It depends on which water you mean. The lakes that supply the city's tap water, the soil across the county, and the aquifer under Barton Springs are measured separately, and they don't always agree.
One acre-foot ≈ 325,851 gallons.
100% abnormally dry (D0) · 100% moderate drought (D1) · 79% severe drought (D2). Each level includes the more severe ones inside it.
Source: US Drought Monitor, produced by NDMC, USDA and NOAA.
Barton Springs flow
20 cfs 10-day average
Lovelady well level
455.3 ft above sea level, 10-day average
Triggers from the district's published methodology (Smith, Hunt & Holland 2013, as amended by later declarations). Official stages are declared by the district board and can lag the measurements: current declared stage.
Austin has watering rules year-round, drought or not. The city's baseline Conservation Stage limits outdoor watering to set days and hours, and deeper stages tighten those limits. Check the current schedule before you water.