An intriguing paper from some folks at UT Austin, looking at the isotopic composition of water in Austin-area streams. Turns out that the natural source water in the area has very different strontium ratios from the imported municipal water brought in from their Colorado River:
In the more urbanized watersheds, Sr-isotope mass balance indicates that ~ 90% of base flow is composed of water from anthropogenic sources.
Where’s it coming from?
1) leakage from the sewage system, 2) leakage from the water supply system, or 3) irrigation (e.g. lawns and gardens).
Thanks to Kevin Anchukaitis for pointing me to the paper.