LORP endured huge flows and impacts in 2023
LADWP staff currently assessing effects
One the unique aspects of the record-setting 2023 runoff year was the diversion of massive amounts of water into the Lower Owens River Project. In previous record runoff years, in 1982 and 1969, the Lower Owens River was a dry channel from the LA Aqueduct Intake south to the delta of the Owens Lake.
When the Los Angeles Department of Water and Power put water back in the 62-river miles of the LORP in the early 2000s, the controlled water releases were pegged at 40 cubic feet per second for most of the year with “pulse” flows topping 200 cfs.
There were no plans for the “new” river to handle flows between 700 and 1,100 cfs for weeks at a time.
But faced with runoff hitting about 244% of normal in 2023, that is exactly what happened. All that snowmelt had to go somewhere. Despite extensive “water spreading” in the Owens Valley the Owens River carried huge volumes of runoff that eventually went into the LORP.
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Plus, with the aqueduct running at capacity, and then breeching and breaking for a short spell, the LORP became a major water-moving channel during the runoff year.
Then, to top off the runoff year, the remnants of Hurricane Hilary dumped unprecedented amounts of rain on the Owens Valley and that rain runoff also found its way into the LORP.
The impacts of those huge flows are now being studied and assessed by staff from LADWP and the Inyo County Water Department (ICWD). At a recent meeting to kick-off the 2023 LORP Annual Report, some interesting information surfaced about what did and didn’t happen to the LORP during the record year.
Peak runoff
For most of the peak runoff season, the LORP
saw flows around 400 cfs, said Tony Tillemans of LADWP. However the Hilary storm resulted in a huge jump in flows. Tillemans said during the August 2023 storm the flows peaked at 1,170 cfs. That was the reading at the Pump Station at the end of the LORP channel just before the Owens
Lake Delta. Thus, it was likely higher flows hit some sections of the LORP before the Pump Station.
Those big flows in the LORP ended up on the Owens Lake and contributed to the “re-watering” of the lake.
The long-running, high flows meant there was no release of a “seasonal flow” aimed at helping flush the river channel, said Tillemans. Also, the Blackrock Waterfowl Area mitigation project included more than the mandated 500 acres of flooding. Actual acreage was not estimated because the area was simply too flooded to get crews on the ground to estimate the total acreage underwater.
The high flows meant there was no work to dry down some of the ponds in the project and rid them of tules and cattails, he noted. That aspect of the Blackrock project was recently implemented and helped improve bird and waterfowl habitat.
The big flows and water spreading in the Blackrock area did attract more than the average number of waterfowl and other birds, said David Livingston of LADWP. The avian survey spotted about 22,000 birds, including waterfowl, shorebirds and wading birds. About 65% of those birds were “indicator species” that are used as signs of success of the flooding and habitat work, he noted.
The high flows flooded out and damaged numerous county roads crossing over the river, including Mazourka Canyon Road, outside Independence, the Lone Pine Narrow Guage Road north of Lone Pine and SR 136, south of Lone
Pine.
Ongoing issues
What kind of changes those flows created in the river channel itself is still being determined, said Larry Freilich, of the Inyo County Water Department.
One of the ongoing issues with the LORP channel has been the abundance of tules and cattails in the channel itself. There is some evidence that the flows did impact the tule growths, but more extensive mapping and observations of the channel are needed.
Water quality was an issue during the high runoff, but it appeared fish in the LORP were only “stressed,” and there were no notable fish die-offs, said ICWA Hydrologist
Tim Moore.
In general, the high flows threw off the regular monitoring efforts by both Inyo County and LADWP staff, who were unable to access the LORP during the high flows due to access issues and safety concerns.