The latest United States-Mexico-Canada Agreement (USMCA) Tijuana River Watershed Public Information meeting on Nov. 8 presented a new comprehensive infrastructure solution for the sewage problem coming from the border. This alternative compared to the other presented in the past reduces the transboundary flows by 76 percent and 95 percent reduction on water quality impacted in Imperial Beach during high season. The new solution called Alternative I-2 would expand the capacity of the International Treatment Plant (ITP) to 35MGD from the current 25, for a total of 60MGD. The pumps in the canyons in Mexico would be decommissioned and the sewage allowed to flow by gravity to the ITP. The expansion of the ITP would allow to handle the growth of the Tijuana population up to 2050.
This alternative has the potential to use the treated effluent from ITP in Mexico. While at last meeting the plan proposed a 10 MGD wastewater treatment plant at San Antonio de Los Buenos this new project downsizes it to 5 MGD. The two treatment plants in Mexico that currently discharge 10 MGD of treated effluent into the river, which gets mixed in with river water, and contributes to dry weather flows will be redirected to PB CILA. This project proposes sending treated effluent to the Rodriguez Reservoir rather than being discharged into the river. The collector’s repair project has 10 MGD sewage flowing into it. This flow would be reduced to half through the collector’s repair project. This alternative also proposed river diversion on the U.S. side to supplement a diversion system that already exists in Mexico. Currently the flows are pumped to the coast after treatment. In this alternative the existing water diversion in Mexico would send dry river flows up to 35 MGD to a new advanced primary treatment plant to treat up to 60 MGD. Trash booms would be installed in the river that would keep the transboundary trash contamination from reaching the estuary. This alternative compared to the others presented in the past reduces the transboundary flows by 76 percent and 95 percent reduction on water quality impacted in Imperial Beach during high season. The potential sequence of the project is envisioned in stages: expand the ITP, covey canyon flows to ITP, build U.S. side advanced primary treatment plant and lastly build the U.S. side river diversion.
The Environmental Protection Agency (EPA) has engaged with Mexico specifically with meetings held with the U.S. Ambassador to Mexico, the consul general as well as other agencies and Baja state government officials. The EPA, CONAGUA, International Boundary Water Commission (IBWC) and others have meet twice a week with the goal to reach an agreement on projects to be built, discuss cost sharing and memorialize an agreement.
For the project to be implemented a congressional authorization is needed to transfer funds to the IBWC not only for construction but operational and maintenance for the new systems.
The key benefits, which this alternative provides, is U.S. oversight and control of wastewater infrastructure, sufficient capacity for all dry weather and some wet weather flows, act as a backup if Mexico’s diversion fails or flows exceed capacity. Another benefit is that the increased capacity at ITP would handle sewage from Central Tijuana and the canyons until 2050. San Antonio de Los Buenos treatment plant will treat coastal neighborhood sewage and there would be no discharge at San Antonio de Los Buenos Creek which usually leads to several days of impacted water quality in San Diego, especially during a swell.
The cost of this new alternative is beyond the $300 million budget of the USMCA and more sources of funding will be looked at. The timeline for the Environmental Impact Statement (EIS) Review process has been changed from the past. While at first the EIS was going to cover all the proposed projects, in order to expedite the process, the EPA is looking at doing a first tier review, later followed by the second tier, which is more extensive and expected to take more time. The second tier includes the river diversion which is the most detailed analysis due to the number of species and habitat impacted.
Timelines shown for the ITP expansion sees construction beginning in the third quarter of 2022 and the U.S. side river diversion at the end of 2023.