Flooding in the highland lakes region has caused the City of Austin to issue a boil water and emergency conservation notice for Austin Water customers on Oct. 22, 2018. Several groundwater users have contacted the District to ask if they should be concerned about groundwater water quality. There is no indication that regional groundwater quality has been negatively impacted by the recent rain events. The major floods have been outside the District’s recharge and contributing zones; however, well owners should pay close attention to any changes in their well water.
During rain events, wells in karst aquifers (like the Edwards & Trinity Aquifers) can see quick recharge, just as the Highland Lakes have seen. Runoff can wash sediments and contaminants into the groundwater system. Occasionally, well owners notice a change in taste, odor or appearance after rains—this is an indicator that the well is directly connected to the surface through caves or fractures common in karst aquifers. If groundwater users ever notice a change in taste, odor or appearance, you can boil the water before drinking or use bottled water to be cautious. If you have a question about your water quality, you can take a sample to an area lab to have it analyzed. Common treatment systems that take care of bacteria (the most common surface contaminant) use either chlorination, ultraviolet light, or reverse osmosis for their drinking water.
The silt, sediment, and other particulates in the Colorado River are so high that surface water systems’ filters and treatment equipment are having trouble keeping up with demand. While Edwards and Trinity Aquifer wells are not tapped into the Colorado River, those same recent rain events may have washed surface sediments and contaminants into the groundwater.
There’s a good overview of wells and major rainfall events here: https://bseacd.org/2015/11/wells-and-major-rainfall-events/
- Aquifer District Well Owner Resources page (with sampling instructions and water quality lab contact information)
- City of Austin Boil Water & Mandatory Water Conservation Notice (10/22/2018)
- Texas Well Owner Network Fact Sheet, Solving Water Quality Problems in the Home (with table of treatment systems and what they address)