Is it true that enterococci bacteria can be caused by decaying kelp and why doesn’t the City think the current advisory at Avenida del Sol is related to sewage impacts from the Tijuana River or Mexico

The City has been challenged to explain why the San Diego County Department of Environmental Health issued a beach advisory just before the Fourth of July holiday. The advisory, which remains in effect, warns swimmers to avoid water contact in the area near Avenida del Sol in South Beach. The City made an educated guess that the elevated levels of enterococci bacteria were a result of the decaying kelp that washed ashore in the area where the high levels were recorded. Decaying kelp is normal for this time of year when ocean temperatures rise. Many strands of kelp die and release from the kelp beds offshore. Regional, scientific studies tie enterococci to environmental sources, specifically, kelp. Here is an excerpt from one study:

"While there is no evidence showing that enterococci can grow in ambient oligotrophic waters (environments that offer very low levels of nutrients), experiments showed enterococci can grow in sands (Yamahara, Walters, and Boehm, 2009) as well as in water augmented with decaying kelp (Byappanahalli, Shively, Nevers, Sadowsky, and Whitman, 2003; Imamura, Thompson, Boehm, and Jay, 2011)."

The exact reason for the high levels of enterococci bacteria in the area in late June and early July may not ever be known. However, it is very unlikely caused by sewage from the Tijuana River for many reasons, the least of which is that beaches closer to the border did not test positive for any sewage contaminants. In fact, the City of Coronado's waters tested only for enterococci, not fecal coliform or total coliform. Fecal matter is always present in human waste (sewage) contaminated waters. Additionally, the ocean currents in the area during the dates of the elevated enterococci readings were flowing north to south during the entire time of the elevated samples, (see images below). This is compelling evidence that whatever caused the higher levels of bacteria at the South Beach location could not have originated in Tijuana. According to Keith Kezer with the County Department of Environmental Health:

"It is unlikely that the advisory at Avenida del Sol is related to sewage impacts associated with the Tijuana River Valley or Mexico. A routine sampling at these locations, which ranges from one to three times each week, has not detected water quality indicative of sewage impacts from Mexico and has almost exclusively been below state established beach water quality health standards."

A sewer discharge always leaves a trail of bacteria. If the source of the contamination was Tijuana sewage, the concentration of contamination near the source would be highest and progressively become more diluted as it traveled away from the source. There is no means for contamination from the mouth of the Tijuana River Estuary to travel 10 miles north without contaminating all points in between.

Ocean currents June 26, 2018


Ocean Currents June 1, 2018

Ocean Currents July 5, 2018

Show All Answers

1. Was the Coronado Senior Association moved out of the John D. Spreckels Center to make room for the City’s Cultural Arts senior management analyst?
2. Since the Spreckels Center does not have the word “senior” anywhere on the facility, does the City have a true “senior center” that addresses the needs of those 50 and older?
3. Do I have to recycle my food waste now that EDCO has announced its new Organic Recycling Program?
4. Why does the City waste money watering the synthetic turf at the Lawn Bowling Green?
5. Does the City’s affordable housing provider San Diego Interfaith Housing treat tenants in an arbitrary, unpredictable, discriminatory fashion and evict people without cause?
6. Are the current asphalt repairs simply “make-work” and unnecessary?
7. Are there fresh water aquifers in Coronado that could be used for a supply of potable water?
8. Did the City of Newport Beach successfully challenge a state law, Senate Bill 2, that mandates a city's zoning codes accommodate emergency shelters and transitional housing?
9. Did the new traffic signal at Alameda Boulevard and Fourth Street cause a back-up of traffic east of the intersection on Wednesday, November 6?
10. Does refinancing the former redevelopment agency’s bonds and loans create more density in Coronado?
11. Does the City’s affordable housing provider San Diego Interfaith Housing treat tenants in an arbitrary, unpredictable, discriminatory fashion and evict people without cause?
12. How can the City leave the lights on at the Coronado Public Library overnight especially during the current heat wave and with potential rotating outages?
13. How does a City get selected to Dr. Beach’s Top 10 Best Beaches in America list?
14. Is it true that enterococci bacteria can be caused by decaying kelp and why doesn’t the City think the current advisory at Avenida del Sol is related to sewage impacts from the Tijuana River or Mexico
15. Is the City going to make changes at Coronado Cays Park?
16. Is the City not respecting its beautiful historic sidewalks?
17. Is the City trying to extend San Diego’s Lindbergh Field into Coronado?
18. Is the water quality being affected in South Beach and is Central Beach being tested for the Fourth of July?
19. Is there still time to have a say on the Coronado Cays Park Master Plan?
20. It has been reported in national news stories based on a local report that the City of Coronado’s beach was closed for several weeks. Is that true?
21. Questions have come up in the community about what uses are allowed in the City of Coronado’s R-1A residential zoning code. What are those uses?
22. The City has fire rings at North Beach that get very busy during the summer. What is the City’s fire ring policy? How does the City monitor behavior at the fire rings and is it enough?
23. What are the white cones along the Silver Strand State Highway?
24. Is the National Citizen Survey conducted by the National Research Center valid?
25. What is the current status of the Golf Course Water Recycling and Turf Care Facility project or the environmental review? How are the potential environmental impacts being addressed?
26. What role does the City have in the redevelopment of the Coramart building and has the City prevented its redevelopment?
27. What was the odor in Coronado on Easter Sunday?
28. Why are there two construction sites at Spreckels Park? And why is the site near Seventh only a concrete pad?
29. Why is the City ending its participation in the Rotary Santa program?
30. Why isn’t the City extending service to the Cays this year?
31. Why were two palms recently removed from the beach?
32. Why is the Glorietta Bay Boat Launch Ramp closed and when will it reopen?