In the Spotlight: Aqueduct and Reservoir Keepers, the Eyes and Ears of the Los Angeles Aqueduct

One of the biggest responsibilities of an A&R is supporting the irrigation or runoff season to help ensure the delivery of water to Los Angeles while efficiently managing water deliveries to environmental projects, spreading grounds and other LADWP obligations.

When the snow starts melting with warmer temperatures, the runoff season officially begins, typically peaking between May to June. This year is not only expected to be a longer runoff season, heading possibly into September, there is an estimated 326 billion gallons of water traveling through the Owens Valley. Figuring out exactly where all the water is going to go is a major team effort.

The A&Rs worked closely with the Aqueduct Construction and Maintenance crews and began preparations for the 2023-2024 runoff season in late December and until runoff began in April. Aqueduct Construction and Maintenance crews used heavy equipment to build and restore diversion canals and ponds throughout Owens Valley that may have been damaged during the winter storms, in order to help control water this summer. From those canals and ponds, the water goes to “spreading ditches” or spreading grounds. There, an A&R makes sure the water is flowing across the dry landscape, soaking into the soil for groundwater recharge, and is effectively managed.

To make room for the massive amount of snowmelt coming from the Eastern Sierra mountains, engineers in the WOD Aqueduct Section calculated the necessary reservoir storage and LAA water flow changes. For instance, LADWP needed to lower the elevation of Tinemaha Reservoir, located south of Big Pine. It is the A&R’s responsibility to turn the valves to increase the water outflow from the reservoir so the level will come down. This often requires a multiple-step process. Once a flow change is made at Tinemaha, A&Rs then chase that flow south. Water released from Tinemaha soon reaches the LAA and Lower Owens River intake structures. At the intakes, A&Rs must adjust inflows to the aqueduct and to the Lower Owens River while accounting for the capacity available in the aqueduct. A&Rs regulate water flows to different canals and ditches, so when flows are increased or decreased in a canal or ditch, every irrigation ditch feeding off of the canal or ditch must be reset to make sure the water delivery is exactly as much as required, but no more and no less.