Drought In California - Again

California is remarkable vulnerable to the impact of climate change.  The state's agricultural economy depends on water that is accumulated during the winter rainy season.  The northern and central areas of the state are dependent on snowfall from winter storms that build a deep snow pack in the Sierra Nevada mountains.  The southern part of the state is nourished by some of that water, but also depends heavily on snow pack build up in the Rocky Mountains that feed into the Colorado River.  The forecast for both mountain ranges and the rivers their snow pack feeds is bleak. 

Climate change has shortened California's rainy season by a month since the 1960s.  

This year, the state saw a very delayed start to its annual rainy season, which is typically heaviest from January to March. Wildfires sparked as late as January. It’s a sign that the window of time where rainfall and snow can add to the state’s water reserves is shrinking, says John Abatzoglou, a climatology researcher at the University of California, Merced – and that window may be even narrower in the future.

Most of the state’s water comes from an astonishingly low number of precipitation events – just three to five winter storms do the work of building up the snowpack and filling reservoirs. That makes California uniquely vulnerable. “In years where you miss out on one or two of those, you’re probably going to struggle to get close to normal,” says Abatzoglou.

Without water California's Central Valley, the most prolific agricultural area in the nation will become a dust bowl. Agricultural interests in the valley have long since increased their water demands beyond what seasonal rains and even the state's extensive reservoir system can support.  Instead they have pumped so much water from underground aquifer that the entire central valley is sinking.

For decades, farmers have relentlessly pumped groundwater to irrigate their crops, draining thick, water-bearing clay layers deep underground. As the clays compress, roads, bridges, and irrigation canals have cracked, causing extensive and expensive damage. In 2014, when NASA scientists flew radar equipment over the California Aqueduct, a critical piece of water infrastructure, they found that one section had dipped 20 centimeters over 4 months... Excessive pumping also jeopardizes water quality, as pollutants accumulate within groundwater and the clays release arsenic. Worst of all, the persistent pumping means that, one day, aquifers might run out of usable water. 

Southern California's dependence on the Colorado River watershed will once again create incredible stress on water resources in the most populous region of the state.  Population growth in the seven western states that depend on the Colorado River combined with the expansion of agricultural activity in regions of historical water scarcity are generating substantial demands on a system that depends on the same weather patters that have diminished Northern California's rainy seasons.   

A sobering forecast released this week by the Bureau of Reclamation shows the federally owned Lake Mead and Lake Powell — the nation’s two largest reservoirs and critical storage for Colorado River water and its 40 million users — dipping near-record-low levels. If those levels continue dropping as expected, long-negotiated agreements reached by the seven Colorado River Basin states in 2019 will go into effect, with water deliveries curtailed to prevent the federal government from stepping in and making hard water cuts.

The Bureau of Reclamation’s quarterly report was dire, showing Lake Powell at 42% of capacity and downriver’s Lake Mead at 40% capacity. And there’s not much water coming.

Climate change did not take 2020 off due to Covid-19.