The Save Our Springs Ordinance (SOS) was adopted in 1992 and differed from its predecessors because it became law by citizen initiative. Two ordinances worth noting preceded the SOS Ordinance: the Interim and Composite Ordinances. These ordinances addressed development in the Barton Springs Zone, which includes Barton Creek and the other creeks draining to, or crossing, the Edwards Aquifer recharge zone. Highlights of these ordinances included: the first requirements for non-degradation (based on stormwater discharge concentrations) and provisions that excluded variances unless a demonstrable improvement in water quality was shown. Variances, which made departures from an ordinance permissible, were a general feature of watershed ordinances up until this time.
The SOS Ordinance, applied throughout the Barton Springs Zone, required: non- degradation (based on total average annual loading), and lowered impervious cover to 15 percent NSA for all development in the recharge zone, 20 percent NSA for development in the Barton Creek portion of the contributing zone and 25 percent NSA for development in the remaining portions of the contributing zone in Williamson, Slaughter, Bear, Little Bear and Onion Creeks.