The Edwards Aquifer sustains some of the most iconic springs of Texas, including the two largest, Comal and San Marcos Springs. The aquifer is the primary freshwater source for the city
of San Antonio and supplies water to several other cities along the I-35 corridor. It also provides water for irrigated agriculture. Striking a constant balance between the needs of
people and ecosystems is an ongoing challenge, but the karst nature of the aquifer--which allows it to recharge quickly--has made it possible.
What does the Texas Water Explorer tell us about the Edwards Aquifer?
Water Quantity
Water Use by Sector - Over the last five years, 72% of Edwards Aquifer groundwater use has been for municipal purposes with most of the remaining use for irrigation.
Aquifer Levels - Water levels in 25% of the Edwards Aquifer monitoring wells we examined have declined during the period from their establishment until present; more recently
(since
the year 2000), 42% have declined and none have increased.
Groundwater-fed Baseflow - None of the three groundwater-fed rivers and streams in the Edwards Aquifer that we examined have experienced a decline in baseflow since 1994. Over the
full periods of available data (60-90 years) none have declined and none have increased.
Groundwater Pumping - Total estimated groundwater use in 2011 was 171% of total Modeled Available Groundwater (MAG) pumping limitations for the Edwards Aquifer. Pumping has
exceeded
the MAG pumping limitations for three of the five counties in the Edwards Aquifer.
Priority Conservation Areas - The Nature Conservancy has defined 16 priority areas for freshwater biodiversity conservation that are sustained, in part, by groundwater from the
Edwards Aquifer.
Value of Water in the Economy - The Edwards Aquifer is overlain by 10 Texas counties; six of those produce more than the statewide average of $75,651 in total sales per acre-foot
of
water use. Six have more than the statewide average of 0.68 employees per acre-feet of water used.
Endangered Species Act - All 10 of the counties over the Edwards Aquifer have at least one federally threatened or endangered freshwater species, meaning that water management
decisions in these counties must balance human water needs with endangered species conservation.
Groundwater Conservation Districts - One of 10 counties over the Edwards Aquifer is without groundwater conservation districts and is therefore without local regulation of
groundwater.
Urban Water Use Efficiency - Average total per capita water use by 16 cities overlying the Edwards Aquifer is 159 gallons per capita per day (GPCD), just above the statewide
average of 154 GPCD. Average residential water use is 98 GPCD, while the statewide average is 69 GPCD.
The average water loss rate for 60 public water supplies over the Edwards Aquifer that utilize groundwater is 16%, while the statewide average is 16%.
Irrigation Demand - Two of the 10 counties overlying the Edwards Aquifer use more than the statewide average of 1.66 acre-feet per acre of irrigated cropland.
