Mono Basin: Export

Export refers to the portion of the Sierra Gauged Runoff that is diverrted from its historical course to the lake. You've read that export is the key policy variable in the model in chapter 4. A typical "business as usual" value of the export might be set at around 100 KAF/yr based on Vorster's review of exports in the years prior to the legal challenge to LA's water rights in the basin. The photo shows part of the LADWP's equipment to bring the water exports south to the Owens Valley. Notice the man standing next to the pipe, and you can appreciate the capability for large export flows. Export can vary tremendously from one year to the next depending on operational and legal constraints. In 1979, for example, surface water export was 141 KAF/yr. In 1969, the export was only 6 KAF/yr.

LADWP Pipe for Mono Basin Export (photo courtesy of the Mono Lake Committee).

Vorster notes that LA's previous water rights would not allow surface export to exceed a legal limit of 167 KAF/yr. Also, because of the location of the diversion gates, surface export would not normally exceed 85% of the Sierra Gauged Runoff. And finally, one should be cautious about large surface water exports in "wet" years. In such years, large exports may not be needed because of the large flows to the south in the Owens Valley. (For example, in the years 1941 to 1947, just after the LA aqueduct was extended to the Mono Basin, large flows from the Owens Valley provided most of the water demand in Los Angeles. For these years, export from the Mono Basin was limited to only 17 KAF/yr.)

The total export from the basin is a combination of the surface water export (ie, 100 KAF/yr) and ground water export. Vorster estimates the ground water export at 7.3 KAF/yr. This flow is part of the other out flows in the basin. More details on how LADWP collects the Sierra Gauged Runoff for export is shown in their diagram of the "Lee Vining Conduit."