Water use in the Denver area is actually quite complicated. Changes in the demand for groundwater for various uses, addition of surface water sources to the water supply, and conservation measures all led to decreases in the amount of water being discharged from the Arapahoe aquifer from 1960 to 1990.

So how many people can the aquifer support? In reality, most people do not depend solely on water from the aquifer. A combination of surface water and groundwater is used to support the population. Also, variations throughout the huge extent of the aquifer make it difficult to estimate the total volume of water humans could actually pump from it. Over time, variations in climate, population growth, water use, and other variables will also alter the actual length of time that the aquifer can support people's water needs.

In order to come up with an estimate of the number of people an aquifer could support, some assumptions must be made. Use the assumed values below, or come up with your own to calculate an estimate that answers the investigation question.

10. Calculate an estimate of the number of people who could get all the water they would need all their lives from the Denver Basin aquifer system. Assume that:

The aquifer contains 15 trillion gallons of water.
People use 150 gallons of water per person per day.
Humans live eighty years.