Untreated wastewater is pouring into the Nogales Wash after city employees found a partial breach of an eroding pipeline that carries more than 10 million gallons of raw sewage per day from Nogales, Sonora, to Arizona.
During a Tuesday inspection workers found that a dislodged section of cement that encases one of the manhole accesses to the International Outfall Interceptor (IOI), partially sheared the pipe below the waterline, about 200 yards north of the intersection of Old Tucson Road and the Nogales Wash.
Santa Cruz County Health Services is advising people who live in areas where there is water running in the wash and tributaries east of the Nogales Wash to keep out of those areas. The Santa Cruz County Emergency Operation Center has been partially activated to support the efforts of local authorities, officials said in a news release.
Nogales City Manager Carlos Rivera said they don’t know yet how extensive the break is, but they can see sewage bubbling out and estimate fixing the problem will cost between $1 million and $2 million.
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 its thickness has eroded.
When it rains, groundwater infiltrates the pipe and increases the volume in the wastewater system.
IOI has 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 in 2012 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," Henry Darwin, director of the department said in 2013. "So if the IOI breaks, the water can be contaminated with chemicals too."
A hotline has been established for public and media inquiries at 520-375- 7784.
Updates will also be posted on the County Facebook page, Santa Cruz County, Arizona and Twitter page.