A tentative cease-and-desist order is being considered by a California water protection agency to enforce effluent discharge regulations as the U.S. International Boundary and Water Commission moves forward with a 100-day plan to rapidly increase the South Bay International Wastewater Treatment Plant’s daily treatment capacity.
The IBWC, as the boundary commission is known, this year announced plans to fast-track expansion of the sewage plant, increasing treatment volume by 10 million gallons per day (mgd).
The San Diego Regional Water Quality Control Board noted the IBWC’s target date in late August does not allow sufficient time to amend the agency’s National Pollutant Discharge Eliminations System (NPDES) permit. The water board, however, indicated it intends to amend the NPDES permit prior to its expiration date, June 30 of next year.
Until then, the board will discuss an order on Aug. 27, ahead of the Aug. 28 target date, that requires the IBWC’s compliance with the permit’s final effluent limitations.
Tentative order
According to the water board, the expedited treatment plan does not comply with the commission’s water pollution permit.
The cease-and-desist order says the water board anticipates the IBWC will not be able to comply with the final effluent limitations for carbonaceous biochemical oxygen demand, total suspended solids, settleable solids, and turbidity in the permit until the plant’s complete expansion is completed and eliminates expected bypass and blending.
This tentative order comes weeks after the U.S. and Mexico signed a memorandum addressing the Tijuana sewage crisis in which the nations reinforced a commitment to fund and expedite previously identified projects which would mitigate untreated wastewater that pollutes coastal communities, harms public health and threatens the environment on both sides of the border.
That memorandum identifies the expanded treatment capacity of the plant from 25 to 50 million gallons per day (mgd) by the end of 2027. The binational pact also calls for an interim expansion by Aug. 28 of this year, temporarily bringing the plant’s capacity to 35 mgd.
“This 10 MGD is really critical so that there’s no flow in the river during the dry season, and the construction of the expansion (for the plant) can move at the schedule it needs to move,” said former IBWC commissioner Maria-Elena Giner.
The waterboard’s order, to be discussed in late August, requires the IBWC “to take appropriate remedial and preventative action and to comply” with a time schedule concerning the treatment of additional domestic and industrial wastewater from Tijuana.
According to Giner, collaboration between the regulator and permittee is procedure, in this case the water board is working with the IBWC to make them successful.
This is a go ahead the IBWC says allows for the planned expansion if requirements and schedules are met.
“The cease-and-desist order will allow us to process the extra 10 mgd,” said IBWC Public Affairs Officer Frank Fisher in a statement.
In the meantime, the order lists over half a dozen actions which the IBWC must comply with to address discharges of waste that threaten violation of its NPDES permit.
San Diego Regional Water Quality Control Board Executive Officer David Gibson said the water board would be moving forward with amending the IBWC’s permit at the board’s meeting in June of 2025.
On Aug. 13, IBWC representatives presented updates of the commission’s progress on plant upgrades and other infrastructure improvements, including the expansion.
“Removing 10 mgd of raw sewage out of the Tijuana River and estuary, treating it to at least ‘Advanced Primary,’ and then discharging it via the ocean outfall three miles out to sea will result in a massive improvement for public health and the environment,” said Patrick McDonough, senior attorney for the environmental organization San Diego Coastkeeper.
McDonough, a longtime advocate on the crisis who gave public comment at that board meeting in August, echoed the order’s concerns about the 10 mgd expansion only treating the effluent to the “Advanced Primary Treatment” standard and not the legally required “Secondary Treatment” standard, which the IBWC will then blend with the plant’s 25 mgd that will be treated to secondary standards.
According to McDonough, amending a Clean Water Act Permit takes many months, sometimes years.
For this reason, the tentative cease-and-desist order is necessary amid the expansion to 35 mgd at the plant and functions as a legal permit.
“This project has happened so fast that it is not possible for the regulators to go through the normal permit amendment process,” he said.
McDonough said Coastkeeper supports the order because so long as it’s in place, and the plant’s interim expansion complies with the terms of the order, the IBWC will not be violating its permit.
“San Diego Coastkeeper is supportive of plans for the rapid expansion of the South Bay International Wastewater Treatment Plant’s capacity from 25 mgd to 35 mgd, as well as the tentative cease and desist order,” said McDonough who called the expansion “the fastest significant infrastructure construction on the U.S. side” addressing the crisis in more than three decades.
“I don’t think (the IBWC has) as much opportunity for failure because the plant is strong right now,” said Giner, who led the agency through a separate time schedule to fix the plant after Tropical Storm Hilary, and eventually reached compliance in November 2024 following an August deadline.
The water board scheduled a public hearing for consideration of a tentative cease-and-desist order at 9 a.m. on Wednesday, Aug. 27 in the boardroom at 2375 Northside Drive, Suite 100, Room 108 in San Diego.
