The worst drought in recorded history just got worse.

California's main source of surface water during the state's dry summer months is the remaining snow on its highest mountains. But it has officially melted. The snowpack levels, which hovered at around 7% to 15% of normal for this date in 2009, before the four-year drought began, are currently at 0%.

What does that look like?

Here's a map of the California snowpack on May 29, 2009:

And here's a map of the California snowpack on May 29, 2015:

There is still some snow left from stations that haven't yet reported and in the state's already-low reservoirs, as Eric Holthaus notes over at Slate, but still, this doesn't look good.

"This is essentially a worst-case scenario when it comes to California’s fragile water supply," writes Holthaus.