Five-Year Study Finds L.A. River Watershed Isn't Too Bad, But Could Be Better


L.A. River. Andrew Hart/Flickr/Creative Commons.

There has never been a comprehensive and continuous monitoring of the Los Angeles River watershed that would tell us definitively if Los Angeles is doing a good job at keeping its waters and surrounding ecosystems clean. Until now.

On October 10, the Council for Watershed Health will release the initial results of its five-year study of the Los Angeles River watershed, which they call the Los Angeles River Watershed-wide Monitoring Program (LARWMP).

Nancy Steele, Executive Director for the Council, sums up the results of this first report this way. "Overall, things are not bad. They're not really, really good, but they're not really, really horrible." Steele says that the results of the report provide a baseline for future reports that focus on the same measures. When aggregated, Los Angeles would better see if its revitalization efforts (including the ARBOR study) have actually made a difference. The report hopes to be a barometer for policymakers to make better decisions when it comes to water projects in Los Angeles.

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Developed in 2007 by a group of conservationists and public agencies, the report drills the health of the Los Angeles River watershed down to five specific questions:​ 

What is the condition of streams in the watershed?

Are conditions at areas of unique interest getting better or worse?

Are receiving waters near discharges meeting water quality objectives?

Is it safe to swim?

Are locally caught fish safe to eat?

The group answered these questions by sampling over fifty sites, scattered on different areas of the watershed in the last five years. (If you recall, we tagged along once.)

As expected, the team found that areas unlined with concrete had more biological diversity. Incidentally, sample sites within the 2009 Station Fire, which was started by an arsonist, showed that the area still has not recovered from the damage that ravaged 252 square miles.


Algae at Malibu Creek | Alyse & Remi/Flickr/Creative Commons

Unlike the results of the Malibu Creek Watershed report released by Heal the Bay last March, the Los Angeles watershed actually benefited from water treatment.

At the Malibu Creek watershed, water discharge produced additional nitrogen, which promotes algae growth that sucks up the oxygen, harming aquatic life. This wasn't the case in the Los Angeles watershed. While studying three publicly-owned water treatment plants, the Council found less concentrations of dissolved metals, bacteria that indicate the presence of feces and any suspended solids. "The Los Angeles City and Burbank treatment plans conduct tertiary de-nitrification process that remove the excess nitrogen from the water before returning it back to the river," explained Kristy Morris, senior scientist at the Council.

Answers to the last two questions are probably the most relevant to the public. While sampling alongside the Council last year, the question most often asked of Rickey Russell was, "Is it safe to swim?" The answer is, the more people in the water, the more bacteria there is. Bacteria levels are also higher on weekends and holidays. "But we don't know if that affects human health. That requires a different kind of study," says Steele. The Council is searching for partners to conduct a separate study on where these bacteria come from, and determine if it's harmful to humans. That study is expected to include recommendations to reduce bacteria in these places.

For fishermen who have taken to reaping the bounty of the Los Angeles River, fish in the river have been found to have lower concentrations of contaminants selenium, DDT pesticide, and PCB often found in motor fluids. The only exception is the largemouth bass, says Morris. The report finds high mercury levels on this type of fish. It suggests staying away from bass, if you plan to digest your catch.

The study is the first step of many more to come. As it progresses, the Council hopes it would provide a clearer picture of the whole Los Angeles River watershed. It would track how the public efforts at restoration and revitalization have really accomplished its goals of improving the county's natural environment.

Hear the full results of the report at the State of the Los Angeles River Watershed conference October 10. 

A 4-page executive summary of the results will be posted on the Council's website at the end of the week. A more comprehensive report is due to be published end-November.


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