Dry January Worsens Irrigation Season Outlook

An unexpectedly rainy December had Turlock Irrigation District forecasters envisioning a wet irrigation season, despite a dry 2011-2012 water year.

But an extremely dry January – totaling only .32 inches of precipitation so far – has undone those early forecasts.

“We’re right on track with the average now,” said TID Board Chairman Michael Frantz. “We’ve given up our early gains.”

The TID watershed recorded 11.77 inches of precipitation in December, nearly double the historical average of 5.96 inches. That rainfall, plus a better-than-average November, put total accumulated precipitation at 133 percent of normal at the close of December.

But with less than one-half inch of rain in January thus far – well below the historical monthly yield of 6.53 inches – projections now suggest an average water year.

As of Tuesday, a total of 17.43 inches of precipitation have fallen in the Tuolumne River watershed, where TID sources its irrigation water. That’s 101.2 percent of the 50-year average rainfall for that date.

Snow sensors tell a similar tale, with snow pack levels currently resting at 111.5 percent of average.

As January is historically the rainiest month, the lack of rainfall could lead to an average overall water year. Following a historically dry 2011-2012 water year, a simply “average” water year may not be enough to forestall low irrigation allotments.

There’s still time left for precipitation to fall in January. But TID forecasts currently call for less than 1.5 inches of rain and snow to fall in the next 8 days.

At the close of January, the water year will be approximately 50 percent complete.