Dec/Jan Storms Push CA Precipitation To 1.7X Annual Average, No Impact On Central Valley Groundwater

[hatrack]

The three years since 2020 have been the driest in California in more than a century, with 35 per cent of the state under extreme drought conditions and more than 80 per cent under severe drought conditions by mid-December, according to the National Integrated Drought Information System (NIDIS). With the storms finished as of 19 January, no part of the state was under extreme drought and the portion under severe drought had shrunk in half, according to the NIDIS. Nearly all of the state remained under moderate drought conditions, however.

Jeanine Jones at the California Department of Water Resources says the NIDIS classification system is based on non-irrigated Midwestern agriculture so doesn’t accurately reflect California’s heavily managed water system or snowpack. But she says the storms have improved drought conditions, with total precipitation this year now up to 167 per cent of the annual average.

That water has brought the majority of the state’s major water supply reservoirs above average for this time of year, though these are kept around half full for flood control purposes during the current wet season. At three California reservoirs, managers are testing ways to rely on improved weather forecasts to safely store more water, says Jones.

EDIT

Things are more complicated when it comes to the state’s groundwater, which has seen huge losses from a combination of drought and a century of over-pumping. “One year, no matter how wet, is not going to recharge those groundwater basins,” says Jones. There are numerous projects underway to capture more water from storms to recharge those aquifers, but even large-scale improvements probably won’t be enough to stop some farmland from being taken out of production to balance groundwater budgets, as has been mandated by the state, says Daniel Mountjoy at Sustainable Conservation, an environmental nonprofit in San Francisco.

EDIT

https://climatecrocks.com/2023/01/31/rains-not-enough-to-recharge-colorado-river-or-californias-groundwater/#more-82501

[hunter]

1. Many of these groundwater basins have collapsed and will never hold as much water as they once did.