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Settlement Finally Reached In Devil's Gate Dam "Big Dig" Lawsuit

A tractor prepares to haul away a freshly-cut eucalyptus tree from the sediment-choked Devil's Gate Dam reservoir on Nov. 28, 2018. (Sharon McNary/LAist)
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Devil's Gate Dam keeps the rain that falls on parts of the San Gabriel Mountains from flooding downstream communities along the Arroyo Seco channel, from Pasadena to the Los Angeles River.

Heavy rains that followed the 2009 Station Fire washed more than a million cubic yards of ash and debris from the burned watershed into the reservoir above the dam. All that sediment reduced the capacity of the dam to hold back floodwater, so it needed to come out.

But in 2014, environmentalists with the Audubon Society and the Arroyo Seco Foundation sued over the scope of the plan. They said its footprint was so big it would strip out too much of the forest-like growth, birds and other wildlife that had come to occupy the acreage behind the dam, and that trucks coming in and out all day with sediment loads would be a major disturbance.

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The L.A. County Board of Supervisors voted to approve asettlement on Tuesday that pays the two groups' legal costs, totaling $333,000, and requires them to dismiss the legal actions and not challenge the sediment removal project any further.


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Devil's Gate Dam as it appeared in 2015 following a rainstorm. (Sharon McNary/KPCC)


The main benefit is that a smaller footprint of land was cleared. A 14-acre tract of trees and plants that would have been taken down has been left intact. Less dirt will be removed as well. The original plan called for taking out 2.4 million cubic yards of soil, and that was cut back to 1.7 million cubic yards.

Once that dirt is removed, the county agrees to remove no more than 220,000 cubic yards of new sediment per year, and to keep the dirt-hauling truck traffic to no more than 300 trips per day.

The Arroyo Seco Foundation and Pasadena Audubon Society got the county to agree to leave parts of the basin below the dam in a more natural state. So rather than earthmovers coming and scraping the area bare at regular intervals, that kind of work will be done less frequently. The agreement also calls on the county Flood Control District to release less water downstream, so that some pooling of water can build up behind the dam to support wildlife in the area.

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The organizations pushed for the county's work to be done with the cleanest trucks available.

The settlement requires the county and its habitat restoration contractor to buy native plants and seeds from the Arroyo Seco Foundation. That's a deal that should be good for at least $10,000 a year and possibly as much as $48,000. Also, the county will pay up to $50,000 for the Audubon Society to build three bird blinds, which are shelters that enable people to watch birds in their habitats but without disturbing them.

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