OKLAHOMA CITY -- The High Plains Aquifer, an underground water supply that underlies parts of eight states, including Colorado, could be depleted faster than expected.

That is according to a recent U.S. Geological Survey study.

The aquifer is being replenished at a lower rate than scientists previously thought.

In addition to Colorado, the the aquifer system underlies 174,000 square miles in parts of Wyoming, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota and Texas.

Approximately 20 percent of the irrigated land in the United States is in the High Plains and about 30 percent of the ground water used for irrigation in the U.S. is pumped from the High Plains aquifer.

The High Plains aquifer is the most intensely pumped aquifer in the United States, according to water experts.

According to the USGS, it is impossible to predict when the aquifer will be drawn below a useful level because it's impossible to predict future pumping costs, crop prices and advances in technology.