The Tijuana River has faced severe water quality challenges for years as untreated or partially treated wastewater, stormwater runoff and industrial discharge cross the border from Mexico, contributing to coastal pollution, beach closures and degraded habitat. The chronic contamination has created significant public health, environmental and economic impacts for communities in San Diego County and officials at all levels of government have sought ways to mitigate the crisis.<\/p>\n
![\"San](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-001.jpg\")
One of the streams in the Tijuana River Valley that flows beneath the bridge on Dairy Mart Road, located along the U.S.-Mexico border in San Diego, CA. (Nelvin C. Cepeda \/ The San Diego Union-Tribune)<\/p>\n
The U.S. International Boundary and Water Commission<\/a> (IBWC), which oversaw the project, said in its contract award<\/a> that it did not put it out to bid because of \u201cthe urgent need to assess the effectiveness of this technology in addressing the public health threat posed by airborne contaminants in the Tijuana River flows. Given the unique capabilities of Greenwater Services\u2019 technology and the immediate need for a solution, it is in the public interest to proceed with this pilot program to validate the technology\u2019s performance.\u201d<\/p>\n IBWC Commissioner Chad McIntosh declined to answer questions about the pilot program, nanobubble ozone technology or its implementation at the Tijuana River.<\/p>\n Al George, CEO of Greenwater Services, said the company approached San Diego officials first, then contacted IBWC about the technology.<\/p>\n \u201cWe were able to obtain the pilot because there\u2019s no other company that does what we do at the capacity that we do it,\u201d he said.<\/p>\n IBWC conducted the pilot project from Sept. 9 to Oct. 15, 2025, just downstream of the international boundary. Operational challenges severely limited the project\u2019s effectiveness. Debris and trash from Mexico repeatedly clogged equipment inputs and output nozzles, forcing operators to restrict treatment to daytime hours only when river flow was lower. The equipment, which has a record of success with stillwater and algae blooms, struggled with the Tijuana River\u2019s fluctuating flows and mixture of sewage effluent, trash and silt.<\/p>\n \u201cWe had trouble keeping the machines running because of all the trash,\u201d said Chas Antinone, president and chief operating officer of Greenwater Services.<\/p>\n On the night of Oct. 14, an unexpected flood surge increased river flow from approximately 40 million cubic meters per second to 247 million cubic meters per second, according to the report. The flooding destroyed NBOT units and auxiliary equipment, caused a 5-gallon diesel spill requiring professional environmental remediation, and forced termination of the project.<\/p>\n Antinone said the company has not done extensive wastewater treatment work.<\/p>\n \u201cWe have not done a lot of that, but we\u2019re tiptoeing in that,\u201d he said, adding most of the company\u2019s testing has been in small bodies of water under 100 acres.<\/p>\n Greenwater also used NBOT in 2024 at the Trump National Golf Club Bedminster in New Jersey during a free demo, Antinone said.\u00a0He said Greenwater wasn\u2019t hired to do any further work at the course, but he expressed interest in pursuing similar opportunities at other golf courses in the future.\u00a0<\/p>\n In terms of its practicality on larger, more dynamic bodies of water such as the Tijuana River, George said the \u201ctechnology is scalable and we can make it bigger or smaller depending on the type of water body that we\u2019re working with.\u201d<\/p>\n While the technology\u2019s infrastructure fell short, its application showed some promise, according to a technical report prepared after the project by the IBWC and Greenwater.<\/p>\n The technology demonstrated bacterial reduction during operation, including coliforms and E. coli. Anecdotal reports included in the technical report cited a reduction in odors around the site as well, though The San Diego Union-Tribune could not independently verify that information.<\/p>\n \u201cWe averaged 93% reduction in bacteria on the days that we treated, which is quite remarkable,\u201d George said.<\/p>\n Peter Moeller, a research chemist at the National Oceanic and Atmospheric Administration who has worked on nanobubble ozone technology for more than a decade, said the approach addresses a fundamental problem with traditional water treatment methods.<\/p>\n \u201cA lot of the things you can treat your reflecting pond with, for example, you can go get copper powder and you can use clay and a bunch of other things to kill algae, but you\u2019re not really taking care of the problem as a whole,\u201d Moeller said in an interview. \u201cIf you kill algae, but they\u2019ve spilled their guts, you\u2019ve got toxins in the water. What are you going to do about that?\u201d<\/p>\n Moeller, who has collaborated with Greenwater Solutions on multiple projects and helped the company on the science behind the technology, said ozone\u2019s power as an oxidant allows it to simultaneously attack living organisms \u2014 like bacteria \u2014 and dissolved contaminants.