Sunrise light on a grove of tufa towers emerging from the water of Mono Lake with soft green and dusty-red wild grasses in the foreground, Canada geese in the shallow water with reflections of the rocky towers, and desert hills in the distance.

Lee Vining Creek Diversion Dam work planned for September through November

If you are planning a fishing trip to the Lee Vining Creek diversion pond this fall, there will be some construction activity impacting your experience.

This fall there will be construction at the Lee Vining Creek diversion pond, a popular fishing site. Photo by Arya Degnhardt.

The Los Angeles Department of Water & Power (DWP) is going to be working on the Lee Vining Creek facility in September because it discovered it can’t lower the spill gate all the way because sediment has accumulated underneath it. DWP has to put in a temporary cofferdam and remove the sediment, so a large portion of the pond and parking area will be closed to public access from September through November. Due to the last three dry years in a row, the gate hasn’t been lowered all the way since 2011, resulting in the first time a significant amount of sediment has accumulated under the gate since 2008, when it wasn’t fully working following a dry 2007.

The gate was installed in 2005 as a sediment bypass project. It is designed to be lowered all the way during peak spring snowmelt, allowing sediment to pass downstream instead of collecting in the pond. The sediment and peak flows that pass downstream are needed to restore the stream, which was damaged by excessive water diversions that lasted from the 1940s until the 1980s. In dry years, however, there are no required peak flow or sediment releases, and the gate isn’t lowered during the peak flow, resulting in sediment accumulation under the gate. That accumulation, if left in place, would prevent the gate from being lowered all the way as required during the next non-dry-year peak flow and sediment release.

The Lee Vining Creek diversion dam is the northernmost point of the Los Angeles Department of Water & Power's water diversions that flow to Los Angeles through the LA Aqueduct. Photo by Arya Degenhardt.

At the same time that work is being done, additional maintenance will be done on the gate, as well as some repair work on a bypass gate. The pond level will be lowered during the work. Beginning in August there will be heavy equipment in the area, and the public is advised to use caution and consider fishing in other locations.