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SJ County in severe drought
New melones
New Melones Reservoir is at 25 percent of capacity for this time of year.

All of San Joaquin and Stanislaus counties are now in severe drought.

So is most of Merced County.

And the three watersheds in the Central Sierra that the Northern San Joaquin Valley counties rely on to meet urban and agricultural needs are in moderate drought.

Topping that, all three of the Central Sierra reservoirs that do the heavy lifting for water storage for the Northern San Joaquin Valley as of Tuesday were all significantly below average capacity for Dec. 8. It includes New Melones — critical to water supplies for the South San Joaquin Irrigation District along with the cities of Manteca, Lathrop, and Tracy — that is at 25 percent of normal for this time of year.

And while it is too early to tell whether 2021 will become a drought year given we’re just two months into the new water year that started Oct. 1, the conditions are being monitored by those responsible for the region’s water supplies.

“It’s a little early to tell with two months into the water year if we’re going to be in the clear or have issues,” noted SSJID general manager Peter Rietkerk.

Making the 2021 water year dicey is the developing weather phenomenon known as La Niña that often can historically plunge much of California into the grips of a full-blown drought.

Various models suggest another drier than normal year at the very least.

Based on the 1988 water agreement with the Bureau of Reclamation, the SSJID and Tri-Dam partner Oakdale Irrigation District, have the rights to the first 600,000 acre feet of water they split 50-50 that flows into New Melones Reservoir after Oct. 1.

Snowfall — the bulk that typically occurs between December and mid-March — seals the water supply fate not just for a large swath of the 209 but also much of the state given almost 60 percent of the water California uses annually comes from the Sierra snowpack.

A weak snowpack also will impact SSJID in terms of their share of wholesale electricity sales from the Tri-Dam Project.

The two major Tri-Dam reservoirs are in fairly good shape. Donnells with a capacity of 64,320 acre feet of water is at 29 percent of capacity but is at 106 percent of what is normal for Dec. 8. Beardsley with a 97,800 percent capacity is 33 percent filled which is 80 percent of normal for this time of year.

Keep in mind, though, that the 63,000 acre feet currently in the two reservoirs is about a fourth of what SSJID uses in a year. That doesn’t account for fish flows and such.

While it is highly unlikely that the Central Sierra will go without snow storms in the coming months, the Tri-Dam storage coupled with New Melones is on the low side.

Lathrop and Tracy mix SSJID surface water with other sources year round. Both access groundwater while Tracy also taps into the state water supplies from a nearby canal.

Manteca has their system set up so they can cease pumping ground water during the winter. That reduces depletion of the aquifer plus slashes electrical costs associated with pumping. That said underground water supplies are impacted by drought conditions as well. Not only does use soar but the aquifers aren’t being replenished.

Statewide based on the United States Department of Agriculture Drought Monitor 96.5 percent of the state is abnormally dry, 75.03 percent is in moderate drought, 48.19 percent is in severe drought, and 19.36 percent is in extreme drought.


To contact Dennis Wyatt, email