20260715-002, History of Watershed Protection Ordinances Presentation — original pdf

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The History of Austin’s Watershed Protection Ordinances Austin Watershed Protection | 07/15/2026 Presentation Outline  Major, historic Austin moments  The impact of geography, weather, demography, and politics  Key watershed protection regulations  Austin’s major watershed ordinances  Concluding thoughts 4 4 Geography: Edwards Plateau Barton Creek looking toward downtown 5 Geography: Blackland Prairie Gilleland Creek at SH 130 Crossing 6 Lake Travis Lake Austin Lady Bird Lake Colorado River Welcome to AUSTIN 7 Rapid Population Growth  11th largest city in the U.S.  22% population change 2010-18  2nd highest rate in top 50 U.S. cities  But recently slowing in Austin  Current estimated population (2025)  1.03 million in full-purpose limits  2.62 million in the 5-county MSA  Development required to keep pace MSA = Metropolitan Statistical Area Austin Population 1940-2025 + Projection to 2050 1,400,000 1,200,000 1,000,000 800,000 600,000 400,000 200,000 n o i t a l u p o P Projected Past 0 1920 1940 1960 1980 2000 2020 2040 2060 Year Source: https://demographics-austin.hub.arcgis.com/... 8 Citizen Involvement Highly aware & educated community Politically & socially active community 9 State Involvement Highly aware & educated community Politically & socially active community 10 Flash Flood Alley The Central Texas Hill Country is the most flash-flood-prone area in North America “Texas is a land of perennial drought, broken by the occasional devastating flood.” Unnamed National Weather Service meteorologist, 1927 Pontoon Bridge, 1869 Destroyed by flood < 1 year after built 12 Original Austin Dam Completed 1891 13 Original Austin Dam Destroyed 1900 14 2nd Dam begun, 1912… Damaged in construction by two large floods… never completely built 15 1935 Flood 16 1935 Flood 17 Construction of the Highland Lakes 18 Lake Travis at Mansfield Dam, built 1942 LCRA photo 19 Tom Miller Dam, built 1940 LCRA photo 20 1981 Memorial Day Flood 21 Barton Creek Square Mall Barton Springs: ~ 2 miles downstream 22 https://www.youtube.com/watch?v=JQNrdLTvlFc 23 Eastern Headwaters Creeks 24 2013 Onion Creek Flood 25 Key Watershed Protection Regulations (from ordinances)  Watershed classification (impervious cover and more)  Impervious cover limits  Floodplain restrictions/prohibitions  Stream setbacks/buffers  Erosion hazard zone (EHZ) requirements  No adverse impact  flood detention ponds  Water quality controls (“ponds”) 26 26 Key Watershed Protection Regulations (from ordinances, continued)  Erosion & sedimentation controls  Critical Environmental Feature (CEF) setbacks/buffers  Steep slope protections  Cut & fill limits  Floodplain modification requirements  Tree, soil & plant protections  Landscape requirements 27 27 Watershed Classifications  Geographically specific protections for five different areas  Urban and Suburban in the central and eastern “Desired Development Zone”  Barton Springs Zone, Water Supply Suburban and Water Supply Rural in the western “Drinking Water Protection Zone” Water Supply Suburban (11.6% of area) Water Supply Rural (9.5% of area) Urban (14.8% of area) Suburban (48.6% of area) Barton Springs Zone (15.6% of area) Area pct = pct of total parcel area within City Limits 28 Overall Objectives • Protect Sensitive Features • Minimize Site Disturbance • Manage Stormwater Runoff 29 Floodplain Updated in 2019 with the Atlas-14 rainfall study 30 Creek Buffers * Drinking Water Protection Zone only 31 Erosion Hazard Zone 100 feet wide review buffer on each side of the creek centerline 32 Steep Slopes 15 to 25% 25 to 35% Greater than 35% 33 Impervious Cover Limits by Watershed Classification Water Supply Suburban 40%+ 20%+ Water Supply Rural Urban 45 - 95% 15 - 25% Suburban 50 - 80%+ Barton Springs Zone 37 Impervious Cover Existing Pct. by Watershed Classification (parcels within City Limits) Water Supply Suburban Water Supply Rural Barton Springs Zone 20.5% 11.0% Urban 50.9% 18.7% Suburban 26.1% 38 Impervious Cover 60% in Uplands (NSA)* 30% in