Post by L Roebuck on Aug 16, 2006 16:41:46 GMT -5
Guide to S.A. — Aquifer supplies 1.7 million with water
Web Posted: 08/16/2006 03:45 PM CDT
San Antonio Express-News
The Edwards Aquifer is a raised and faulted ancient seabed that is one of the most productive aquifers in the country.
Stretching 175 miles from Brackettville on the west to Buda on the east, the limestone formation has experienced millions of years of water flow and developed sinkholes, caves, conduits and fissures that allow it to hold and transmit water somewhat like an underground river.
The aquifer provides water for an estimated 1.7 million people — farmers, industries and residents of cities that live atop it and even those who live far downstream on the Guadalupe River. During drought, Edwards Aquifer springs provide about two-thirds of that major river's flow 100 miles downstream.
The exposed part of the formation — the edge of the Texas Hill Country that starts in northern San Antonio and is known as the Balcones Escarpment — is called the recharge zone. Ranging from five to 30 miles wide and stretching the length of the aquifer, it rapidly accepts rainfall runoff and the flows of streams that run across it.
The formation plunges underground beneath San Antonio and the water is under artesian pressure. That means that many wells drilled into it don't need pumps for water to flow out and into pipes. The water is so clean that it's only lightly filtered and has chlorine added as a disinfectant before it's piped to customers' homes.
The US Geological Survey has concluded that the Edwards contains 45 million acre-feet of fresh water, but permitted annual pumping is limited to 450,000 acre-feet. Long-term annual average recharge is 719,200 acre-feet, although the past 20 years have been much wetter than normal. What's not pumped flows from springs.
Comal Springs in New Braunfels and San Marcos Springs support eight federally protected aquatic species that are found nowhere else.
Although the Edwards Aquifer is not in danger of running out of water, the requirement to keep the springs flowing for the species and for downstream needs means that area drought plans are implemented when the aquifer's level in San Antonio falls to 650 feet above sea level.
— Jerry Needham
San Antonio Express-News publish date Aug. 20, 2006
Article: San Antonio Express-News
Web Posted: 08/16/2006 03:45 PM CDT
San Antonio Express-News
The Edwards Aquifer is a raised and faulted ancient seabed that is one of the most productive aquifers in the country.
Stretching 175 miles from Brackettville on the west to Buda on the east, the limestone formation has experienced millions of years of water flow and developed sinkholes, caves, conduits and fissures that allow it to hold and transmit water somewhat like an underground river.
The aquifer provides water for an estimated 1.7 million people — farmers, industries and residents of cities that live atop it and even those who live far downstream on the Guadalupe River. During drought, Edwards Aquifer springs provide about two-thirds of that major river's flow 100 miles downstream.
The exposed part of the formation — the edge of the Texas Hill Country that starts in northern San Antonio and is known as the Balcones Escarpment — is called the recharge zone. Ranging from five to 30 miles wide and stretching the length of the aquifer, it rapidly accepts rainfall runoff and the flows of streams that run across it.
The formation plunges underground beneath San Antonio and the water is under artesian pressure. That means that many wells drilled into it don't need pumps for water to flow out and into pipes. The water is so clean that it's only lightly filtered and has chlorine added as a disinfectant before it's piped to customers' homes.
The US Geological Survey has concluded that the Edwards contains 45 million acre-feet of fresh water, but permitted annual pumping is limited to 450,000 acre-feet. Long-term annual average recharge is 719,200 acre-feet, although the past 20 years have been much wetter than normal. What's not pumped flows from springs.
Comal Springs in New Braunfels and San Marcos Springs support eight federally protected aquatic species that are found nowhere else.
Although the Edwards Aquifer is not in danger of running out of water, the requirement to keep the springs flowing for the species and for downstream needs means that area drought plans are implemented when the aquifer's level in San Antonio falls to 650 feet above sea level.
— Jerry Needham
San Antonio Express-News publish date Aug. 20, 2006
Article: San Antonio Express-News
