PALMDALE — The Board of Directors for the Palmdale Water District unanimously approved, on Monday, a contract with the United States Geological Survey to conduct a study on the effects of the Bobcat Fire.
The Sediment and Storage Capacity Study on the Littlerock Reservoir will measure the amount of sedimentation, the changes in storage capacity and the physical characteristics of the deposited sediment in the reservoir for the next four years.
Scott Rogers, the district’s engineering and grant manager said a representative from the United States Forest Service recommended reaching out to the USGS to look at water quality impacts from the fire.
“I reached out to USGS and started discussing the possibility of working with them in conjunction to perform this study,” he said.
The Littlerock Reservoir is located downstream from the Bobcat Fire burn area. Wildfires increase erosion potential by removing vegetation that intercepts rainfall and reduces soil infiltration capacity.
Because the Littlerock Creek watershed has areas of steep terrain burned by the fire, the potential exists for increased erosion, sediment run-off and debris flow during post-fire rainfall events. The increased sediment run-off will reduce the storage capacity of the reservoir.
Measurements of the amount of sedimentation are needed for reservoir operations and already planned sediment maintenance activities.
Because the effects of wildfires can persist for multiple years post-fire, a four-year time-frame is needed to properly monitor the program.
“(USGS) proposed a proposal to do the sediment removal over the next four years,” Rogers said. “Based on their analysis, they think that the impacts from the fire will be over a three year period.”
The reservoir will be surveyed in the spring of each year, when it is typically full, to document the volume of sedimentation that occurred over the winter rainy season.
The results of the study will be documented and the USGS has committed to publishing the findings in a peer-reviewed scientific journal.
Rogers said the report will give the District the ability to assess the impacts on the reservoir’s storage capacity, which could lead to other funding options for the impacts from the Bobcat Fire.
The District and the USGS California Water Science Center agreed in a joint operation, to fund the study.
“We discussed what kind of funding they would provide to us and they committed to 25% of labor and travel costs for them to perform the study,” Rogers said.
The USGS will cover an estimated $35,800, while the district is responsible for the remaining balance of $173,300, for a total cost of $209,100 over the next four years. The study is budgeted as Work Order No. 20-816 – Bobcat Fire Impact Costs.