The beaches in Coronado were closed from Sept. 1 through Sept. 4, along with several South Bay shorelines near the U.S.-Mexico border due to heavy sewage flows entering the beaches from Tijuana.
In an effort to protect public health, the County of San Diego issued water-contact closures for Avenida Lunar to North Beach in Coronado on Labor Day due to discoloration and sewage found in the water. The beaches were still closed the morning of Thursday, Sept. 4, but the closure was lifted later in the evening.
“The water contact closure previously in place for Tijuana Slough and Imperial Beach shorelines and Coronado Avenida Lunar is being extended to include the entire Coronado Shoreline,” said a release issued by the Department of Environmental Health and Quality for Monday, Sept. 1. “The Tijuana River is flowing and reaching recreational waters. Beach goers are advised that the ocean water contains sewage and may cause illness. Ocean waters will remain closed until sampling and field observations confirm these areas are safe for water contact.”
Sampling results permitted beach reopenings on Sept. 4, according to information about closures and liftings available online at sdbeachinfo.com.
A water-contact closure is issued when there is a reported sewage spill, the flows of the Tijuana River reach recreational waters, or verified field reports of odors or water discoloration have been received from lifeguards, beach managers, surfers, swimmers and are confirmed by the county’s Beach and Bay Water Quality Monitoring Program.
The closure remains in effect until county testing shows the water is safe per state standards. The department says it issues closures or advisories when there are more than 1,413 DNA copies of bacteria per 100 ml, which means the sample exceeds state health standards.
To lift a water-contact closure, certain conditions must be met: water sample results meet state standards, an ongoing sewage release is eliminated and zero field reports of odors or water discoloration observations in the beachline.
“While, like everyone who loves our Coronado beaches, I am deeply disappointed that yet another Labor Day holiday weekend delivered closed beaches due to water and air pollution due to sewage and industrial chemicals threatening public health, I am cautiously optimistic that infrastructure projects on both sides of the border are underway and making progress to give us relief,” said Laura Wilkinson Sinton, Coronado resident and cofounder of StoptheSewage.org, calling the situation heartbreaking while also noting the impacts to local business and tourism.
Closures amid progress
Closure signs issued by the county are posted in Coronado to inform beachgoers about the sewage contaminated water that may cause illness.
Even so, residents and visitors on Sept. 4 walked past the signs and down to the beach – some unaware of the sewage crisis impacting Coronado.
Tijuana resident Larissa Veraud said she believes the beaches in Coronado are cleaner than those across the border, such as Rosarito.
“That’s why I came here to San Diego,” said Veraud, who did not know that the beaches in Coronado were closed on Sept. 4.
San Diego resident Luis Rodriguez said he knew about the closures but would proceed to enjoy the beach anyway.
Others agreed with Rodriguez, adding that the signs are a continuous sight.
“Now if you tell me let’s go to Imperial Beach, that water I won’t get in,” said another person near the water’s edge at Coronado Dog Beach.
The beach closures were announced as the U.S. International Boundary and Water Commission expands treatment capacity at the South Bay International Wastewater Treatment Plant (SBIWTP).
On Aug. 28, the commission completed a 100-day plan to rapidly increase the plant’s daily treatment capacity from 25 to 35 million gallons per day (mgd). The IBWC will gradually increase the additional 10 mgd inflow to the plant in the weeks following the project’s 100-day deadline.
“This process is not related to the beach closures since it’s taking sewage that would otherwise end up in the Tijuana River and into the ocean,” said IBWC Public Affairs Officer Frank Fisher.
Fisher said the 35 mgd expansion should keep most of the flow in the river from reaching the U.S. during the dry season, from June through September.
“Rain of course will put more water into the river and likely exceed our plant’s capacity,” said Fisher. “But if Mexico fulfills their obligations under Minute 328 and improves their wastewater infrastructure, less raw sewage should go into the river and the ocean.”
The U.S. and Mexico signed a memorandum of understanding in July that calls for funding and expediting previously identified projects expected to help with the crisis.
Closures follow rainfall
The Mexican pump station Punto de Bombeo de Control Integral Lomas de Agua (PBCILA) diverts flows in the Tijuana River into the Tijuana wastewater system for discharge to the SBIWTP or for ocean discharge at Punta Bandera — reducing transboundary flows in the Tijuana River and impacts to San Diego beaches.
According to Fisher, during the rain last week, PBCILA went offline from Aug. 28 at 3 p.m. through 3 p.m. on Aug. 29. Following this, 42.6 mgd of storm water flowed through the channel and took a few days to get towards the ocean, he said.
Kimberly Prather, an atmospheric chemist at UC San Diego’s Scripps Oceanography and the Department of Chemistry, said untreated discharges through the Tijuana River on Aug. 28 and 29 resulted in flows of 42 mgd and 23 mgd that likely contributed to the Coronado shoreline closure.
“This is ‘dry season’ so that is all unprocessed wastewater entering the ocean,” said Prather.
The San Diego County Air Pollution Control District (SDAPCD) also issued odor advisories to notify the public of elevated levels of hydrogen sulfide (H₂S) produced by the transboundary wastewater and sewage flows near the Tijuana River Valley.
Prather, who co-authored a recent study that found these flows directly contribute to alarming rates of toxic gases in the area, said the hydrogen sulfide levels in the air have gone back up.
On Sept. 1, SDAPCD said measured hydrogen sulfide levels exceeded the state’s threshold of 30 parts per billion (ppB) from 2 a.m. to 3 a.m.
Hydrogen sulfide levels on Aug. 3, ranging from 97 to 108 ppB from 2 a.m. to 6 a.m., also exceeded the threshold.
The district’s Air Improvement Relief Effort program allows eligible households in South San Diego impacted by hydrogen sulfide odors in the Tijuana River Valley to receive purifiers and filters.
Wilkinson Sinton said an ongoing survey, to further assess air and water quality concerns, welcomes input from Coronado residents and visitors.
Researchers from SDSU School of Public Health are conducting that community health survey for anyone living or visiting the areas affected by the sewage crisis. To learn more visit: https://tjriver.sdsu.edu/.
