Surface Water

Rivers, lakes and streams. These are surface waters which are a primary source of water in Arizona. When it rains or snows, the precipitation either seeps into the ground or flows directly into a river or lake. Eventually, this runoff ends up flowing into the ocean. But not all the runoff ends up here. Some of it evaporates on its way downstream… thirsty wildlife also enjoy it… and some of the water is diverted and used by cities, towns and industries along the way.

When dams are built to store a river’s flow, a lake or reservoir is formed. These rivers, lakes, streams and reservoirs are vital to our everyday life. The main uses for this water include irrigation, producing electricity, cooling equipment, agriculture and of course…drinking water. Of course, this also includes cooking, cleaning, bathing and even recreational activities.

Ground Water & Recharge

Ground WaterOne of our most valuable resources is the water beneath our feet. Something you can’t see and may not even know is there. Ground water is the part of precipitation that seeps down through the soil until it reaches rock material that is saturated with water. Ground water slowly moves underground, generally at a downward angle (because of gravity), and may eventually seep into streams, lakes, and oceans. 

Most of the void spaces in the rocks below the water table are filled with water. But rocks have different porosity and permeability characteristics, which means that water does not move around the same way in all rocks. When water-bearing rocks readily transmit water to wells and springs, they are called aquifers. Wells can be drilled into the aquifers and water can be pumped out. Precipitation eventually adds water (recharge) into the porous rock of the aquifer. The rate of recharge is not the same for all aquifers, though, and that must be considered when pumping water from a well. Pumping too much water too fast draws down the water in the aquifer and eventually causes a well to yield less and less water and even run dry.

Ground water is an important natural resource, especially in those parts of the country that don’t have ample surface-water sources, such as the arid West. It provides about 38 percent of the water delivered by water departments for use in our homes, businesses, and industries and provides drinking water for the 99 percent of the rural population who supply their own water from their own wells.