When a grizzly bear surfs woody debris…

December 1, 2011 § 6 Comments

…you know there’s trouble.

Image source: Alaska Wood Carvings. Click image for link.

I had originally begun drafting this post as a follow on to Trouble at the Waterworks, which recounted how the significant rains of 1867 sent piles flying and reduced LA’s zanja system to carted water. These rains offer some insight to just how gnarly a 500-year storm could be, something that circulates in the news from time to time. It’s worthwhile to appreciate how much these rains can shift our rivers, when the human hand isn’t busily doing it, that is. Driving that shift: loads of debris from the mountains washing down.

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Symposium Explores the Complexities of Sediment Management

September 29, 2011 § 7 Comments

1969. A conveyor belt transports sediment away from Big Tujunga Reservoir. (Los Angeles Public Library Images)

Last Tuesday (9/20), the Council for Watershed Health (formerly the Los Angeles & San Gabriel Rivers Watershed Council) hosted a creek-freaky event entitled Shifting Soil: Sediment Management Policies in Los Angeles. While I was fortunate enough to be in attendance, it has taken some time to digest all that was discussed and to place in context all of the remarks that were made. The following is my best attempt at a summary including a few thoughts on the topic. For further reading, have a gander at Mademoiselle Gramophone’s in depth coverage (including video and audio snippets) or visit the Council’s event archive for downloadable PDF files of each presentation. A friendly forewarning: this post is a lengthy one… « Read the rest of this entry »

Got silt? Oak woodland to become dirt pile.

December 4, 2010 § 6 Comments

A perennial management problem for our channelized, dammed river system is sediment. Natural rivers use sediment to shape and reshape their channels and floodplains – in fact the channel dimensions reflect the most efficient way for it to move that sediment.

Not so in our engineered systems. Dams trap sediment, while over-wide channels cause it to drop out, foster colonies of vegetation: both reduce flood capacity. So as long as we have people living in floodways and an engineered system, there will be jobs-for-life for the guys who truck out dirt.
What’s bewildering is where to put all this sediment. Again, nature distributes it along the floodplain, and ultimately the finest material makes it to coastal wetlands and the beaches. Not so, today. If the County has its way, it will raze an 11-acre century-old oak woodland in Arcadia to make space for dirt piles.

Funny, ’cause when I look at a map of the Arcadia-Monrovia area, near the imperiled oak grove, I see a lot of very big holes in the ground. (if any aren’t used for water recharge, what’s the big? Store it there, at least until we can get a grip on better ways to manage this stuff) Or consider the salinization problem with soil in our nearby Central Valley ag lands - wouldn’t good soil be a resource that increases our food security?

The fact is, local government is acting like parking lots have more intrinsic value than these oak woodlands, described as being in a canyon – will a stream also be impacted?

Equally disappointing, however, is that this proposal went through a 2-year environmental review process – and made it through unscathed. As much as I appreciate that we even have a public process and environmental protections, clearly they don’t go far enough to ensure that the public actually knows what’s on the table. The news didn’t cover this when it was a proposal, but waited til it was a crisis. And environmental regulations, as I feel I drone on and on about, don’t necessarily protect natural resources so much as lay out a process for evaluating and “mitigating” the loss of natural resources. But how do you mitigate time? It took one century for these trees to grow to the state that we appreciate them today. Streams flow for millenia and then are abruptly filled. And how can you agree that the mitigation will provide the same quality of habitat when 11 acres is being cleared on one site and the mitigation project will take place on acreage half that size with three times the number of trees? How will overcrowding those trees be an effective way to ensure no net loss?

You can let your Supervisor know how you feel about this:

D1: Gloria Molina: molina@bos.lacounty.gov
SD2: Mark Ridley-Thomas: markridley-thomas@bos.lacounty.gov
SD3: Zev Yaroslavsky: zev@bos.lacounty.gov
SD4:For Don Knabe: Aaron Nevarez handles enviro/public works issues-anevarez@lacbos.org
SD5: Mike Antonovich: fifthdistrict@lacbos.org

News Sources:

San Gabriel Valley Tribune: Last ditch effort to save pristine native woodland from clearance

Los Angeles Times: Century-old oaks in the San Gabriel Mountains may make way — for silt – latimes.com.

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