Tuesday morning, boards meeting 14 miles apart will look to a common goal – keeping their Don Pedro Reservoir supply from running out this year.
Directors of the Modesto and Turlock irrigation districts will consider water allotments that are roughly half of what farmers enjoy in years of adequate rain and snow.
The MID staff recommends capping deliveries at 18 inches per acre – a foot and a half of water delivered over the irrigation season. The TID staff proposes a 20-inch cap.
The MID proposal is tied up with a rate increase, which could be derailed under state law if more than half of the affected land owners protest at or before an April 15 hearing.
MID could order a similar reduction for water treated for domestic use in Modesto and a few smaller locales, which set their own rules on conserving the supply.
MID’s share of the current Don Pedro storage is only 60 percent of what it diverts from the Tuolumne River in an average year, said John Davids, civil engineering manager, in a report to his board Friday.
“Thus, it is prudent to continue planning for what is likely to turn out to be a critically dry year with curtailed water supplies (and subsequently deliveries) for MID agricultural and urban customers,” he wrote.
The scant river supply likely means increased use of groundwater by the districts and individual farmers. The cuts also could force farmers into tough decisions, such as fallowing some fields used for their annual crops to keep orchards and vineyards producing. Growers on fast-draining soils could have an especially hard time, as could dairy farmers hoping to grow their own feed.
The irrigation seasons would be several weeks shorter than usual under the staff proposals — March 23 to Sept. 19 for MID and March 27 to Oct. 8 for TID.
The proposed cuts are not as bad as in much of the Central Valley, where the main federal and state systems project zero water for most farmers this year. But they are tough nonetheless for a pair of districts that usually have reliable supplies from the Tuolumne.
TID and MID were established a few weeks apart in 1887 and built canals and other waterworks in the decades that followed. Don Pedro, completed in 1971, has had enough carryover storage from average and wet years to get the districts through most droughts.
The current dry run is now in it third year and is an especially bad one. The Tuolumne would have just 31 percent of its normal runoff even if the next few months bring average rain and snow, said Mike Kavarian, water distribution manager for TID, in a memo to his board. Continued dry weather could drop the runoff to 21 percent, he said, which could mean “zero carryover for irrigation the following year.”
Don Pedro would not simply empty out. Some water would be held over for 2015 to meet required flows in the lower river for fish. And the lowest part of the reservoir is the “dead pool,” sitting below the outlets and unavailable to the districts.
To deal with the 2014 conditions, both districts propose to ease the way for farmers to transfer water among themselves. They also plan to minimize spills out the ends of canals, which end up in other bodies of water.
TID has about 150,000 acres of irrigated land in an area stretching from south Modesto to north Merced County and from the lower Sierra Nevada foothills to the San Joaquin River. MID supplies about 58,000 farmland acres just north of TID.