Our hearts go out to everyone impacted by the recent wildfires in Los Angeles and Ventura counties. As we learned from the Thomas Fire in 2017 and subsequent mudslides, there will likely be severe ocean water quality issues once it rains and the question that many of us will be asking ourselves is when will it be safe to go in the ocean?
Until the Pacific Coast Highway is fully open, be sure to observe evacuation notices and road closures so that fire crews and first responders can do their jobs unabated. As of November 15th, there is one water quality warning in the fire area at Surfrider Beach Malibu Lagoon that bacteria levels exceed state standards according to Los Angeles County Public Health and the unhealthy air quality in some areas is starting to improve.
While most of Los Angeles County suffers from urban runoff every time it rains more than 0.1 inch, Malibu, especially western Malibu, is much less developed than the rest of Los Angeles. As such, this area typically does not see as much of the traditional urban runoff from streets and sidewalks that leads to high levels of bacteria in the ocean, but due to the ongoing fires, close attention to rain and water quality should be paid in the coming months. The National Weather Service has a great online guide to Post Wildfire Flash Flood and Debris Flow.
The water quality impacts will be correlated to how much rain falls and the extent to which mudslides occur near the ocean or coastal waterways, as these factors determine the level of stormwater runoff. This runoff can bring high levels of nutrients, pesticides and animal waste from agricultural areas; debris from compromised buildings and developments that could include heavy metals and household chemicals; sewage or untreated wastewater from damaged infrastructure; and more to county beaches and coastal waters. People should follow Los Angeles County Public Health for general advisories and water quality results. Their webpage is available here: http://publichealth.lacounty.gov/phcommon/public/eh/water_quality/beach_grades.cfm
Water quality tests are typically delayed two days because of the time needed to process samples. The general advisory for most of Southern California is that once it rains more than 0.1 inch, people should stay out of the water for at least 72 hours. If you can see brown water from runoff, that's a sign to stay out of the water because bacteria levels are likely very high.
A good rule of thumb for surfers and ocean lovers is 'if you are in doubt, don't go out'.
Photo: Graham Hamilton / Surfrider LA