"Over the last five winters, we had four below-normal rainfall years," Patzert said. "Last winter we had a much touted and advertised El Niño, but [rainfall] turned out to be just slightly above average."
Now, El Niño is in the rearview mirror, Patzert said. And early data indicate that La Niña — a global weather phenomena characterized by cold equatorial waters, tropical Atlantic storms and less rain in the American Southwest — is building.
"The deck is stacked for a dry winter, as long as this La Niña continues to develop and strengthen," Patzert said.
The slightly wetter-than-average year did build the Sierra Nevada snowpack to a peak water content of 33 inches in April, and statewide reservoir storage increased to 76% of capacity, according to the California Department of Water Resources. The state's largest reservoir, Lake Oroville, collected more than 1.4 million acre feet of water through the winter.
Nevertheless, Lake Oroville is at just 69% of capacity. And the Klamath and Lake Tahoe basins also remain below average. In addition, environmental restrictions in the Sacramento-San Joaquin Delta limit the amount of water that can be pumped to the Southern California.
The Metropolitan Water District of Southern California announced in April that it would reduce for the second consecutive year allocations to its 26 member agencies, including Foothill Municipal Water District, which serves eight member agencies in La Cañada Flintridge, La Crescenta and Pasadena.
"Even though it was a little-bit-above-average year, the reserves here in Southern California have dropped," said Nina Jazmadarian, general manager of the Foothill Municipal Water District. "We are still trying to build up those reserves."