Bay Area Water Outlook: Underground Storage to the Rescue

Recharge ponds in Campbell (Mercury photo)

We've written before how the replenishment of underground aquifers is a relatively low-cost alternative solution to California's failure to build more reservoirs.

It may take years for the Central Valley to recover, but there is good news already about groundwater levels in the Bay Area. [bold added]

Groundwater provides 40% of the water supply for 2 million people in Santa Clara County. Following more than a dozen major atmospheric river storms this winter, the main water table in the county has risen 35 feet since last June — and is up 51 feet since the most extreme part of the drought in September 2021 — returning to pre-drought levels. The county’s main groundwater basin is now about 90% full.

...Readings taken two weeks ago show that groundwater is just 64 feet below the surface at the district’s main monitoring well in San Jose near the corner of Hamilton and Leigh avenues. That’s the highest level ever recorded since readings began there in 1936.

Similar rebounds have occurred in wells in Sunnyvale, Milpitas and Morgan Hill, where the main index well came up 50 feet since September of 2021 and is now at its highest level in five years.

A similar trend has unfolded at the Alameda County Water District, which provides water to 345,000 people in Fremont, Newark and Union City.

There, the water table has risen 13 feet since Dec. 31 at the Niles Cone Groundwater Basin, which provides 40% of the district’s supplies.

On a State-wide level recovery is less robust:

But some clues are emerging. Of 3,400 wells monitored by the State Department of Water Resources where measurements were taken this spring, 35% showed groundwater increases of at least 5 feet — however, 59% showed no change and 6% showed a decrease when compared with levels a year ago.

Regardless, California's water outlook is much better than it was a year ago.

This year's reprieve should not cause reservoir construction to slow, but historical performance would not make that a safe bet.