Piedras Negras, Coahuila, Mexico

Comprehensive Sewerage Collection and Treatment Systems Project in Piedras Negras, Coahuila

Status: Completed


In the last few years population growth in Piedras Negras has surpassed the capacity of its environmental infrastructure, particularly in the areas of wastewater collection and treatment facilities. As of 2003, the sewer system provided service to only 87% of the population.

In addition, many of the areas of the city that do have sewer service are experiencing problems due to deterioration of the system from age and lack of maintenance. Moreover, because it is a combined system also used for storm drainage, during heavy rainstorms the system overflows onto the streets.


The Project is divided into three phases to be carried out over a 20-year period and is designed to offer sewerage coverage to the city’s entire population, which is currently estimated at 262,000 residents.

Phase I (1999-2004)
The first phase consists of the construction of a wastewater treatment plant financed by a private concessionaire under a Build-Operate-andTransfer contract (BOT), closure of the existing facilities, and construction of collectors, sewer lines, and pump stations.

Phase II (2003-2006):
This phase focuses on expansion of the primary and secondary wastewater collection system started in Phase I with emphasis on zones without service and consists of the construction and rehabilitation of more than 100 km. of pipelines to cover approximately 27,000
additional residents, as well as the installation of micrometers that will allow SIMAS to use volumetric rates for all its customers and thus reduce water consumption and wastewater discharges.

Phase III (2007-2018):
The last phase consists of expansion of the primary wastewater collection system to maintain 100% coverage and includes the construction of approximately 500 km. of sanitary sewer lines.


With the implementation of this project, all Piedras Negras residents will receive wastewater collection and treatment services. Moreover, expanding these services will help prevent raw wastewater discharges into the Rio Grande and Escondido Rivers, as well as into the San
Fernando and Tornillo streams, thus improving the overall health and well-being of current and future residents of Piedras Negras, Coahuila, and Eagle Pass, Texas.

Project Financing

Total Project Cost US 56.82M
NADBank Funding US 2.45M - NADBank Loan
US 8.4M - NADBank Grant: BEIF
Other Funding Partners Mexican National Water Commission (CONAGUA)
Mexican state and local funding