WQTZ* 0% in CWQZ * Varies with watershed classification and zoning / land use type NSA = Net Site Area in Drinking Water Protection Zone; CWQZ = Critical Water Quality Zone; WQTZ = Water Quality Transition Zone 39 Critical Environmental Features Bluff Spring Bluff CEFs include bluffs, canyon rimrocks, caves, sinkholes, springs, and wetlands 40 Tree Protection 42” Live Oak Tree regulations only apply within the zoning jurisdiction (City Limits) 41 Cut and Fill Limits 4 feet max cut & fill (except Urban) Administrative variances for some cases 42 Erosion & Sedimentation Controls Limits of Construction 43 Structural Stormwater Controls (a.k.a. “Ponds”) Water Quality Pond Water Quality Pond Note: This example project participated in a Regional Stormwater Management Program (RSMP) in lieu of providing an onsite flood detention pond 44 Austin’s Major Watershed Ordinances 1974 Waterway Ordinance Lake Austin/Barton/Williamson Ordinances 100-Year Floodplain Ordinance Comprehensive Watersheds Ordinance (CWO) 1980 1983 1986 1992 Save Our Springs (SOS) Ordinance 2013 2019 Watershed Protection Ordinance (WPO) Atlas 14 Floodplains Ordinance Honorable Mention: - 1982 Landscape Ordinance - 1983 Tree Ordinance - 1991 Urban Watershed Ordinance (UWO) - 1911 Maximum Flood Ordinance 45 Austin’s Major Watershed Ordinances 1974 Natural creeks, 25-year floodplains, flood detention Creek buffers, IC limits, WQ controls, E&S controls & more* 100-year floodplains (FPs) Citywide watershed protections (almost) 1980 1983 1986 1992 Non-degradation water quality protections 2013 2019 Eastern headwaters, erosion hazard zones & more Updated 100-year floodplains and 2-ft freeboard Honorable Mention: - 1982 Parking lot aesthetics & natural function - 1983 Tree preservation - 1991 Citywide watershed protections - 1911 Do something about flooding! * E&S = Erosion & Sedimentation IC = Impervious Cover WQ = Water Quality 46 Major Milestones in Austin’s Watershed History Lake Austin, Barton & Williamson Creek Ordinances Comprehensive Watersheds Ordinance (CWO) Watershed Protection Master Plan Residential Infill Ordinance Waterway Ordinance Floodplain Ordinance Save Our Springs Ordinance (SOS) Watershed Protection Ordinance (WPO) 1911 1974 1977 1980 1981 1983 1986 1991 92 1996 1998 2001 2013 2019 22 25 Drainage Criteria Manual Drainage Fee Established Urban Watersheds Ordinance (UWO) + Drainage Utility created Maximum Flood Ordinance Balcones Canyonlands Conservation Plan (BCCP) Permit & Water Quality Protection Lands (WQPL) Atlas 14 floodplain ordinance Green Stormwater Infrastructure 47 Major Milestones in Austin’s Watershed History Austin Tomorrow Comprehensive Plan (1979) Creek buffers, Water quality ponds, Impervious cover limits Citywide watershed protections Systematic watershed protection approach; call for improved regs Calibrate regs to small- scaled residential infill Natural waterways, 25-yr floodplain restrictions & flood detention 100-yr floodplain restrictions Non-degradation WQ standard Eastern streams need better protection 1974 75 77 1980 1981 1983 1986 1991 92 1996 1998 2001 2013 2015 2019 22 25 FEMA NFIP: floodplain maps begin CIP funding source Systematic, adequate drainage infrastructure Sustainable funding source Direct land protection Major Flood Rapid Barton Springs Zone Development 2008-15 Drought Expand floodplains, increase bldg. elevations due to greater flood risk Green water quality controls required 48 Concluding Thoughts  Watershed protection is a relatively young, and still evolving, practice  Many core regulatory watershed protections are already in place  An ounce of prevention is worth a pound of cure… and difficult after  Still fine tuning: new era of infill, redevelopment, and static boundaries Two initiatives in progress: unstable slopes & greenfield drainage standard   Community attention and focus changes over time  State and national interactions are a wild card  How to adapt our regulations to climate change?  Rain to River Strategic Plan: a guide to effective choices 49 Questions? Matt Hollon Regulatory Policy Analyst Matt.Hollon@austintexas.gov 512-974-2238 Comments? 50