IBWC Awards $552 Million Wastewater Plant Contract

The construction project aims to mitigate two decades of sewage runoff from Mexico into the Tijuana River.

Updated on Oct. 16, 2026 in Construction

Isometric editorial illustration of a concrete sedimentation tank and industrial filtration machinery, representing a major wastewater infrastructure project. — The U.S. International Boundary and Water Commission has awarded a $552 million contract to expand wastewater treatment facilities in San Diego. AI Illustration. Upload story photo >

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The U.S. International Boundary and Water Commission has expanded its wastewater treatment contract in San Diego to $552 million. This primary treatment facility expansion is designed to address long-standing sewage flows that have impacted the region for twenty years.

Why it matters

This infrastructure upgrade is a critical step in curbing sewage contamination originating from Mexico that frequently affects San Diego neighborhoods. While the current contract focuses on primary treatment, further funding is needed to complete the necessary secondary expansion.

The $552 million primary treatment contract is part of a broader project estimated at $600 million. The current construction schedule spans 1,643 days, with secondary expansion requirements still pending the acquisition of additional funds.

The players

U.S. International Boundary and Water Commission

This binational agency is responsible for applying the boundary and water treaties between the United States and Mexico.

Morley Construction

This company is serving as a primary subcontractor for the wastewater plant expansion project.

Southern Contracting

This firm is working as a project subcontractor to assist with the electrical and facility upgrades.

Technical Systems Incorporated

This entity is a project subcontractor providing specialized technical support for the construction.

The details

The current expansion includes building a new integrated headworks, a chemical system, two primary sedimentation tanks, and a sludge storage system. Workers will also install a new 12-kV electrical building with updated transformers, while the eventual secondary phase will require ten additional sedimentation tanks and seven activated sludge tanks.

Sewage flows from Mexico into the Tijuana River began or persisted starting in 2006.
The Stantec and PCL team secured the initial expansion contract in 2025.
Shoring, dewatering, and excavation activities begin in October 2026.
Substantial completion of the primary treatment facilities is slated for May 2031.

Market Landscape

This project represents a significant mobilization of public infrastructure capital to address long-standing transboundary environmental failures. It positions the U.S. IBWC alongside major engineering firms to tackle a complex regional crisis that has defied simple remediation for decades.

Residents in the Tijuana River area may see increased construction activity and equipment around the plant site in the coming months. While this phase focuses on primary treatment, the expansion is intended to improve long-term water quality in local communities like Imperial Beach.

The takeaway

This project marks a significant effort to resolve chronic environmental pollution through large-scale civil engineering. Local residents should monitor project milestones to stay informed about the timeline for potential water quality improvements in the Tijuana River watershed.

What happens next

Shoring, dewatering, and excavation work are scheduled to begin in October 2026, followed by a multi-year construction process leading to a projected completion date in May 2031.