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| ANNOUNCEMENTS |
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| Devil's Gate Dam Interim Measures 2012 |
| The County of Los Angeles Department of Public Works has completed the annual Interim Measures in Devil’s Gate Reservoir. Sediment and vegetation near the face of the dam was removed from October 9, 2012 to October 29, 2012 for a total of 15 working days. Approximately 1,525 cubic yards of sediment was placed at Johnson Field and 419 cubic yards of green waste was hauled to Scholl Canyon. Similar efforts are expected to take place in fall 2013. |
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More information can be found on the following document:
Interim Measures 2012 Flyer |
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| The 2009 Station Fire was the largest fire in Angeles National Forest (est. 1892) recorded history and burned over 160,000 acres in the San Gabriel Mountains. Approximately 68% of the watershed tributary to Devil's Gate Reservoir (approximately 100% of the undeveloped portion) was burned, making sediment deposition inevitable during subsequent storm events. The storms that occurred in the two wet seasons after the fire increased sediment accumulation in the reservoir by more than one million cubic yards. This major sediment inflow significantly reduced the reservoir's capacity and also buried a large portion of the reservoir vegetation, although significant amounts of vegetation, including numerous mature willow trees remain present. In its current condition, the reservoir no longer has the capacity to safely contain another major debris event; and the outlet works have a risk of becoming clogged and inoperable. |
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| A project to remove sediment from behind Devil's Gate Dam is vital to the health of the Arroyo Seco flood control system. In March 2011, in recognition of stakeholder and environmental concerns, the Los Angeles County Board of Supervisors directed LACFCD to complete an Environmental Impact Report (EIR) which would assess the impacts associated with removing sediment from within the reservoir. The Los Angeles County Board of Supervisors also directed that an Interim Measures Project (IMP) be implemented each year to reduce downstream flood risk until the EIR is completed and a sediment removal project is implemented. During the 2012 Interim Measures 1,525 cubic yards of sediment was removed from the dam face and is temporarily being stored in Johnson Field, a decommissioned spreading basin. |
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The goal of the Devil's Gate Sediment Removal and Management Project is to restore flood control capacity to the facility and establish a reservoir configuration more suitable for routine maintenance activities including sediment management. Primary project objectives include:
- Reducing flood risk to the communities downstream of the reservoir adjacent to the Arroyo Seco by restoring reservoir capacity for flood control and future sediment inflow events;
- Supporting sustainability by establishing a reservoir configuration more suitable for routine maintenance activities including sediment management;
- Removing sediment in front of the dam to facilitate an operational reservoir pool to reduce the possibility of plugging the outlet works with sediment or debris during subsequent storm events;
- Removing sediment placed at Johnson Field during the Devil's Gate Reservoir Interim Measures Project;
- Supporting dam safety by removing sediment accumulated in the reservoir in a timely manner to ensure the ability to empty the reservoir in the event of a dam safety concern;
- Delivering the sediment to placement or reuse facilities that are already prepared and designated to accept material without native vegetation and habitat removal.
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| DEVIL'S GATE EIR PROCESS DIAGRAM: |
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| Current status highlighted in blue. |
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| UPCOMING PUBLIC MEETINGS |
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| To Be Announced |
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| RESOURCES |
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| CONTACTS |
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| For more information on the EIR please contact: reservoircleanouts@dpw.lacounty.gov |
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| Updated on: 04/23/2013 |
