California’s three-year drought just went from bad to dreadful. In the course of the last week, the crimson expanse of “exceptional drought” grew to engulf the northern part of the state.
The chart above shows the drought's progression as reported today by the U.S. Drought Monitor. Archived maps show the end of July for each year since 2011.
All of California is in "severe drought" (shown in orange), and 82 percent is rated “extreme drought” (in red). The agency’s highest drought rating -- “exceptional drought” (crimson) -- now covers 58 percent of the state, up from 36 percent a week ago. Exceptional drought is marked by crop and pasture loss and water shortages that fall within the top two percentiles of the drought indicators.
The water reserves in California’s topsoil and subsoil are nearly depleted, and 70 percent of the state’s pastures are now rated “very poor to poor,” according to the USDA.
Reservoir levels are dropping, and groundwater is being drained from the state as farms and cities pull from difficult-to-replenish underground caches. The state’s 154 reservoirs are at 60 percent of the historical average, or 17.3 million acre feet lower than they should be. That’s more than a year’s supply of water gone missing.
It’s not the worst drought California has ever seen -- in 1977, the state’s water storage was at 41 percent of the historical average -- but conditions are still getting worse.
The Colorado River Basin, which feeds California and six other states, is “the most over-allocated river system in the world,” according to a study of satellite records released last week that shocked scientists with the magnitude of water loss.
Since 2004, the basin lost nearly 53 million acre feet of freshwater. That’s enough to submerge New York City beneath 344 feet of water.
More from Tom Randall:
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- Latest State of the Climate: Yup, Still Getting Hotter
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