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Where the nasty bacteria in Malibu come from




E. coliFecal Indicator Bacteria. I love saying it. But I'm trying to be careful in reporting on John Izbicki's study because the issue of where the Fecal Indicator Bacteria come from is a hot one in Malibu these days. 

[My radio report can be heard here.]

In my reading of the USGS 8-page summary and charts, what I saw that I could clearly report was simply that where scientists might have expected to find FIB that leached out of septic tanks through groundwater to the Lagoon and Surfrider, they didn't. So the bacteria they detected...came from other places. They're still working out exactly how much, and from where, the bacteria came. They can trace it through genetic, biological, and chemical markers, which is pretty cool. 

Izbicki and others have their suspicions about other sources of bacteria. Some of those suspicions are referenced in the USGS press release for the study, here's how they phrase it

Tests show that FIB concentrations routinely exceed U.S. Environmental Protection Agency public health standards for marine recreational water in Malibu Lagoon and occasionally exceed those standards at several Malibu beaches.

According to preliminary results of the study, scientists suspect possible sources of FIB to the ocean are kelp accumulated on the beach, discharge from Malibu Lagoon to the ocean, or movement of water from the lagoon through the sand berm separating the lagoon from the ocean. Scientists hope to know the exact source of the FIB to the near-shore ocean and the Malibu Lagoon once the study is complete.

I left these suspicions out of my reporting. I left out the kelp. Other places mentioned these suspicions. But that didn't seem to be what the study was about. 

The other thing is: the study IS designed "to know the exact source of the FIB to the near-shore ocean and the Malibu Lagoon once the study's complete." But it takes a picture, sort of, more than a movie, if you see what I'm saying. Izbicki and his team took samples during wet and dry season, two different weeks, hundreds of samples, and that is significant data. A big pile of samples, from a pile of locations. The limitation in this case seems to be time. You do learn different things from that study than you learn from a study done over the course of a year, or a study done in wet years, when the water table is high, and the septic systems may or may not be overburdened.

Another thing I left out of this story was...another study. UCLA scientists released a study back in March that examined the relationship between kelp and fecal indicator bacteria. They looked at wrack - the kelp that high tide leaves in a line on the beach. They found that wrack-kelp could be a huge haven for fecal indicator bacteria. I haven't done reporting on that study, but I wish I would have had time to. 

(Incidentally, wrack has an awesome etymological history - WGBH has a super interesting post about it here: "The terms 'wrack' and 'wreck' come from the same Middle Dutch word, 'wrak,' which means 'something damaged,' as in 'wrack and ruin.'")

The point of all this, of course, is to say science possesses nuance that non-scientists struggle with, and it's easy to forget that. Julian Barnes said, "The desire to reach conclusions is a sign of human stupidity," and even though he's one of my favorite authors, and he's being wryly harsh, and he wasn't probably talking about science, he's got a point.