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Water year just ended was way above-average for Modesto area. Was it a record?

River runoff was strong, and reservoir storage was high, with Monday’s end of the water year for Modesto-area suppliers.

The Tuolumne River watershed had 2.98 million acre-feet of runoff in the year ending Sept. 30, 2019, said Constance Anderson, communications division manager with the Turlock Irrigation District. It shares Don Pedro Reservoir on this river with the Modesto Irrigation District.

The Tuolumne runoff was 156 percent of the historical average, but it was far from the record 255 percent two years ago.

The Stanislaus River watershed got 1.75 million acre-feet of runoff in the year ending Monday, said General Manager Steve Knell of the Oakdale Irrigation District. It was 153 percent of average, well short of the record 274 percent two years ago.

Having two very wet years in the last three has helped the state recover from the five-year drought earlier in the decade.

“We’re in good shape heading into the 2019-2020 water year,” said Melissa Williams, public affairs manager at MID. “Together with our watershed partners, we remain cognizant of California’s dynamic weather patterns and actively plan for a wide range of hydrologic conditions.”

Many water agencies measure the supplies from October to the next September so it includes the stormy months followed by the irrigation season. Others measure from July 1 to June 30.

The abundant rain and snowmelt mean above-average reservoir storage, which will come in handy if the new water year is drier. The readings from the California Department of Water Resources as of Monday:

  • Don Pedro was 84 percent full, and at 124 percent of its historical average for this time of year.
  • New Melones Reservoir on the Stanislaus River was 85 percent full and at 151 percent of its historical average. It stores water for OID and the South San Joaquin Irrigation District, and for federal water customers in the western and southern San Joaquin Valley.
  • McClure Reservoir on the Merced River was 68 percent full and at 151 percent of its historical average. It is owned by the Merced Irrigation District.
  • San Luis Reservoir in the hills west of Los Banos was 62 percent full and at 132 percent of the historical average. It holds water pumped from the Sacramento-San Joaquin Delta for numerous Valley districts.

Groundwater levels have risen, too, thanks in part to recharge from the storms since 2017. Some suppliers urge farmers to flood-irrigate if possible near season’s end, to further build up the aquifers.

Knell said the Oakdale district has an especially large effort thanks to extensive land that is cattle pasture.

“With one of the largest flood-irrigated pasture lands areas in the region, nearly 30,000 acres, this late-season irrigation opportunity has proven its benefits to our local aquifer,” he said.

The state agency noted that more than 30 atmospheric rivers – highly concentrated bands of moisture in the sky – hit California in the past water year. And it warned that the new year could be vastly different.

“What we could have today could be gone tomorrow,” DWR Director Karla Nemeth said in a news release. “Conserve. Recycle. Recharge. People and the environment depend on it.”

John Holland covers breaking news and has been with The Modesto Bee since 2000. He has covered agriculture for the Bee and at newspapers in Sonora and Visalia. He was born and raised in San Francisco and has a journalism degree from UC Berkeley.
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