Edwards Aquifer recharge zone landcover changes 

This animation shows landcover changes within the Edwards Aquifer recharge zone in northern Bexar County. The area shown extends from SH 16 (Bandera Road) on the west to near Green Mountain Road on the east. It is the most heavily impacted area within the City of San Antonio's jurisdiction. These changes occurred over a 5-year period between 2001 and 2006.

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An alarming increase in urbanization, and decreases in open space and tree cover, were captured in images from the Landsat satellite. These images are from the National Land Cover Dataset which was developed by the Multi-Resolution Land Characteristics Consortium, a group of federal agencies.

Between 2001 and 2006, the following landcover changes were measured over the portion of the recharge zone within the City of San Antonio's jurisdiction (City limits & ETJ):

• 17% of its open space/grasslands & tree canopy were destroyed
• Tree canopy change: -5%
• Open space/grasslands change: -12%
• Urban areas change: +38%
• Bare areas change: +108%

Such large losses of open space and trees in such a short period are troubling. If this trend continues, impervious cover will likely reach levels known to cause water quality degradation in a matter of years, not decades.

San Antonio recently commissioned an Urban Ecosystem Analysis to develop tree canopy goals for this region. The report, published in May, 2009, recommended 55% tree canopy cover over the aquifer recharge and transition zones.

It is clear that the city's tree ordinance must be revised to stem this rapid tree canopy loss. Unfortunately, the revisions which have been proposed do not provide for achieving the 55% goal. Therefore, it is important for the community to contact City Council members and insist on an ordinance that protects their primary source of drinking water.