The 2012-2013 water year is on the right track for the first time, with year-to-date precipitation of 110.5 percent of average for this date.
But the water picture could have been even rosier had December’s early storms delivered their expected yield.
“Actually, what the storms yielded was about 70 percent of what was forecast,” said Turlock Irrigation District Utility Analyst Jason Carkeet.
So far, 4.34 inches of precipitation have fallen in the TID watershed this December. Year-to-date, 9.69 inches have fallen.
The most recent rainstorms led to a 7 foot elevation change in TID’s Don Pedro Reservoir in a matter of days, accounting for about 33,000 acre-feet of water.
The sudden surge came as most precipitation reached the ground as rainfall, melting what little snow lay on the ground. The resulting melt filled the reservoir, but left little snow as carryover storage to melt later this spring.
In total, 135,000 acre-feet of water have flowed through the Tuolumne River watershed this water year – 126.9 percent of average.
That’s actually less water than TID might have expected in a normal water year, as last year was one of the driest on record. Thirsty trees drink up as much as 30 percent of rainfall in years after dry years.
Despite the helpful precipitation, the district needs more rainfall to fill Don Pedro, now at its fourth lowest level in the past 20 years.
A further inch-to-inch-and-a-half of precipitation is expected in the next week, likely coming as snow; the snowline is projected to fall as low as 5,000 feet.