Episode 7: The Groundwater Pumping Problem. In spite of Arizona's success drawing groundwater out of our aquifers and recharging them to keep them usable, we still pump more out of the ground than we put back in many parts of the state. And our population continues to grow. Our wells and pumps do a tremendous job of bringing water to the surface for us to use, and that's great! But what is happening underground where we can't see? Well, as we extract water from an upper level or unconfined aquifer the groundwater levels go down. When a well is pumped, it draws from an area around the well. A similar thing happens when you drink a milkshake from a straw. So imagine if hundreds of wells are pumped in the same geographical area, their cumulative effect makes groundwater levels go down even faster.

The problem, though, comes when more water is withdrawn than is being recharged. Groundwater pumping can actually affect our rivers causing surface water to disappear into the ground. This lowering of the water table can remove water from the root zone of plants near rivers, leaving them unable to survive, which then affects the wildlife that depend on them. In fact, we can even measure the groundwater depletion from space using satellites. Outside of Active Management Areas, groundwater use in Arizona remains largely unregulated, and over pumping is lowering groundwater levels around the state, causing wells to go dry. When we don't balance what is extracted with what is replaced, land subsidence can occur.

When large amounts of groundwater have been withdrawn from certain types of rocks, the rock compacts because the water is partly responsible for holding the ground up. The rocks fall in on themselves causing the land to subside. Cracks called "fissure cracks" occur along the margins of the sunken area. In large areas, this can affect the foundation of everything from farmland to buildings. Currently, the Arizona Geological Survey is working in 26 earth fissure study areas, encompassing 1,400 square miles. And new fissures continue to form. And if that's not bad enough, subsidence causes the aquifer to compress, reducing the amount of water that it can hold.

As scary as this is, we are working toward the safe management of our aquifers in Arizona, an amount that serves the needs of our communities and natural systems, but not so much that we drastically lower the water level and cause subsidence. But how do we do that? Watch Episode 8 to learn about balancing the groundwater system.