Stormwater Engineering Projects

Picture of Big Tujunga Dam


Thank you to those of you who submitted comments on the Initial Study/Mitigated Negative Declaration (IS/MND), for the Big Tujunga Reservoir Sediment Removal Project. The 45-day extended comment period ended on June 26, 2013. However, you may still view the IS/MND by clicking the links in the Resources section below.

The Cogswell Reservoir Sediment Removal Project proposes to remove the accumulated sediment from Cogswell Reservoir up-to approximately 2.6 million cubic yards. The Station Fire resulted in an additional 1.1 million cubic yards of debris. This brings the total debris and sediment in the reservoir to 3.1 million cubic yards. This material must be removed as soon as possible to comply with United States Forest Service permitting requirements and to maintain the Dam as a fully functional component of Los Angeles County Flood Control System.

For additional project information, please click the links below:

Please click here to read the Project FAQs.
Please click here to read the IS/MND presentation slides.
Please click here to view photos from the Public Informational Meeting for the project IS/MND.


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 87% of the watershed tributary to Big Tujunga Reservoir was burned, making sediment deposition inevitable during subsequent storm events. The storms that occurred in the wet seasons after the fire increased sediment accumulation in the reservoir by more than one million cubic yards.

The sediment in the reservoir can impact the operation of the valves and reduce the capacity for water conservation and flood control. Sediment removal is necessary to maintain the operability of the dam and protect the communities and environment downstream of the dam.

Pursuant to the California Environmental Quality Act (CEQA) a Mitigated Negative Declaration (MND) has been prepared. You may view the document by clicking the links in the Environmental Documents section.

Big Tujunga Reservoir before the Station Fire
Big Tujunga Reservoir after the Station Fire
Pursuant to the National Environmental Policy Act (NEPA) an Environmental Assessment (EA) is being prepared. A public scoping meeting was conducted by the United States Forest Service on July 24, 2012 in Tujunga, CA and included this linked Big Tujunga Presentation.

Maple Canyon Sediment Placement Site Big Tujunga Reservoir Project Map Photo Taken After Big Tujunga Dam Seismic Rehabilitation and Spillway Modification Project



For more information on the project or to be added to the porject mailing list, please contact
Updated on: 04/10/2014