Raw sewage flowing under border tunnel from Mexico to Nogales
Untreated sewage and wastewater has been flowing intermittently from a tunnel originating in Nogales, Sonora, to the Nogales Wash, about a mile north of the U.S.-Mexico border, the Arizona Department of Environmental Quality said.
The tunnel where officials detected the untreated wastewater is meant to drain stormwater from Nogales, Sonora, which sits at a higher elevation than its sister city in Arizona, to the wash which empties into the Santa Cruz River.
"We're being told there's an issue with the wastewater treatment plant in Nogales, Sonora," Erin Jordan, ADEQ's spokewoman said. "We're still kind of confirming what the root cause is and how to move forward at this point and time."
Jordan said the flow has not been constant, and is "relatively low" when it is, estimated at about 10 gallons per minute. Nonetheless, the state agency is urging people to avoid the area.
ADEQ said they're in contact with the local utility companies, the Santa Cruz County Health Department, and the International Boundary and Water Commission, which is taking the lead to identify and solve the issue in Mexico. The binational organization is in charge of administering water issues that impact both sides of the border.
The IBWC notified ADEQ about the leak on Jan. 16, but when the city of Nogales checked it wasn’t flowing anymore. They determined it was intermittent.
Erin Jordan said the utility in Nogales, Sonora, is using chlorine to treat the area where the stormwater tunnel begins.
The IBWC has not responded to a request for comment. Its designated media spokesperson is on furlough because of the ongoing partial government shutdown.
This leak is the latest in a series of wastewater woes impacting communities along the Arizona-Sonora border. Because of the terrain, storm water, and occasionally wastewater and sewage, flows northbound into Arizona.
In July 2017, monsoon rains ruptured a pipe carrying untreated wastewater from Mexico to a binational treatment plant north of Nogales. Millions of gallons of raw sewage emptied into the Nogales Wash and the Santa Cruz River before the leak was fixed.
The small community of Naco, west of Douglas, has also been impacted regularly by sewage leaking from its sister city on the Mexican side.
The latest one happened in September 2018 when a conveyance line carrying untreated wastewater at the Naco, Sonora, treatment plant ruptured, releasing up to 60,000 gallons which flowed northbound into Arizona.