Groundwater monitoring staff collect quarterly samples from six springs in the Barton Springs segment of the Edwards Aquifer: Parthenia in Barton Springs Pool, Eliza, Old Mill (Sunken Garden), Upper Barton, Backdoor and Cold.
The Barton Springs segment of the Edwards Aquifer (BSEA) is an important resource for the Austin area. It supplies drinking water to wells for numerous communities, provides habitat for endangered species, provides clean base flow to the Colorado River and supplies the City of Austin with part of its drinking water supply. Large rain events fill or "recharge" the aquifer, which feeds Barton Springs. Recharged water can begin discharging from Barton Springs in a matter of hours.