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Water sent from Eastern Sierra to L.A. down by 35 percent; more than 150,000 acre-feet of water may go to ‘in-valley’ uses
By Jon Klusmire Register Staff
It’s official: The drought of 2006-07 was historic.
The lack of snowfall and resulting puny snowpack and wretched runoff will translate into the second lowest amount of water in history being exported from the Owens Valley to the City of Los Angeles. The L.A. Aqueduct will carry only 115,091 acre-feet of water southward to the city in 2007-08, which will account for a mere 17 percent of the city’s water supply, as opposed to the 62 percent that came from the Eastern Sierra last year, according to the final Los Angeles Department of Water and Power Owens Valley Operations Plan for Runoff Year 2007-08. The only time less water went down the aqueduct was in 1990, when right at 100,000 a.f. were exported. Total Owens Valley runoff for the year was pegged at 58 percent of average, and that snow pile produced a mere 241,300 a.f. of runoff (an average year produces 415,725 a.f. of runoff). The Mono Basin runoff was just 52 percent of average, and will produce an estimated 63,900 a.f. of water. It also appears that 2007-08 could be a historic year because it might see more water remaining in the Owens Valley for “in-valley uses” than LADWP will ship south for consumption in Los Angeles. The amount of water that could end up running through the Owens Valley in 2007-08 might top 150,000 a.f., depending on the progress of various projects and other considerations. Groundwater pumping totals will also be at the low end of the historic totals, coming in at between 56,000-63,000 a.f. for the pumping year, which started April 1. The final Operations Plan lays out two scenarios, and two totals for groundwater pumping in 2007-08. The first plan sets out the same levels of pumping and water spreading that the courts imposed on LADWP for the past two years. Under the court restrictions, LADWP would pump 56,194 a.f. (that total represents the court’s upper pumping limit of 57,412 minus the 1,218 a.f. of water pumped over that limit in 2006-07 for “freeze protection”). Under the court order, LADWP will also spread about 16,000 a.f. of water in the Laws wellfield. That’s the first plan. However, the second plan is based on the Interim Management Plan calculations agreed to by Inyo County and LADWP. Under those figures, LADWP would pump about 63,233 a.f. of water (that’s a slight increase from the 61,950 a.f. of pumping proposed in the draft operations plan). The IMP pumping levels would come into play when the court-mandated pumping limits are lifted. That will occur as soon as LADWP proves it has maintained the required level of flows in the Lower Owens River. While LADWP has tried to convince the courts it has indeed maintained the necessary 40 cubic feet per second of water running in the Lower Owens, Judge Lee Cooper has yet to agree his entire court order has been met, and thus has not lifted the pumping limits or the $5,000 a day fine being paid by LADWP. The final deadline for meeting the court’s orders is July 25 of this year. The court-mandated pump total represents, essentially, all the “must-do pumping” in the Owens Valley, which includes providing water for town water systems, mandated irrigation and ongoing enhancement and mitigation projects, such as providing water to fish hatcheries and wood lots. Inyo County’s comments on the draft Operations Plan centered on the need to outline pumping operations under both the court’s guidelines and the IMP. The IMP was put in place to allow LADWP and the county to fairly quickly calculate pumping totals so more effort can be put into revising the Green Book, which contains the technical guidelines for groundwater pumping water management in the valley. The county and LADWP have agreed there is a definite need to revise the Green Book, and this drought year puts the Green Book’s shortcoming in the spotlight. About 140,000 a.f. of water would be “available for pumping” based on the on/off protocols in the Green Book that have been used to determine total pumping amounts in the county. The on/off protocols are based on vegetation cover, soil moisture and other data. Both the county and LADWP agree the on/off provisions can distort the amount that can be pumped in both wet and dry years. The IMP is based on the water levels in underground aquifers in each individual wellfield. The main thrust of the IMP is to manage pumping during the three-year duration of the plan with the goal of maintaining or increasing aquifer water levels. That won’t happen this year, however, because, despite the low pumping amounts, in general there isn’t enough runoff and recharge to keep aquifers from dropping. Even with the puny snowpack, the potential for “water mining” in Big Pine will be avoided. With the amount of water available for pumping in the Big Pine wellfield running at more than 23,000 a.f. and pumping pegged at only 20,400 a.f. for the year, there should be little chance that long-term pumping totals will outstrip long-term recharge totals in the wellfield. As for in-valley uses, they will almost match the amount of water being sent down the aqueduct, without counting the large volumes of water that will be targeted for dust-control efforts on the Owens Dry Lake. The Operations Plan notes that full allotments of irrigation water and stock water will be provided for lessees this year. About 54,100 a.f. of irrigation water will flow through the valley, with another 12,300 a.f. of stockwater running in ditches and canals. Enhancement and mitigation projects will consume about 11,450 a.f., with “recreation and wildlife” water totalling about 7,800 a.f. The Lower Owens River Project will need about 18,000 a.f. to keep the base flows of 40 c.f.s. flowing. The total for all those “in-valley uses” is about 103,650 a.f. of water. The ongoing dust-suppression effort at the Owens Dry Lake will pump up that “in-valley” total by at least a third, and maybe even more. Last year, the LADWP used about 38,400 a.f. of water for shallow flooding on a large section of the 30 square miles of lake that was “treated” for dust suppression. If that amount of water continues to flow onto the lake, the Owens Valley will, for probably the first time in history, be “consuming” or otherwise using more of LADWP’s Owens Valley water and the City of Los Angeles. In the coming years, the LADWP will have to complete dust-control work on an additional 12.7 square miles on the dry lake. Although a pilot program will be tested involving using dirt rows and ditches to slow the wind and dust coming off the lake, the LADWP has estimated that shallow flooding of the additional acreage could increase water use on the lake to about 54,000 a.f. a year.
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