<\/p>\n The technology uses self-contained units that require only electrical power to operate. The machines bring in air, remove nitrogen to create 95% pure oxygen, then feed that oxygen into an ozone generator. The ozonated water passes through a patented nanobubble generator that creates the microscopic bubbles as water is drawn in and expelled back out.<\/p>\n \u201cOzone doesn\u2019t care if the chemical is part of the living system. It doesn\u2019t care if it\u2019s dissolved in the solution as a contaminant, it\u2019s going to attack them and then destroy them, oxidize them, take them out of the picture in one way or another,\u201d Moeller said. \u201cAnd the beauty is, when we walk away, all we\u2019ve left is oxygen behind.\u201d<\/p>\n The nanobubble delivery system addresses a longstanding concern about ozone treatment. \u201cOzone shouldn\u2019t be played with, it\u2019s toxic,\u201d Moeller acknowledged. But nanobubbles \u2014 which are invisible to the naked eye and don\u2019t float \u2014 provide controlled release over time rather than shocking water with large excess amounts.<\/p>\n \u201cWhen (nanobubbles) implode, they release the hydroxyl radicals and ozone and do their job, imploding over a steady period of time,\u201d Moeller said. \u201cAnd that means you\u2019ve got this time release ability to clean up water. You\u2019re not just shocking it.\u201d<\/p>\n Moeller said testing has shown the technology doesn\u2019t harm non-target aquatic species when operated at low concentrations, and research at Youngstown State University found increased survivability rates for human skin, liver and lung cells in post-treatment water compared to pre-treatment water.<\/p>\n George emphasized the safety profile. \u201cNone of the ozone goes into the air,\u201d he said. \u201cThe byproduct of our treatment is that we actually leave the water more oxygenated.\u201d<\/p>\n Despite the technology\u2019s promise, the Tijuana River application revealed significant equipment limitations. The contractor\u2019s report noted that four NBOT units were deployed with the intention of operating continuously, but debris-related clogging made overnight operation impractical. Daily trash removal was required following debris-filled discharges from Mexico.<\/p>\n Antinone said the modifications needed are primarily filtration-related rather than fundamental technology changes. \u201cYou need a screen of some type where you\u2019re having the inputs and the outputs protected from the garbage that\u2019s coming,\u201d he said.<\/p>\n Moeller said the equipment can be adapted for different applications but acknowledged challenges with moving water.<\/p>\n \u201cMoving water has historically been the biggest\u201d limitation, Moeller said. \u201cBut I think we can overcome that.\u201d<\/p>\n He said full-scale implementation in the Tijuana River would require a different configuration. \u201cIf we were to actually go full time rather than a pilot study in the Tijuana River, we would come up with a different format, probably a floating format,\u201d Moeller said.<\/p>\n The equipment\u2019s modular design allows for customization, according to Moeller. \u201cThere\u2019s only one piece of intellectual property in the entire machine. Everything else comes off the shelf. So it can be re-engineered, retooled, reconfigured to suit,\u201d he said.<\/p>\n However, redesigning equipment for specific applications requires capital investment, he noted.<\/p>\n Despite the equipment challenges, the company reported that the pilot project demonstrated significant bacterial reductions when operational.<\/p>\n Pre-treatment water samples showed severe bacterial contamination, such as E. Coli and coliforms. Post-treatment samples showed substantially lower concentrations, though levels still remained far above standards for human contact.<\/p>\n All water samples were analyzed by Environmental Lab Network, a San Diego-area laboratory. \u201cThis is all third-party data,\u201d Antinone said. \u201cWe grabbed the samples. However, the lab came out on two separate occasions and took samples as well and corroborated what our testing was.\u201d<\/p>\n Odor levels around the site were shown to have reduced, according to the report. The rotten egg smell reported by residents is produced by hydrogen sulfide, a toxic gas that is a byproduct of the sewage.<\/p>\n Moeller attributed the reduction\u00a0to ozone\u2019s ability to oxidize odor-causing compounds. \u201cHydrogen sulfide goes right to sulfate, no odor,\u201d he said.<\/p>\n A well-known\u00a0university researcher disputes the data.<\/p>\n Kimberly Prather, an atmospheric chemist at the University of California San Diego who monitored hydrogen sulfide levels in the air during the pilot project, said the technology didn\u2019t reduce hydrogen sulfide (H2S) emissions from the river.<\/p>\n \u201cI will tell you that we were measuring H2S that whole time and it didn\u2019t change in the air,\u201d Prather said.<\/p>\n Prather, who has conducted extensive measurements of compounds in the Tijuana River, expressed concerns about the pilot project\u2019s limited scope and potential risks to the community.