Current water law is designed to protect the property rights of the main water users that existed when the Groundwater Management Act was passed in 1980. These are cities, mines and a few other industries, and agriculture. This graphic shows the water uses and sources within the Tucson Active Management Area, which covers most of Eastern Pima County, and small parts of Santa Cruz and Pinal Counties.
One important thing to note is that current water planning and law doesn’t consider rain, even though this equals the total of both CAP and Net Natural Recharge. This is because no one (currently) claims to own the rain, so it is not currently regulated.
The biggest consumers of rain are:
- Water that runs down the streets until it evaporates (roughly 140,000 acre-feet per year)
- Water that falls on decorative landscaping (over 50,000 acre-feed per year). Locally produced food probably amounts to less than 2% of whatever we grow in Tucson.
What would happen, if we lose our CAP allotment? This is not eminent, at least for municipal and industrial users. But resent research shows that the entire Southwest has consumed 3 times as much groundwater as we have drawn down Lake Mead and Lake Powell.
Here is what Tucson’s water picture looks like, if we do lose CAP in about 7 years.