1. Wastewater Discharges to the Barton/Onion Creek Watersheds Barton Springs/Edwards Aquifer Conservation District

2. Outline Recharge of the Edwards AquiferPotential Impacts to GroundwaterSupporting Evidence for Discharge ProhibitionSummary

3. Spring Contributing Zone Recharge Zone Artesian Zone Relatively Impermeable Younger Formations Edwards Limestones Relatively Impermeable Older Formations Artesian Spring Artesian Well Balcones Fault Zone Edwards Artesian Aquifer Typical Cross-Section of the Edwards Aquifer Region Land Surface Edwards Aquifer Graphic courtesy of Gregg A. Eckhardt

6. Evidence  The contributing streams above the recharge zone are no flow or low flow most of the time thus effluent discharges would dominate recharge most of the time.  Hill country streams are nutrient poor with very low assimilative capacity, sensitive to any nutrient inputs.  Studies confirm degradation (change in trophic status) would occur from a single permitted discharge under some conditions  The BS segment of the aquifer has limited ability to assimilate pollutants.  The BS segment is much smaller in size and by volume than the SA segment offering reduced opportunity for dilution of pollutants  Dye trace studies confirm direct connections of recharge from contributing watersheds to the Aquifer, public supply wells, and Barton Springs  Rapid transport of nutrient enriched recharge water would have undesirable effects on Barton Springs and its endangered species habitat.

8. Summary  All existing developments successfully manage wastewater with alternative disposal methods (TLAP, 210)  Not intended to be an obstacle to development  Promotes reuse of water via a properly sited and designed Land Application System  §311 and §213 currently do not provide adequate protection.  Should be in §311 to protect both contributing-zone stream quality and downstream recharge water quality  Needed to prevent cumulative impacts in the aquifer from multiple discharges and to preserve pristine hill country streams  Contributing Zone should be treated as an extension of the Recharge Zone for water quality protection.  Needed to preserve recharge water quality, protect public supply wells, the Barton Springs pool, and the endangered species habitat  Supported by the local political jurisdictions over essentially all of these watersheds (Travis Co., Hays Co., BSEACD, CoA, CoDS, others)