Acre-feet of water imported yearly into Boulder County through transbasin diversions from the Western Slope. The annual average was calculated using thirty-five years of data from 1962-1997.
How much water is in an acre-foot:
Most of the water consumed by Boulder County municipalities, industries and agriculture comes to us through the Colorado-Big Thompson (C-BT) project, the largest transmountain diversion in the state, which has been serving the county's water needs since 1957.
From an environmental standpoint, transbasin diversions are damaging uses of water. In Colorado, such diversions are almost always taken out at high elevations, removing good quality water from alpine or sub alpine ecosystems, dewatering cold water fisheries and causing a variety of adverse impacts throughout the basin.
For "importing" communities, such diversions are a measure of economic and environmental sustainability. Water appears to be an unlimited resource, but in fact, we are using more water than can be provided by our own watershed.
An average 67,000 acre-feet of water are imported annually from west of the Continental Divide.
About 75% of the water we import is used for agricultural purposes and the remaining 25% is used by municipal and industrial customers. This follows statewide water use trends. When the C-BT project first came on-line in the late 50s, about 98% of the diverted water went to agricultural users.
Today, the population of Boulder county is four times larger than it was back then, so a greater percentage of imported water now goes to municipal and industrial uses.