In Colorado River Basin, Groundwater Is Disappearing Much Faster than Lake Mead [View all]

[GliderGuider]

In Colorado River Basin, Groundwater Is Disappearing Much Faster than Lake Mead

The mineral-stained canyon walls and the plunging water levels at Lake Mead, the nation’s largest reservoir, are the most visible signs of the driest 14-year period in the Colorado River Basin’s historical record.

But the receding shorelines at the Basin’s major reservoirs — including Lake Mead, which fell to a record-low level this month, and Lake Powell, the second largest reservoir on the Colorado, 290 kilometers (180 miles) upstream from Mead — are an insignificant hydrological change compared to the monumental disruption taking place underground.

Satellite data show that in the last nine years, as a powerful drought held fast and river flows plummeted, the majority of the freshwater losses in the Basin — nearly 80 percent — came from water pumped out of aquifers.

The decrease in groundwater reserves is a volume of water equivalent to one and a half times the amount held in a full Lake Mead, according to a study published today in the journal Geophysical Research Letters.

“We didn’t think it would be this bad,” said Stephanie Castle, a researcher at the University of California, Irvine, and the study’s lead author. “Basin-wide groundwater losses are not well documented. The number was shocking.”