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San Luis Rio Colorado, Sonora, Mexico
Expansion of Wastewater Collection and Treatment Systems
On this page:
- Project Location and Description
- Purpose and Need for the Proposed Action
- Environmental Assessment and Finding of No Significant Assessment
- Contact Information
Project Location and Description
EPA is considering authorizing the award of a Border Environment Infrastructure Fund (BEIF) grant to the City of San Luis Rio Colorado, for construction of wastewater collection lines and expansion of the community's wastewater treatment plant to serve existing residents that lack adequate wastewater treatment and disposal. San Luis Rio Colorado, a municipality comprised of more than 150,000 people, is located in the northwestern part of the State of Sonora, Mexico, on the U.S./Mexico border, adjacent to the town of San Luis, Arizona.
Purpose and Need for the Proposed Action
The purpose of the proposed action is to address the environmental and public health risks associated with inadequate collection, treatment and disposal of wastewater. The proposed action will protect public health by providing appropriate wastewater collection and treatment to approximately 45 thousand residents that now rely on cesspools or open ditches for wastewater disposal. The proposed action consists of the installation of approximately 65 thousand linear meters of laterals and subcollectors, a lift station and force main with a capacity of 410 lps and a 200 lps (4.6 MGD) expansion of the wastewater treatment plant. The expansion of services will result in the collection and treatment of around 140 lps (3.2 MGD) of raw wastewater that would otherwise be discharged untreated to the environment. The wastewater treatment plant expansion will consist of the addition of a third lagoon system module to the facility. The treatment plant's effluent will be directed to infiltration basins for aquifer recharge instead of the current process, which discharges to a local irrigation canal. The proposed action will significantly reduce the use of inadequate wastewater disposal practices in San Luis Rio Colorado by expanding collection, conveyance and treatment services from 49% to 73% of the community, resulting in improved environmental and sanitation conditions.
EPA's involvement in the San Luis Rio Colorado, Sonora project is part of a national commitment to improve environmental conditions along the U.S.-Mexico border. EPA participates in the development and implementation of water supply and wastewater infrastructure projects in coordination with the Border Environment Cooperation Commission (BECC) 
and the North American Development Bank (NADBank) . BECC is responsible for certifying projects so that they comply with sound technical, environmental, financial, and public participation principles. NADBank administers the BEIF grants for projects that have been certified by BECC and approved by EPA.
Environmental Assessment and Finding of No Significant Impact
In compliance with the National Environmental Policy Act (NEPA), EPA has prepared a Supplemental Environmental Assessment (SEA) that supplements the Environmental Assessment of the Effect on San Luis, Arizona by the Proposed Construction of a Wastewater Treatment Plant and Improvements to the Wastewater Collection System for San Luis Rio Colorado (EA), which was prepared by EPA in January, 2000. The purpose and scope of the SEA is limited to cataloging the changes that have been made in the project's design since the original assessment was written and detailing the potential impacts that may occur as a result of those changes. After considering a wide range of regulatory, environmental (both natural and human) and socio-economic factors, the SEA did not identify any significant impacts to the environment that would result from the implementation of the modified wastewater collection system and treatment plant improvements.
The EA and Finding of No Significant Impact (FNSI) are being made available for public review for a 30-day comment period that ends on June 3, 2007. Interested persons, including those who disagree with this proposal, may submit written comments to EPA Region 9.
To view the EA or FNSI, please click on the links below.
- Environmental Assessment (PDF) (60 pp, 1.4M, About PDF)
- Finding of No Significant Impact (PDF) (2 pp, 37K, About PDF)
Contact Information
For further information about these documents, contact:
Thomas Konner (konner.thomas@epa.gov)
U.S. EPA Region 9 (WTR-4)
75 Hawthorne Street
San Francisco, CA 94105
Phone: (415) 972-3408
Fax: (415) 947-3537