Water Quality Alert | ADEQ continues to caution against contact with water in Nogales Wash due to intermittent sanitary sewer overflows from Nogales, Sonora

PHOENIX (October 8, 2019) — The Arizona Department of Environmental Quality (ADEQ) continues to caution against contact with water in the Nogales Wash and Potrero Creek due to an on-going potential for intermittent sanitary sewer overflows (SSOs) in a tunnel under the international border. This tunnel was built to transport stormwater from Nogales, Sonora to the Santa Cruz River.

In January 2019, ADEQ notified the public of the SSO potential, due to pump failures at the wastewater treatment plant in Nogales, Sonora. While the pumps have been repaired or replaced, an issue with electrical connections continues to be addressed. The U.S. and Mexico sections of the International Boundary and Water Commission (IBWC) are in contact with the utility in Nogales, Sonora, which is working to resolve factors contributing to the intermittent SSOs. ADEQ continues to monitor the situation and is also in contact with IBWC, the utility in Nogales, Sonora, the City of Nogales, Arizona and the Santa Cruz County Health Department.

During storm runoff, water levels may be higher than normal in local washes. Normally, there is persistent low flow in the Nogales Wash from a natural spring, plus water runoff and discharge originating in Nogales, Sonora. This water is not due to an SSO, but an SSO can mix with this water.

ADEQ urges people to avoid access to local washes in this area. This recommendation is based on potential health risks to people and animals from contact with raw sewage associated with the SSO. Untreated sewage carries pathogens that pose a risk to human health and the environment. People and animals that come into contact with untreated sewage are at risk of infection from those pathogens. Depending on volume of flow and frequency, an SSO could threaten the Santa Cruz River.

Recommended Actions:

  • Avoid contact with the water in this area, including wading, drinking and washing. If you have contact with the water, rinse using soap and clean water immediately.
  • Take care that pets and livestock do not drink potentially affected water. Pets can be especially susceptible because they tend to drink while in the water and lick their fur after exposure. Rinse pets using soap and clean water.
  • If you think that your health or that of your pet or livestock has been affected from exposure to raw sewage, seek medical treatment immediately. Be sure to tell the medical professional about contact with the SSO. Also, make sure to advise your local county public health department about the exposure details.

For more information, visit the resources below:

  • Arizona Department of Environmental Quality (ADEQ) Water Quality Division | View >
  • Report an Environmental Complaint to ADEQ | View >
  • U.S. EPA Sanitary Sewer Overflows | View >
  • International Boundary and Water Commission | View >
  • Santa Cruz County Health Services Agency | View >