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Nogales Field Office and Wastewater Treatment Plant (NIWTP)

The Nogales International Wastewater Treatment Plant, (NIWTP) is adjacent and westerly of  the Santa Cruz River/Nogales Wash confluence, about ten miles north of Ambos, Nogales. It treats a daily average dry weather flow of approximately fifteen million gallons, of which approximately eighty per cent is from Mexico.

                  Nogales IWWTP

A technology upgrade of the NIWTP was completed in August of 2009. This upgrade consisted of adding equipment and apparatus to upgrade the technology of the NIWTP to a Biological Nutrient Removal (BNR) system using the Modified Ludzack-Ettinger process. This process allows for the removal of Nitrogen compounds in the discharged effluent which had been shown to be detrimental to the fish & wildlife along the Santa Cruz River. The technology upgrade cost approximately $64 million dollars and was funded largely by a grant from the Environmental Protection Agency (EPA) thru the Border Environment Infrastructure Fund (BEIF).

The project is staffed by seventeen persons, including administrative support and is Operated and Maintained by the United States Section of the International Boundary & Water Commission.  Total yearly operation and maintenance cost is about $4.5 million dollars. Mexico, the City of Nogales, Arizona, and the U. S. Congress fund the project based upon flow contributions to facility from each country. In addition to responding to federal and state permits, the NIWTP provides river-based habitat for approximately ten downstream miles as well as replenishment of the aquifers serving Santa Cruz and Pima County communities.

Nogales Stormwater Infrastructure Presentations

Modeling Storm Water at Ambos Nogales
Grand and Morely Tunnels in Ambos Nogales

Reports Concerning the NIWTP:

Nogales IWTP Pre-Treatment Analysis 2015

Wastewater Characterization Study, March 2015

Pre Treatment Analysis Through 3rd Qtr 2015

Agenda Nogales October 2015 Meeting

NIWTP AZPDES Annual Report 2014

NIWTP Report on Pretreatment Activities for 2006

Nogales International Wastewater Treatment Plant (NIWTP) information brochure

Final Report of the Binational Nogales Wash United States/Mexico Groundwater Monitoring Program dated August 2001

Joint Monitoring of the Quality of the Groundwater in the Ambos Nogales Area, Binational Nogales Wash United States/Mexico Groundwater Monitoring Program Interim Report of May 1998


Links to Other Field Offices

Amistad Dam Falcon | Las Cruces | Mercedes | Presidio |San Diego | Yuma |Zac Dominguez