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Reservoirs will help ease impact of dry winter for the year

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POSTED February 13, 2018 1:37 a.m.

Almost every major reservoir in Northern California is currently holding more than its historical average.
It’s the state’s ace in the hole against the possibility of 2018 turning into a drought year.
With the exception of Lake Oroville – the second-largest reservoir in California, which is holding only 61 percent of its historical average – reservoirs from the northernmost reaches of the state all the way down to Fresno are holding more water now than they traditionally do, a good sign for the health of the state’s water system that was taxed further than ever before prior to the historic 2016/17 rainy season that caused flooding and led to several close calls at other points throughout the state.
While certain reservoirs, like Lake Don Pedro and New Melones Reservoir, will be releasing large amounts of water in the coming month for “pulse flows” intended to aid in the restoration of the state’s salmon population, both are far above where they normally are – with Don Pedro holding 119 percent of the water typically measured at this point of the season, and is 83 percent full, while New Melones is holding almost 40 percent more than its historical average and is also 83 percent full.
And both are being managed differently in respect to inflow coming from warmer than expected weather that is thawing the Central Sierra snowpack.
New Melones, which as of Feb. 7 had roughly 550 cubic feet per second flowing into the reservoir, has showed a steady increase in the amount of water being released from 212 cubic feet per second the first few days of February up to more than 1,100 cubic feet per second flowing out as of Wednesday morning.
Don Pedro, on the other hand, has nearly 900 cubic feet per second flowing into the reservoir, and save for a spike in releases that temporarily rose up to above 750 cubic feet per second in late January, has been holding steady with releases of around 325 cubic feet per second since November.
Last year in February the excessive rain overwhelmed operators at New Melones who were forced to open the spillway gates for the first time since 1997 – when large swaths of South San Joaquin County flooded – and flooding was prevented in part because New Melones had ample space to hold back the massive inflows and release only a minimal amount of water as to not have downstream impacts that would have threatened the levees protecting hundreds of homeowners in South Manteca.
In the coming months, the State of California will continue to conduct snow surveys throughout the Sierra Nevada, which will give a clearer picture of how many acre feet of water have yet to melt and give dam operators a better idea of how to manage through the rainy season while still maintaining enough water for residential and agricultural uses.
According to Accuweather, temperatures are expected to drop back into the 60’s for the majority of the rest of the month with only a handful of days where rain is expected.
To contact reporter Jason Campbell email jcampbell@mantecabulletin.com or call 209.249.3544.

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