Visualizing Water – Slide 8

If we focus only on our use of blue water in the Colorado River Basin, we see that irrigated agriculture withdraws and consumes by far the most blue water in this basin, accounting for 60% of all withdrawals and 53% of all consumption. Urban uses such as domestic water supply, industrial uses, and electricity account for a smaller portion, but they still collectively consume about 20% of all blue water. About 25% of water consumed goes to exports out of the river basin to cities such as Denver and Los Angeles. Evaporation from large reservoirs such as Lake Powell and Lake Mead is responsible for 13% of all consumption in the basin.
As the previous diagram showed, the total withdrawals of over 30 BCM is considerably more than the annual blue water flow of around 24 BCM, and this diagram makes clear how that is possible. Almost three quarters of all the surface water is withdrawn by agriculture, but about a third of that is returned to rivers and lakes. It may be polluted by fertilizers, pesticides, and salts, but it is still available in the system for use by other activities like domestic use or electrical plant cooling.
The Colorado River Basin is an extreme case, and it demonstrates well the importance of concepts like WITHDRAWALS and CONSUMPTION. The Colorado is a “water scarce” river basin because we consume so much of the available water.
One of our greatest challenges is finding ways to deliver the same quality of goods and services in the world’s water-scarce river basins without consuming so much of the valuable blue water. Thankfully, there is plenty of technology and sound approaches available to help us reduce our consumption. We can make improvements in every way that we use water, but because of the volume of water consumed in agriculture, we need to pay particular attention to ‘growing more crops with less drops.”