MONTHLY HYDROLOGY REPORT as of January 31

Prepared by Robert Shibatani exclusively for Maven's Notebook

As of January 31, 2019

Our speculation on New Year’s Day that there was no reason to worry about the State’s water supply storage condition holds true today. All hydroclimatic metrics at this point, the end of January, show no signs of concern. The State and Reclamation are staying cautious, as they always do, and there is no surprise or alarm with their conservative forecasts.

As of January 31st, total north CVP water storage was about 8.5 million acre-feet (or almost 75% of the system total capacity). For this time of year, however, we’re doing fine, living off of earlier carryover as they say. North CVP water storage is about 124% of the 15-year average and Oroville Reservoir is at 114% of its 15-year average. Compared to this same last year, total north CVP storage is about 825,000 AF higher. Oroville itself is over 800,000 AF higher than last year and the north CVP “Big 3”, Trinity, Shasta and New Melones are 411,000 AF, 571,000 AF and 116,000 AF higher than on this same data last year, respectively.

Reservoir releases are consistent with past releases for this time of year; there are no particularly notable outliers although one could perhaps say that Keswick is releasing considerably more than the others in terms of their 15-year median releases. None of either Trinity, Shasta, New Melones, Folsom have made mandated “spills” to date.

Precipitation to date is still about 20-25% below average. But the combination of high storage and a modest snowpack help alleviate any serious concerns over accumulated precipitation to date. Average snow water equivalents (SWE) across the Northern, Central and Southern Sierra regions were 13.8” 12.9” and 9.8” or, 76%, 70% and 67% of normal for this date. Statewide, based on over 98 stations reporting, average SWE is 12.3” or 72% of normal for this date.

The next two months will be obviously important, but at this point, there is no reason to worry about the State’s water supply storage condition.

Prepared by Robert Shibatani Robert Shibatani, a physical hydrologist with over 35-years combined academic, legal, consulting and water advisory expertise, is an international expert witness on reservoir-operations, climate change hydrology, commercial flood damage litigation, and water supply development.  He is Managing Partner for The SHIBATANI GROUP International, a division of The SHIBATANI GROUP Inc. and resides in Sacramento, California.  robert@theshibatanigroup.com  

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