Edwards Aquifer Urban Hydrology Network

Comprehensive Surface-Water and Groundwater Monitoring

The Edwards Aquifer provides vital water resources for economic development, public and domestic water supplies, and ecosystem services for central Texas and the greater San Antonio area. City planners and water managers need high-quality water-resource information to make informed decisions for water availability, water quality, aquifer protection, and infrastructure growth. The U.S. Geological Survey (USGS) Urban Hydrology Network (UHN) encompasses monitoring of surface water and groundwater at appropriate spatial and temporal scales to provide insight to complex hydrologic issues in a region impacted by urbanization, population growth, and climate change.

The UHN provides high resolution, real-time, continuous monitoring data, augmented with periodic water-quality sampling, and deploying cutting-edge technologies to provide new information and tools for the public and stakeholders including:

  • Real-time continuous monitoring data, which provides insight into timescales of hydrologic change, such as from recharge events and drought effects.
  • Long-term data to evaluate water-quality trends in surface water and groundwater.
  • Integrated data to understand surface-water and groundwater interaction.

Click on image for larger view. From Musgrove and others, 2011.

Explore Local Surface-Water, Groundwater, and Water-Quality Data

Edwards Aquifer Urban Hydrology Interactive Map

data exploration graphic

Use the interactive mapper tool to find USGS hydrologic monitoring data from sites throughout the study area.

UHN Map Resources

The interactive mapping tool provides quick links to data for Surface Water, Spring, and Groundwater UHN sites.

UHN Reference Sites are shown with links to their organization's current data.

Associated Map Resources

USGS Real-time data within the study area.

National Weather Service real-time weather conditions.

Relevant Edwards Aquifer and hydrology layers.

Continuous Monitoring and Water-Quality Interactive Graphics

data exploration graphic

Compare continuous monitoring and water-quality data from UHN and other selected (reference) sites.

Summary of Findings

Changes in Nitrate Concentrations and Sources in Edwards Aquifer Groundwater

study area

The Edwards aquifer region is undergoing rapid growth, particularly in urban areas such as San Antonio and Austin. Such growth can increase anthropogenic sources of nitrate to groundwater. Nitrate is an important nutrient, but elevated concentrations may affect aquifer ecosystems. Additionally, consumption of drinking water with elevated nitrate concentrations may have adverse health effects.

Timescales and Drivers of Water-Quality Change in the Edwards Aquifer

study area

Groundwater quality changes over time. Long term monitoring of those changes helps groundwater resource managers understand and protect the aquifer. This study combined high-frequency monitoring and discrete sample collection of a range of geochemical constituents which enhances our ability to understand the timescales of groundwater quality change.

Continuous Monitoring Tracks Local Surface-Water and Groundwater Connections

study area

USGS "super sites" examine the dynamic connection between urban stormwater runoff and recharge to shallow groundwater of the Edwards aquifer. These sites monitor both streamflow and groundwater levels and are sites of water-quality sample collection during periods of groundwater recharge.

Urban and Rural Nitrate Sources to the Edwards Aquifer

study area

Groundwater nitrate data from continuous water-quality monitoring, combined with discrete water-quality samples from surface-water and groundwater, provide insight into nitrate contributions to the aquifer from rural and urban sources.

Contact Us

Kirstin Eller

San Antonio Water System



Douglas J. Schnoebelen, PhD

South Texas Branch Chief



Stephen P. Opsahl, PhD




MaryLynn Musgrove, PhD

Research Physical Scientist