Introduction

Some of the world’s most scenic and famous coastline resides within the borders of San Diego County. Tourists and locals alike flock to San Diego beaches for surf and sun but the picturesque Socal beach day we all crave may be slipping away. In the past decade San Diego beach water quality has been experiencing severely higher levels of bacterial matter that has forced an increased amount of public beach closures. The source of contamination can be traced back to an aging sewage treatment facility in Tijuana that has deteriorated, causing leakage of raw sewage into the Pacific.

Pre-existing California coast water monitoring stations have noticed spikes in the presence of E Coli and fecal matter present in ocean water and are working to address the root of the issue with cross border policy implementation.(1) San Diego County government, alongside residential advocacy groups, are determined to restore water quality and daily access to safe and healthy beaches for the entire community. In August, the U.S and Mexico signed a treaty pledging to spend nearly half a billion dollars to upgrade the treatment facilities to meet EPA standards (EPA.gov). However, the project is projected to take nearly a decade to reach completion. In the meantime, unsafe water quality and routine beach closures will remain prevalent.

The matter of San Diego ocean water quality is a public health issue. While pre-existing infrastructure, such as beachwatch data collection sites, are continuing to sample ocean water for excessive bacteria particulate matter, the data isn’t getting out fast enough. Sites such as ‘safetoswim’ and ‘sdbeachinfo’ are working to publish water quality advisories as routinely as possible but there can still be delays upwards of 2 weeks between publications. Aside from issues of faster water testing these sites are not well publicized or fully accessible to the public. As a born and raised San Diegan my only source of ocean water quality was a small banner floating across the morning news. There needs to be greater awareness about daily water quality levels, as E Coli and sewage bacteria exposure/ingestion can cause vomiting, fever and infection that is highly dangerous to residents and tourists alike. (6)

Locating the Leak

Figure 1: Cross Boundary Sewage System produced by epa.gov

Looking at the graphic above, you can follow where the SABTP and the PB CILA sewage processing facilities are contaminating cross boundary waterways. The PB CILA facility leaks directly into the Tijuana River while the SABTP plant leaks into the Pacific Ocean, causing dual impact at the base of San Diego’s imperial beach coastline. Aside from processing facility leaks, neglected smaller pumping stations are also contaminating San Diego’s protected wetlands and estuaries. As the cross boundary sewage processing system has continued to age, it forces the increase of unsafe ocean water quality conditions. In the past decade there continues to be a steady increase in the amount of days shut down by bacterial standards violations annually.(4)

Figure 2: Beach Closures 2010-2022 produced with data from data.ca.gov

The data above is in regard to annual beach closure advisories issued for unsafe swimming water quality. This data was collected along the San Diego County shoreline over the last two decades and published by the California Water Board. The three closure types listed above are all in direct relation to the declining integrity of the sewage treatment system. Sewage spills occur less frequently but contaminate ocean water in more concentrated amounts that cause long term closures. The Tijuana river causes more frequent contamination and is especially potent during the rainy season when there is increased stream flow into the pacific (5). In the past decade there is relatively consistent increase in overall beach advisories issued. Its also important to note that these advisories tend to cluster at the base of San Diego county near the mouth of the Tijuana river. Other shorelines further up the coast have a much smaller contribution to the annual advisory total as you will see in interactive map 2 below.

Environmental Justice Aspect

There are several beach communities that have been experiencing chronic water advisories. Imperial beach and San Ysidro experience, on average, 200 plus beach closures annually due to toxic water quality.(4) Using Census median income data for San Diego County in conjunction with the path of Tijuana River flow, I found that these chronically affected regions are also low income. Sadly, there is no surprise that lowest income families are being disproportionately affected by the sewage leak. Over the last decade these communities continue to decline as wealth moves up the coast to areas less affected by the unsafe ocean water quality.

The first map has census income data gathered from 2020 while the second map projects the same data from 2010. Zoom in and look at the decline in wealth where the Tijuana river flows through San Diego county neighborhoods. You can see a clear shift in the median income of the area surrounding the river in the past decade.

Interactive Map 1: San Diego Estimated Income and Tijuana river flow 2020

Interactive Map 1.2: San Diego Estimated Income and Tijuana river flow 2010

As you can see, there is a visible decline in wealth surrounding the populated Tijuana river basin and estuary. Increased wealth allows for mobility, meaning that those who remain in the area likely have no other housing options.If the issue is not resolved promptly, San Diego will face increased population congestion in the upper portion of the county and expedited biodiversity loss in the already scarce estuary and lagoon ecosystem.

