As another dry winter comes to a close in Inyo County, the Los Angeles Department of Water and Power (LADWP) has announced its annual Owens Valley Operation Plan and groundwater pumping program for the 2013-2014 runoff year. Typically, the LADWP proposes a 1-year pumping plan, releasing the plan to Inyo County with a 10-day period for comment, followed by an Inyo/Los Angeles Technical Group meeting. But after two successive drought years, the Water Agreement between Inyo and Los Angeles now requires the LADWP to execute this year’s Operation Plan in two, 6-month periods.
The current pumping plan is based upon the Eastern Sierra Runoff Forecast, which anticipates an annual runoff 54% of normal, or 220,900 acre-feet rather than the 1961-2010 average of 412,284 acre-feet. “The Forecast can be 5% to 10% off,” said Inyo County Water Department Director Bob Harrington. Depending on information gathered during April to October of this year, the LADWP will issue its second, 6-month Operation plan on October 20.
Thus far, the Operation Plan for April 1-October 1 proposes pumping 47,370-54,660 acre-feet of groundwater from the Owens Valley. The pumping plan cover letter indicated that the LADWP will pump a total of about 70,000 acre-feet over the course of the year. “For a year this dry, it’s a pretty reasonable level of pumping,” said Harrington. “There have been similar drought years where 2 to 3 times this amount of water has been pumped.”
Last year, another year with very low runoff, the LADWP pumped 88,600 acre-feet from the Owens Valley. Even that figure pales in comparison to the most water pumped in one year: 209,00 acre-feet in 1987, according to Harrington.
The Operation Plan also proposes that, should the County forego some pumping for its own irrigation purposes, the pumping plan will require water in the low, rather than the high 70,000 acre-feet range. “That’s one of the issues the Inyo County Board of Supervisors will have to grapple with,” said Harrington; “whether to agree to reductions in irrigation during the current runoff year.” The Board of Supervisors will discuss this and other pumping plan issues at a special meeting on Monday, April 29.
While the DWP uses the Runoff Forecast to determine what it considers a reasonable amount of groundwater pumping in the Owens Valley this year, the Inyo County Water Department is also “scrambling to figure out, by well field, how much what the DWP is planning would change the water table and effect groundwater and vegetation,” said Harrington. Last year, he reported, water tables in the Valley dropped between a foot and a few feet, “from a combination of pumping and low recharge from runoff.”
Inyo County has objected to LADWP pumping projections in the past, particularly concerning well fields in sensitive areas near Independence and Laws (see “Inyo County, LADWP hit a bump in the pump”). These areas include the Taboose-Aberdeen, Thibaut-Sawmill, and Independence-Oak well fields. The 2013-14 pumping plan proposes pumping between 4,200 and 7,380 feet at Taboose-Aberdeen, 6,800 acre-feet at Thibaut-Sawmill, and about 5,300 acre-feet at Independence-Oak.
However, the LADWP will return some 198,800 acre-feet to the Valley for irrigation, stockwater, recreation and wildlife projects. Dust mitigation on Owens Lake could require the return of as much as 95,000 acre-feet, although, said Harrington, “to date, the most they’ve used is 75,000.” He added, “That’s still a big amount of water.”