1. Surface water and Barton Springs What do we know? –After a storm –The rest of the time Current study objectives TCEQ – USGS study approach Additional research

2. Storm response: specific conductance Barton Springs discharge Barton Springs specific conductance Rainfall begins

3. Storm response: Atrazine Barton Springs discharge Atrazine in Barton Springs discharge

4. Non-storm conditions

5. 2005 Total Recharge: 3,050,000,000 ft 3 2006 Total Recharge: 125,000,000 ft 3 Proportion of recharge contributed by each creek: 2005 (wet) vs 2006 (dry)

6. Approach for current USGS- TCEQ nutrient study Routine sampling under range of bi-annual conditions –5 surface-water sites –2 ground-water sites –Main Barton Springs Event-based sampling for three storms –5 surface-water sites –Main Barton Springs

8. Analytes of interest: TCEQ Full suite of nutrients Major ions Trace elements (Sr, B, Br) Suspended sediment concentration E. coli

9. Additional analytes 65 Waste-water compounds –Fragrances –Pharmaceuticals –Surfactants N and O isotopes of nitrate Sr isotopes (U.T. doctoral student) Three storm events and a selected number of routine samples.

10. ~0.3 ft 3 /s ~24-hr intervals Barton Creek @ Lost Creek has higher SC (~713) than Barton Springs ~ 24-hr increase in SC ~ 12-hr lag Perturbations from rainfall, lowering the level of the pool for cleaning. Stream flow at Barton Creek Specific conductance at Barton Sp