Cross Boundary Solution

The infrastructure plan proposed by California legislature, calls for expanding the existing South Bay International Treatment Plant owned and operated by the U.S. International Boundary and Water Commission. (1) The treatment plant is situated on the U.S. side of the international border and must double its current 25-million-gallon waste water treatment capacity by 35 million gallons a day to fulfill this plan. (3) Also included in the plan is a new 5-million-gallon San Antonio de Los Buenos treatment plant in Mexico and the installation of Tijuana River trash booms which would divert up to 60 million gallons a day of Tijuana River water to a new facility for treatment and reuse in mexico. (3) With these plans in affect, there is estimated to be a 95% reduction in the amount of impaired water quality days affecting the San Diego imperial Beach region(EPA.gov).

Now that the projects have been selected the EPA is conducting environmental reviews before moving forward with construction. The expansion project would treat all sewage from central Tijuana and canyons until 2050. The sewage that pools in canyons and has been documented as sickening agents with Customs and Border Protection and is predicted to have significantly reduced with the completed project. The second environmental review will evaluate projects related to U.S.-side Tijuana River diversion, which EPA engineer Doug Eberhardt said, “will take longer to analyze due to potential impacts on riparian habitat in the Tijuana Estuary, where certain species are protected by the Endangered Species Act” (EPA.gov 2021). EPA officials said they expected most if not all the $300 million in USMCA funding to spend on infrastructure projects on the U.S.-side of the border. The price tag and timeline established for this project has created some hesitancy within California state legislator. The majority of representatives from southern California understand the necessity of this health crisis but are unsure of what temporary preventative measures can be taken in the meanwhile.

Interactive Map 2: San Diego County Water Testing Sites

The interactive map above shows the regularly impacted regions along the imperial beach region. This data was taken from the California safe to swim data base. The dots are representative of water quality testing sites along the San Diego County shoreline. The red dots are sites that have experienced more than 150 closures every year over the past decade due to sewage contamination.

Conclusion

The EPA and California state legislature have made the necessary strides forward to implement a large scale renovation of the cross boundary sewage treatment system causing unsafe water quality. However, the bureaucratic systems in place to affect change are working far to slowly for the the local residents and wildlife affected by the issue. While researching this topic I noticed the scarcity of ocean water quality data that is easily accessible to the public. The majority of the data I used had to be requested or heavily ‘cleaned’ before I was able to make sense of it. Sites like safetoswim.com try their best to make data more available to the public but lack speed and mass publication. Along with the plan to revamp the treatment system, I propose the California State Water Board increases funding for water quality testing sites along the coast. This would allow for increased staff, more frequent testing and a better publication system, such as an app, that would get real time water quality updates to the public effectively. I would also encourage San Diego county to increase river clean up initiatives and increase habitat restoration for the Tijuana estuary.

Link to R script

References

  1. Environmental Protection Agency. (n.d.). U.S. and Mexico agree to invest $474M to address Tijuana River sewage problem. EPA. Retrieved December 8, 2022, from https://www.epa.gov/newsreleases/us-and-mexico-agree-invest-474m-address-tijuana-river-sewage-problem address-tijuana-river-sewage-problem

  2. http://www.sdbeachinfo.com/#

  3. EPA selects Tijuana Sewage Pollution Projects for Environmental Review. Courthouse News Service. (n.d.). Retrieved December 8, 2022, from https://www.courthousenews.com/epa-selects-tijuana-sewage-pollution-projects-for-environmental-review/

  4. https://mywaterquality.ca.gov/safe_to_swim/interactive_map/

  5. Ayad, M., Li, J., Holt, B., & Lee, C. (2020). Analysis and classification of stormwater and wastewater runoff from the Tijuana River using remote sensing imagery. Frontiers in Environmental Science, 8, 240. https://doi.org/10.3389/fenvs.2020.599030

  6. Boehm, A. B., & Soller, J. (2020). Refined ambient water quality thresholds for human-associated fecal indicator HF183 for recreational waters with and without co-occurring gull fecal contamination. Microbial Risk Analysis, 16, 100139. https://doi.org/10.1016/j.mran.2020.100139

  7. ARCADIS. (2019). Tijuana river diversion study (Technical report). North American Development Bank. Retrieved from https://www.nadb.org/uploads/files/tijuana_river_diversion_study_final_report_full_sm.pdfGoogle Scholar

  8. Brophy, T. (2016). Environmental and community health in south San Diego County: A behavior analysis of recreational ocean users along Imperial Beach, California (Unpublished master’s thesis, Graduate Theses and Dissertations). University of South Florida. Retrieved from http://scholarcommons.usf.edu/etd/6186Google Scholar