By Rob Davis at voiceofsandiego.org:
Lake Mead, the vital Colorado River reservoir outside Las Vegas, hit a record low Sunday, The New York Times reports. The reservoir is the lowest it’s been since being filled in the late 1930s, just 39 percent full.
Millions of people — San Diegans included — rely on the reservoir’s water.
So what does its drop mean here?
In the short term, nothing. It doesn’t have any impact on San Diego’s supply even though we relied on the river for 61 percent of our water in 2009. But it does send a bad signal that the river supplying the Southwest’s lifeblood is continuing to face pressure — a pressure that scientists say is growing as the climate warms.
If the lake continues dropping, it will first cause problems for cities in Arizona and Nevada before San Diego. Those states hold lower-priority rights to Colorado River water than California does.
Right now, Lake Mead is filled to 1,083 feet above sea level. If it drops to 1,075 feet, the U.S. Bureau of Reclamation will declare a shortage and implement cuts the seven Colorado River states agreed to in 2007. Those cuts hit Arizona and Nevada — not California.
The cuts would stay in place until the reservoir hits 1,025 feet. Then the shortage is renegotiated and becomes an issue that could affect California.
The Bureau of Reclamation’s current plan for the coming year calls for an increase of up to 40 percent in the amount of water delivered to Lake Mead from Lake Powell, the big reservoir upstream, a step that could help equalize the amount of water in each reservoir and possibly avoid triggering the shortage declaration.