Aquifers / Groundwater

What Is an Aquifer

An aquifer is an underground body of permeable rock that contains or transmits groundwater. In this case permeable means that they have openings where liquids and gases can pass through. Sedimentary rock such as sandstone, as well as sand and gravel, are examples of rock with water-bearing potential. Aquifers typically fill with water from rain or melted snow that drains into the ground. The water moves downward until it meets less permeable rock.
Aquifer Example
Aquifers act as reservoirs for groundwater and wells drilled into aquifers provide water for drinking, agriculture, and industrial uses. Aquifers can dry up when people drain them faster than nature can refill them. Because aquifers fill with water that drains from the surface of the Earth, they can be contaminated by any chemical or toxic substance found on the surface.

There are two types of aquifers. An unconfined aquifer is covered by permeable rock and can receive water from the surface. The water table of an unconfined aquifer rises or falls depending on the amount of water entering and leaving the aquifer. It is only partly filled with water.

In contrast, a confined aquifer lies between two layers of less permeable rocks and is filled with water. Water trickles down through cracks in the upper layer of less permeable rock, a nearby water source, such as an underground river or lake, or a nearby unconfined aquifer. An artesian well is a type of confined aquifer that flows upward to the Earth's surface without the need for pumping. The artesian well sits below the water table at the bottom of U-shaped aquifers. Pressure from water in the long sides of the aquifer pushes the water up the well shaft.

Spokane Valley-Rathdrum Prairie Aquifer

The source of drinking water for over 500,000 people, the Spokane Valley-Rathdrum Prairie (SVRP) Aquifer is a natural treasure of North Idaho and Eastern Washington.

You can also visit the County's Groundwater Monitoring Program web page for current water quality and quantity information.