San Luis Rio Colorado, Sonora, Mexico

Expansion and Improvements of the Water and Wastewater Systems in San Luis Rio Colorado, Sonora

Status: Pre-construction


In 2000, OOMAPAS undertook the first phase of its master plan to expand its wastewater collection system to the entire community and provide wastewater treatment. This phase, which consisted of improvements to the wastewater collection and conveyance systems and the construction of the first two treatment modules of the wastewater treatment plant, was completed and began operations in the first half of 2007. The treated effluent complies with Mexican effluent standards and is being used to recharge the aquifer. Under this phase, wastewater treatment services were provided to a total of 25,106 sewer connections. The proposed project is the second phase of the City’s master plan to continue expanding sewer coverage and increase treatment capacity. The area proposed for expansion currently relies on latrines, cesspools and open ditches for wastewater disposal. This phase is designed to extend wastewater collection and treatment services to 73% of the population. Once the new project is complete, the total number of connections is expected to reach 38,027.


The proposed project consists of the following components:

  • Three collectors, extending a total of 60,762 lineal meters;
  • A force main, extending 5,565 meters;
  • Electromechanical equipment for the South Pump Station, consisting of three pumps with capacity 6,498 GPM each, with two pumps operating on a regular basis and one pump as backup;
  • The third wastewater treatment module to increase treatment capacity from 400 to 600 liters per second (lps) or 9 million to 13.7 million gallons per day (mgd); and
  •  Infiltration lagoons with a 200 lps (4.56 mgd) capacity for final disposal of wastewater treatment plant effluent from the third module.


This project will allow OOMAPAS to extend wastewater collection services to 73% of the city, thus preventing groundwater and soil contamination, as well as health problems caused by untreated wastewater, including gastrointestinal and parasite-related diseases. In addition, OOMAPAS will be able to treat and dispose of all the collected wastewater in compliance with state and federal regulations.

Project Financing

Total Project Cost US 12.15M
NADB Funding US 10.06M - NADB Loan
Other Funding Partners Border Environment Infrastructure Fund (BEIF)