San Luis Rio Colorado, Sonora, Mexico

Expansion of the wastewater collection system in Avenidas B in San Luis Rio Colorado, Sonora

Status: Completed


In 2000, OOMAPAS undertook a city-wide comprehensive water and wastewater infrastructure improvements plan to be carried out in several phases. The first phase, which consisted of improvements to the wastewater collection and conveyance systems and the construction of the first two treatment modules of the Las Palmas Wastewater Treatment Plant, was completed and began operations in the first half of 2007. The second phase, which consisted of increasing wastewater collection coverage and treatment capacity from 9 million to 13.7 million gallons a day (mgd), was completed at the end of 2010. A third phase to expand wastewater services to unserved areas south of the city was completed in 2013, providing access to wastewater collection services to approximately 85% of the city. As of 2013, approximately 63% of the wastewater generated by city was being collected and treated.

In order to further increase wastewater collection coverage OOMAPAS is proposing a project to extend sewer lines to alleyways known as “B Avenues” located within eight sectors of the city. Without access to the sewer system, residences in these areas use cesspools and latrines for wastewater disposal. Based on the design plans, the new sewer lines will collect and convey an estimated 1.07 mgd of wastewater flows to the treatment plant, which has sufficient capacity to treat the additional wastewater flows.


The proposed project consists of expanding the sewer system in eight sectors of the city and includes the following components:

  • Construction 253,179 linear feet of 8-inch PVC sewer lines,
    which will provide access for 4,369 residential sewer
    connections; and installation of up to 4,369 residential sewer hookups.


This project will provide first-time access to wastewater collection and treatment services to an estimated 16,122 residents and will increase wastewater collection coverage from 63% to 70% of the population. As a result, the project will eliminate a potential source of groundwater contamination from inadequate onsite disposal systems, thus reducing the
environmental and health risks associated with untreated sewage. Specifically, an estimated 1.07 mgd of wastewater will be collected and treated prior to being discharged.

Project Financing

Total Project Cost US 6.91M
NADBank Funding US 3.46M - NADBank Grant: BEIF
Other Funding Partners Border Environment Infrastructure Fund
Mexican Federal Water Commission, CONAGUA