Sediment Removal FAQs

The Devil’s Gate Dam provides flood protection for downstream cities of Pasadena, South Pasadena and Los Angeles. Significant storms over the years have resulted in the build-up of sediment in the reservoir behind the dam. The proposed project would remove accumulated sediment from the reservoir over a period of four years.
Sediment removal entails removing trees, bushes and dirt that have flowed into the watershed following the 2009 Station Fire and subsequent rainy seasons, when runoff from the San Gabriel Mountains flowed into the burn area. Without removing sediment, the reservoir does not have the capacity to safely contain flooding or runoff from future storms.
The project is being managed by the Los Angeles County Flood Control District. The final project was approved by the County Board of Supervisors in November 2017.
Altogether, 1.7 million cubic yards of sediment will be removed by diesel powered trucks mostly from Hahamonga Watershed Park located within the reservoir area. All of the diesel powered trucks allowed on-site will meet or exceed air quality standards for low-emissions vehicles. The project also includes on-site habitat restoration, access road construction and invasive vegetation removal.
The sediment removal process will begin in April of 2019 and run through November of 2022.
We do not anticipate that sediment removal will affect daily camp activities. Tom Sawyer Camp remains committed to the idea that every child should experience carefree, constructive outdoor activities.
One aspect of the project involves removing invasive species from the watershed, and re-planting native species that have not been present in the watershed since the Station Fire in 2009. Throughout the duration of the project, campers will still be allowed to learn through outdoor activities and explore the diverse habitat of the watershed.
We are working with the County and the local air district to make sure there is ample testing of the trucks and construction equipment to ensure they comply with all emissions standards and required mitigation measures. In fact, in response to the collective efforts of the camp and other stakeholders, the County will be going above and beyond the required mitigation and measurement processes.
We are aware that two parents challenged the County’s health risk assessment for the project and have concerns about students at the high school having regular exposure to truck emissions throughout the school year. We are very focused on our camp’s unique situation. Our campers will attend camp up to 49 days total throughout the summer, while the County’s health risk assessment made assumptions based on years of exposure year-round.
Yes. We hired an independent expert who analyzed the County’s health risk assessment, which concluded there is a less than significant impact on public health. Our independent expert also conducted a more focused analysis on the camp, our campers and staff. This analysis concluded there was a less than significant impact on both our campers and staff because they are only on-site for a limited number of days, and our camp is located a safe distance from the worksite.
No camp activities overlap with the sediment removal process. The County has also assured us that there will be fencing around active work areas. We will be working closely with the County throughout the summer to ensure that our campers and camp activities do not come into contact with trucks or access roads.
You can find more project-specific information on the County’s website:

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