<\/p>\n \u201cIf you bubble a highly reactive species through water, one that has probably thousands of different chemicals that you don\u2019t know what they are, in the middle of a community, and you don\u2019t look at what\u2019s being released in the air, then that\u2019s dangerous and reckless,\u201d she said.<\/p>\n No adverse environmental or public health effects were observed or reported during the pilot, according to the contractor\u2019s report.<\/p>\n Prather emphasized that the Tijuana River presents unique challenges compared to typical wastewater.<\/p>\n \u201cIt is not just sewage,\u201d she said. \u201cIt is sewage, which is what you get in wastewater treatment plants, plus this unknown cocktail of industrial dumping from the factories. Those are the chemicals I\u2019m most worried about.\u201d<\/p>\n The IBWC stated it will continue to investigate and evaluate technologies that can provide relief to U.S. citizens in the region and remains \u201cinterested in potential funding and application partnerships that can demonstrate cost and operationally large-scale effectiveness.\u201d<\/p>\n \u201cWe hope that we can do more work (at the Tijuana River), but we don\u2019t know at this point in time where it\u2019s going to go,\u201d Greenwater\u2019s George said.<\/p>\n Prather said she wouldn\u2019t rule out the technology entirely, but had concerns about its implementation.<\/p>\n \u201cI didn\u2019t have much confidence in the way they were implementing the technology,\u201d she said. \u201cI just don\u2019t think you should take a highly reactive gas and mix it with a thousand unknown chemicals and pray. I just don\u2019t think that\u2019s a good idea.\u201d<\/p>\n Moeller called the technology \u201cthe best I\u2019ve seen for water mitigation in my career,\u201d though he acknowledged bias due to his close collaboration with Greenwater Solutions.<\/p>\n \u201cI know I\u2019m biased,\u201d Moeller said. \u201cBut this concept of \u2018no legacy residues\u2019 is huge \u2014 that we\u2019re not adding a bigger problem to the water than we\u2019re treating. That\u2019s a big deal.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"The federal government awarded a $1.1 million contract to an Ohio company to conduct a pilot project deploying…\n","protected":false},"author":2,"featured_media":148948,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[1697,7,929,181,23,100,74,84,76,75,4067,3055,4931,1696],"class_list":{"0":"post-148947","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-san-diego","8":"tag-baja-california","9":"tag-california","10":"tag-imperial-beach","11":"tag-latest-headlines","12":"tag-local-news","13":"tag-news","14":"tag-san-diego","15":"tag-san-diego-county","16":"tag-san-diego-headlines","17":"tag-san-diego-news","18":"tag-san-ysidro","19":"tag-south-county","20":"tag-tijuana","21":"tag-top-stories-sdut"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/148947","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/comments?post=148947"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/148947\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media\/148948"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media?parent=148947"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/categories?post=148947"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/tags?post=148947"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"San](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-003.jpg\")
The riverbed is dry and littered with garbage from the recent rains. During the rainy season, the steady flowing stream and trash debris feed into the Tijuana River Valley.\u00a0 (Nelvin C. Cepeda \/ The San Diego Union-Tribune)<\/p>\n![\"One](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-007.jpg\")
One of the streams in the Tijuana River Valley that flows beneath the bridge on Dairy Mart Road. (Nelvin C. Cepeda \/ The San Diego Union-Tribune)
\nThe Science Behind the Technology<\/p>\n![\"Trash](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-005.jpg\")
Trash debris left from the last rain storm in San Diego. At the moment the riverbed is dry and littered with garbage from the recent rains. During the rainy season, the steady flowing stream and trash debris feed into the Tijuana River Valley.\u00a0\u00a0 (Nelvin C. Cepeda \/ The San Diego Union-Tribune)<\/p>\n![\"At](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-0091.jpg\")
At the moment the riverbed is dry. However, during the rainy season, the stream flows steadily with trash debris that feeds into the Tijuana River Valley.\u00a0 (Nelvin C. Cepeda \/ The San Diego Union-Tribune)
\nEquipment Limitations and Adaptability<\/p>\n![\"Trash](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-010.jpg\")
Trash debris left from the last rain storm in San Diego. \u00a0 (Nelvin C. Cepeda \/ The San Diego Union-Tribune)
\nWater Quality Results and Community Response<\/p>\n![\"One](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/01\/sut-l-nanobubbles-008.jpg\")
One of the streams in the Tijuana River Valley that flows beneath the bridge on Dairy Mart Road, located along the U.S.-Mexico border in San Diego, CA. (Nelvin C. Cepeda \/ The San Diego Union-Tribune)
\nProcurement and Future Plans<\/p>\n