Tijuana River Valley Needs and Opportunities Assessment: Strategies to Improve Water Quality

Date / Time:
Wednesday, Sep 16 4:00pm to 4:30pm
Track / Session:
Track: Stormwater Infrastructure and Natural Waterways / Session 9

In February 2017, a large sewage spill occurred in Tijuana, Mexico that resulted in over 140 million gallons of wastewater entering the United States (U.S.) via the Tijuana River over several weeks. This spill reinvigorated local efforts in San Diego to address a longstanding issue of flows in the Tijuana River, which often contain sewage, crossing into the U.S. from Mexico. The sewage in the Tijuana River has been an issue dating back to the early 1980’s due to a population surge in Tijuana. In October 2017, Senate Bill 507, sponsored by Senator Ben Hueso, was enacted by the State of California. Senate Bill 507 provided grant funding to the County of San Diego to complete a comprehensive needs assessment to review and assess potential solutions to transboundary flows associated with the Tijuana River Valley.

The Tijuana River Valley Needs and Opportunities Assessment (NOA) Report provides a comprehensive review and assessment of current and potential management strategies that could be implemented on the U.S. side of the border to address transboundary flows of sewage, trash, and sediment into the Tijuana River Valley. The Tijuana River crosses from Mexico into the U.S. approximately five miles upstream of its outlet to the Pacific Ocean. While dry-weather flows from the Tijuana River are intended to be diverted to a treatment system in Tijuana, Mexico before reaching the U.S., the amount of flow that occurs during rain events generally exceeds the capacity of the diversion system in Tijuana. This limited diversion capacity results in frequent transboundary flows of sewage, trash, and sediment, which cause public health, environmental, and safety issues. As the transboundary flows reach the outlet into the Pacific Ocean, beach closures along our region’s beaches have been widespread.

The approach to NOA was developed in two stages. The goal of the first stage was to complete a comprehensive needs assessment to evaluate the current issues in the Tijuana River Valley and review past, current, and planned efforts intended to address the ongoing water quality issues. Over 600 documents were collected and reviewed to inform baseline conditions. These documents include draft and completed studies and reports, raw data, state and federal legislation, presentations, meeting minutes, questionnaires, brochures, articles, press releases, legal documents, and transcripts. The goal of the second stage was to identify and evaluate potential projects that can be implemented on the U.S. side of the border to address the cross border flows of sewage, trash, and sediment. The second stage also included development of an assessment document that details the projects that can be implemented. The intent of the final assessment is to demonstrate the magnitude of the issue and potential solutions so that entities across the region can work together to identify funding and other resources necessary to address the long-standing water quality issues in the Tijuana River Valley. The NOA Report identifies a total of 27 projects; 18 structural projects and nine non-structural projects, which are all intended to address the three main issues of concern considered in this study: water quality (sewage), trash, and sediment.

This presentation will highlight the actions taken following the 2017 sewage spill in Tijuana, Mexico that led to several months of beach closures along our region. Highlights include the public workshop held with the local community and coordination efforts with over 30 different stakeholders that represent the Tijuana River Valley Recovery Team. The presentation will demonstrate the project alternatives to capture up to 163 million gallons per day of dry and wet-weather flows from the Tijuana River Watershed for treatment prior to discharging to the Pacific Ocean via the South Bay Ocean Outfall.

Primary Speaker:
Alex Yescas, HDR, Inc.
Alex Yescas has 20 years of experience specializing in hydrology, hydraulics, scour analysis, stormwater improvements and flood control design. Alex is a professional engineer in California, a Certified Floodplain Manager, and an Envision Sustainability Professional. Alex is leading the water resources planning and design efforts for HDR that includes alternative delivery, to support Southern California agencies on implementing award winning stormwater facilities to meet stormwater compliance. Alex is the current Chair of the Floodplain Management Association which provides support to floodplain management agencies in California, Nevada, and Hawaii. Alex is on the San Diego APWA Water Resources Committee, San Diego IRWM Regional Advisory Committee, and Southern California Water Coalition Stormwater Task Force.
Supporting Speaker 1:
Deborah Mosley, County of San Diego
Deborah has been with the County of San Diego since 2007. She currently oversees a team of planners, biologists, and trails coordinator who provide environmental review, implement the County’s Multiple Species Conservation Program, plan and implement the County’s Trail Program, and acquire land for parks and open space purposes. Prior to joining the Department of Parks and Recreation in 2016, Deborah worked in the Watershed Protection Program of the Department of Public Works, where she focused efforts on water conservation and other sustainability projects.