Tidal Constituents

vibes for the week: intense, toxic vengeful??

Imperial Beach is in San Diego, California and is subject to frequent closings due to high bacteria levels from sewage pollution. The sewage pollution comes from the Tijuana River, which is one of the most polluted rivers in the country. When there is rainfall in the area it floods the river which leads to untreated wastewater/sewage flowing into the Tijuana River which subsequently flows into the Imperial Beach area. This has become an even more complicated issue as the sea spray from the beach contains toxins and bacteria and has started to pollute the air as well. Kim Prather of UC San Diego has said that “We’ve shown that up to three-quarters of the bacteria that you breathe in at Imperial Beach are coming from aerosolization of raw sewage in the surf zone" [1]. The research done by Prather and others does not necessarily mean that people are getting sick due to this, but it points out that contamination from water does not necessarily only come from swimming in the water. This aerosolization also leads to foul smells that permeate the air in the Imperial Beach area which triggers headaches, nausea, eye irritation and respiratory distress. And there are other chemicals, viruses and bacteria in the mix [2]. Another issue that complicates this is that the pollution in the Tijuana River spans multiple countries including the US and Mexico. Improvements need to be made to the wastewater treatment systems in Mexico and in the US in that area so that it does not pollute the Tijuana River. There has been improvements. "The South Bay International Wastewater Treatment Plant... is now fully functioning and expanded its capacity from 25 million to 35 million gallons of wastewater per day." [2]. However, due to federal funding cuts, projects like these and others are threatened. Imperial Beach is one of many coastlines that are polluted and affected by society. It's important to be grateful for our beaches and mindful of the impact we make. The next time you visit the coastline, pick up a piece of trash or try to leave the area better than when you found it! Happy listening!!

Most common Tidal Constituents for Imperial Beach/ San Diego [3];[4]:

M2 (Principal Lunar Semidiurnal): The largest lunar constituent, representing roughly half of the semi-diurnal tidal range.

S2 (Principal Solar Semidiurnal): The largest solar constituent, often combined with M2 to dictate the fortnightly spring/neap cycle.

K1 (Luni-solar Diurnal): A major diurnal constituent affecting the inequality between the two daily high or low tides.

O1 (Lunar Diurnal): A major diurnal constituent.

Cite:

[1] R. Monroe, “Coastal water pollution transfers to the air in sea spray aerosol and reaches people on land,” UC San Diego Today, Mar. 2, 2023. [Online]. Available: https://today.ucsd.edu/story/coastal-water-pollution-transfers-to-the-air-in-sea-spray-aerosol-and-reaches-people-on-land

[2] D. S. Brennan, “Tijuana River sewage still pollutes the San Diego Coast. A surfer turned politician is fighting to clean it up,” CalMatters, Dec. 5, 2025. [Online]. Available: https://calmatters.org/environment/2025/12/tijuana...

[3] National Oceanic and Atmospheric Administration, “Harmonic Analysis,” NOAA Tides & Currents, accessed Feb. 22, 2026. [Online]. Available: https://tidesandcurrents.noaa.gov/harmonic.html

[4] National Oceanic and Atmospheric Administration, NOAA Tides & Currents: Imperial Beach (Station ID 9410120), accessed Feb. 22, 2026. [Online]. Available: https://tidesandcurrents.noaa.gov/stationhome.html...