Naco, Sonora, Mexico

Water Supply, Wastewater Collection and Treatment Project for Naco, Sonora

Status: Completed


The existing water supply system was unable to meet the needs of the urban area because of leaks and a failing pump system, which gave rise to chronic water pressure problems that adversely affected the quality of water services. In addition, the total absence of metering fostered inefficient water usage and billing practices.

The existing wastewater collection and treatment system was also insufficient as it only covered up to 85% of the urban area and only 65% of the population was connected to it. In addition, the treatment system did not have the capacity to hold all of the wastewater generated by the community.

The ponds operated as closed systems without discharges to a receiving stream, with the exception of small amounts of effluent used for irrigation. Since the amount of incoming sewage frequently exceeded evaporation and infiltration losses, severe overflows of partially treated wastewater often occurred. Due to the slope of the land, these overflows tended to runoff towards the international border line, flooding the wellfield that serves as a water supply for the city of Bisbee, Arizona. Recurrent failure of the pumping equipment due to wear and tear aggravated this situation.


The main components of the project include:

  • Upgrading the existing water supply wells and improving the
    water network.
  • Constructing a new Eastside collector.
  • Expanding the network of residential pipelines and outlets.
  • Upgrading and expanding the existing Eastside oxidation pond
    module and building a new pumping station to connect the
    existing ponds to the expansion units.
  • Updating the users registry and rate structure, as well as the
    management information systems.


Improvements to the wastewater treatment pond system and pumping stations have resolved the problem of transboundary sewage spills, thus protecting the local aquifer from contamination. Improvements in the water system have reduced water losses due to leaks and promoted a more efficient use of water, thus extending the useful life of the only
local water supply.

Project Financing

Total Project Cost US 2.07M
NADBank Funding US 0.15M - NADBank Loan
US 0.95M - NADBank Grant: BEIF
Other Funding Partners Border Environment Infrastructure Fund
Loan & Guaranty Program
Mexican National Water Agency
Comisón Nacional del Agua (CNA)
U.S Section of the International Boundary and Water Commission (IBWC)