Why is Groundwater Important?

• Drinking water for nearly 50% of US

• 98% of rural domestic supplies

• 35% of public supplies• 42% of irrigation for

agriculture• Sustains flow of

streams and rivers• Maintains aquatic

ecosystems

What Is Groundwater?

Contribution to Streamflow

54 StreamsRange 14-90%Average 52%

• Geology• Physiography• Climate

Runoff

Runoff

GW

GW

GW

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Groundwater and Drought

Groundwater and Drought:Statewide Monitoring

Why Measure Water Levels?“You can’t manage what you don’t

measure”

• Water level in a well is an indirect measure of the amount of water in the aquifer.

• Principal source of information on the hydrologic stress on the aquifer

• Provides the data necessary to – evaluate changes in the resource over time – develop models and forecast trends, and – design, implement, and monitor the

effectiveness of groundwater management programs

http://groundwaterwatch.usgs.gov/

Groundwater Networks

Existing Nationwide Coverage

GWRP Regional GW Availability

• Quantify current groundwater resources

• Evaluate how these resources have changed over time

• Provide tools to forecast system responses to stresses from future human and environmental uses.

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Regional Groundwater Availability Studies

Principal Aquifers of the US

Selected Priority Aquifers

Ongoing or Completed Regional Studies