Water quality beneath the asphalt

Those wondering why so much of the recent rain across Los Angeles was flushed out to the Pacific through a storm drain system instead of socked into the local aquifer will find part of a complicated answer in a fact sheet issued last week by the US Geological Survey. Run-off from the Transverse Ranges into the San Fernando and San Gabriel valleys hits land that the USGS classes as 83% urban, which means largely paved and impermeable. (For how a combination of arrogance and greed led to over-building of the Los Angeles flood plain, there is no better source than historian Jared Orsi’s “Hazardous Metropolis.”) Another  limit on our ability to store mountain run-off  in these valleys is groundwater pollution brought by that urbanization. The map below shows solvent hot spots. 

Hat tip to the Water Education Foundation’s Aquafornia for signalling the sheet’s publication.

Water spoken here

This USGS poster of the water cycle was spotted on TajikWater.net. It turns out that the USGS has versions in dozens of languages. Click on the image for the international resource.

Disaster denied

“Southern California foothill communities escaped potentially disastrous debris flows from fire-scarred mountains during last week’s storms because total rainfall was far less than expected, the U.S. Geological Survey said Wednesday.”

Click here to keep reading the AP report in the San Francisco Chronicle about how Southern Californian foothill communities were lucky during the last rain, but how they are far from immune to deadly mudslides as the rainy season continues. Via Aquafornia.

Or, if you live in the foothills and you are still thinking about staying in your house the next time a big storm rolls through, click here to read the USGS  “Emergency Assessment of Postfire Debris-Flow Hazards for the 2009 Station Fire, San Gabriel Mountains, Southern California”


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    Emily Green by e-mail at emily.green [at] mac.com
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