons of raw sewage per day from Nogales, Sonora, to Arizona is a catastrophe waiting to happen especially as the monsoon season approaches, officials said.

If the International Outfall Interceptor, or IOI, fails, raw sewage and heavy metals in industrial wastewater could end up in the Santa Cruz River.

The problem is so dire, Arizona Sens. John McCain and Jeff Flake gave the State Department until Wednesday to respond to their latest letter seeking a solution.

"Severe flooding over the past few years, as well as the high volume of sewage coming from Mexico and blockages caused by drug smugglers have damaged the Nogales Wash and compromised the integrity of the IOI," the letter reads.

"It has been nearly a year since the State Department promised a 'fuller response' that would address the ongoing cost-share issue," Flake said. "Without that clarification, taxpayers in Nogales face the prospect of a significant public health threat. Senator McCain and I believe an answer is long overdue."

The IOI carries wastewater nearly nine miles from Sonora to a treatment plant in Rio Rico.

The 42-year-old pipeline runs about three feet below the bottom of the Nogales Wash and over time has developed cracks and half of the thickness has eroded.

When it rains, groundwater infiltrates the pipe and increases the volume in the wastewater system, said Nogales Mayor Arturo Garino.

"During monsoon, water that flows from Mexico can exceed 17 million gallons a day," he said. "It puts way too much pressure. We would need a line twice as big."

The question is who pays for it?

The International Boundary and Water Commission has said the cost should be split 50/50 with the city of Nogales.

The commission is a binational agency which governs cross-border issues between Mexico and the United States.

"We are trying to get IBWC to take care of (the IOI) but they say it's ours," said Garino, who disagrees because "the majority of the flow comes from Mexico."

Sally Spener, spokeswoman for the U.S. section of the IBWC, said the commission is consulting with the U.S. Department of State regarding the appropriate cost share for work on the pipe.

"We are exploring all legal options regarding emergency repairs and long-term design and rehabilitation of the IOI," she said.

A couple of years ago, the estimated cost to rehabilitate the pipe was about $30 million, Garino said, "there's no way the city can afford $15 million to improve the line."

The emergency repairs for this year include encasing about 30 feet of the exposed pipe with concrete and re-establishing the bed and bank of the Nogales wash, said Spener. An estimated cost for the project was not available.

IOI had major failures every year from 2007 until 2011, some of which impacted the Santa Cruz River, according to the Arizona Department of Environmental Quality, which sued the commission last year for allowing untreated Industrial wastewater to cross the border at Nogales.

"The wastewater that originates in Mexico is also industrial which is difficult, if not impossible to treat," said Henry Darwin, director of the department. "So if the IOI breaks, the water can be contaminated with chemicals too."

On StarNet: Read the letter to the State Department by Senators McCain and Flake at azstarnet.com/pdf


• In 2007, after high flows in Nogales Wash dislodged concrete panels and exposed part of the IOI to stormwater flows, emergency repairs were undertaken to the Nogales Wash.

• On July 6, 2008, Nogales officials declared a state of emergency after heavy monsoon rain tore up several concrete floor panels in a 200-foot section of the Nogales Wash about 1 1/2 miles north of the border exposing the IOI.

• That year, IBWC used $500,000 Congress appropriated to repair part of the wash to protect the IOI.

• March 2009 Marijuana bundles found in IOI.

• In October 2010, a part of the IOI developed a leak near the international boundary. IBWC spent $1.4 million on the emergency repairs.

Source: Archives, IBWC

Contact reporter Perla Trevizo at ptrevizo@azstarnet.com or at 573-4213. On Twitter: @Perla_Trevizo