A new study released Wednesday forecasts a shortage of more than 3 million acre-foot in Colorado River water by 2060.

Demand for water will increase from an average 15.3 million acre-feet annually to between 18.1 million to 20.4 million acre-feet, according to the Colorado River Basin Water Supply and Demand Study. An acre-foot is the amount of water required to supply 2½ households for one year.

"It's fair to say that the demand has already outstripped supplies within the lower basin," said Ted Kowalski, section chief for the Colorado Water Conservation Board who worked on the study.

Kowalski explained that demand in states in the lower river basin exceeds their entitlement to the river's water under the 1922 Colorado River Compact and Law of the River.

The nearly three-year study began in January 2010 as a joint effort of the U.S. Bureau of Reclamation and representatives of the Colorado River basin states.

A population in the basin states that could double to 35 million by 2060 will contribute to the increased water use and supply imbalance, Kowalski said. Additionally, climate change could lead to greater agricultural water consumption. Growing energy use also could stress