Wednesday, February 08, 2017Register
 Edwards Surface Water Quality & Quantity


The figures below display the surface water quality data on bacteria, pH and dissolved oxygen (DO). Fecal coliform bacteria, E. coli and Enterococci (indicators of pathogens in surface water) were analyzed. A higher amount of bacteria in more developed areas is common due to stormwater runoff, which increases with the amount of impervious surfaces in an area. Bacteria can originate from waste by pets and livestock, aging or leaking sewage infrastructure, and aging or malfunctioning septic tanks. Point sources can also be a source of bacterial pathogens; water treatment plants can sometimes leak untreated sewage into waterways due to operating over capacity, aging infrastructure, sudden flood events or other reasons. Certain aquatic invertebrate species, such as the endangered Comal Springs Dryopid Beetle (Stygoparnus comalensis) , are extremely sensitive to changes in bacterial level pathogens in the water.


Declines in precipitation and aquifer water levels can cause many problems with surface water bodies as well. There is concern over lowered water levels in lakes, wetlands, and springs, reduced stream flow in river systems, and reduced spring flow due to changes in precipitation and aquifer water level. The figures  show stream gage flow data throughout the Edwards Aquifer recharge area, displaying average flow compared to recent years and the drought years of the 1950's. Yearly flows with maximum and minimum flows are shown as well. Dry periods impact the threatened and endangered species in the area that depend on the flowing waters for their unique habitat. Duration and severity of low flow periods will determine the extent of the ecosystem threat and recovery.


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