20260916-003, Dog's Head Update Presentation — original pdf

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Dog’s Head Update to Environmental Commission Liz Johnston, Environmental Officer Watershed Protection Department | September 16, 2026 Dog’s Head Update This presentation is focused on items primarily related to Austin Watershed Protection and will provide an overview on the following topics: ▪ Site Context ▪ May Council action ▪ July Council action ▪ Regulatory Comparison Table ▪ Floodplain Update ▪ Next Steps, including brief explanation of a regulatory plan ▪ Q&A 2 Property Information ▪ Annexed into Full Purpose May 2026 ▪ District 3 & 2-mile ETJ ▪ Colorado River & Carson Creek ▪ Bounded by Colorado River to north & east ▪ Previously used as sand/gravel mining operations Colorado River Watershed Carson Creek Watershed Watershed boundaries and creek centerlines Council District 3 boundaries. Information from Property Profile 3 US 183 Longhorn Dam Colorado River SH 71 Aerial imagery courtesy of NearMaps Dog’s Head Current and Historic Aerial Images 1940 2017 2026 Current Aerial Aerial imagery courtesy of Nearmap – May 2026 May 21, 2026 Council Action ▪ Development Agreement – 45-year contract (Item 38) ▪ Interlocal Agreement with Travis County granting City of Austin regulatory authority over the Dog’s Head (Item 39) ▪ Annexation Ordinance (Item 60) 7 July 23, 2026 Council Action ▪ Tax Increment Reinvestment Zone agreement with Travis County (Item 14) ▪ Tax Increment Reinvestment Zone preliminary project and financing plan (Item 15) ▪ Right-of-way vacation of portions of Hergotz Lane and Dalton Lane (Items 75 & 76) ▪ Annexation of 37 acres of right-of-way land (Item 106) ▪ Creation of TIRZ Zone, approval of boundaries, City participation rate, and appointment of the board of directors (Item 111) ▪ Development Agreement Amendment (Item 142) 8 Drainage & Environmental Regulatory Comparison Table (1 of 3) City of Austin Mining Reclamation May Development Agreement July Development Agreement Cut and Fill · Up to 4' allowed · 4'-8' administrative variance (with conditions) · 8+ Land Use Commission variance · Allowed to restore pits back to previous grade · Not applicable except in the CWQZ unless associated with necessary bank stabilization · No Change Critical Environmental Features (wetlands and springs/seeps) · Standard setback 150', may be administratively reduced to 50' · Wetlands protected per definition defined in 1987 US Army Corps of Engineers delination manual · Wetlands may be mitigation · Mining pits not exempt · Staff generally would allow mitigation for wetlands · Wetland protections do not apply if associated with previous mining activities · No Change Critical Water Quality Zone · Colorado River: 200'-400' buffer from Ordinary High Water mark (depending on location of 100- year-floodplain · Minor Creek: 100' offset from centerline · Intermediate Creek: 200 'offset from centerline · Major Creek: buffer from centerline · Depends on applicable code at time the mining operations began · Smaller drainages would not have been protected · Not applicable except for Colorado River · Colorado River buffer 200' · Development prohibited in Colorado River buffer except as provided in Development Agreement · Drainage channels will not be designated as CWQZs but those with at least 1280 acres must be restored as natural channels with native plants and natural materials · Some recreational activities allowed per agreement (trails, playgrounds, benches, etc) in large drainage channels · Minimum 200’ with a total acreage of 236.78 acres · A maximum of 118 acres of CWQZ to qualify as Open Space 9 Drainage & Environmental Regulatory Comparison Table (2 of 3) City of Austin Mining Reclamation Construction on Slopes · Limits construction on slopes for parking lots, driveways, buildings · Not applicable for mining pit reclamation Impervious Cover · 50% single family (5750 minimum lot size) · 55% single family (under 5750 s.f. lot size) · 60% multifamily · 80% commercial · Current code if new impervious cover proposed (unlikely with a mining reclamation) May Development Agreement · Not applicable to slopes associated with previous mining facilities July Development Agreement · No Change · No Impervious Cover limits outside of Open Space Areas · Open Space limited to 20% impervious cover · Maximum impervious cover for total gross site area is 79% · Maximum impervious cover designated as MDX is 85% (unless transfers approved) · Open Space limited to 20% Water Quality Treatment · Required for all new/redeveloped impervious cover greater than 8000 s.f. per ECM. Code allows alternative methods with conditions. · Current code if new impervious cover proposed (unlikely with a mining reclamation) Floodplain · City of Austin 100 year fully developed floodplain · Finished floor elevations required to be two feet above highest regulatory floodplain · Depends on applicable code at time the mining operations began but no adverse flooding impact would be allowed · Existing mining ponds may be used as water quality treatment if ECM requirements are demonstrated · Certain activities prohibited from draining to the ponds · Technical information to be provided in the Regulating Plan · FEMA floodplain controls · Allows flexibility to alter topography without having to update floodplain maps until regional drainage system is complete · Finished floor elevations required to be three feet above highest regulatory floodplain · No Change · No Change 10 Drainage & Environmental Regulatory Comparison Table (3 of 3) City of Austin Mining Reclamation May Development Agreement July Development Agreement Floodplain Modification Variance Approval · Requires restoration and/or mitigation payment into riparian zone mitigation fund · Environmental variances subject to LDC 25-8-41 and LDC 25-8-42 (Administrative or Land Use Commision) · No appeal available for a LUC variance · Floodplain variances require City Council approval · Depends on applicable code at time the mining operations began but no adverse flooding impact would be allowed · Floodplain modification criteria related to restoration/mitigation not required. · No Change · Depends on applicable code at time the mining operations began but no adverse flooding impact would be allowed · All LDC code requirements save for 25-2 Zoning are administrative, per Director of DSD · Denials are appealable to City Manager or City Council · No Change Erosion Hazard Zone · Applicable to all drainages of 64 acres or greater and within 200' of Colorado River Ordinary High Water Mark · Depends on applicable code at time the mining operations began but no adverse flooding impact would be allowed · Clarifies stormdrain outfalls are allowed in EHZ if protected works are provided (already a requirement in current code) Drainage · No Adverse Impact · No Adverse Impact · Regional stormwater system proposed (Local site-to-site No Adverse Impact still required) · No Change · No Change Tree Protections · Surveys required 19" or greater for single family residential, 8" or greater all others · Tree mitigation required for trees 8" greater that are removed (not including invasive species) · Protected trees - native trees 19" or greater · Heritage trees - some native trees 24" or greater · Depends on applicable code at time the mining operations began but no adverse flooding impact would be allowed · Tree protections apply but surveys are not required unless within the CWQZ · No Change 11 Effective FEMA Floodplain Maps • Development Agreement requires use of FEMA floodplain maps instead of City of Austin, fully developed floodplain maps • Image shows current Colorado River and Carson Creek floodplains FEMA Floodplains per Property Profile (dark blue 100-yr, light blue 500-yr, bright blue 100-yr shallow flooding) 12 Proposed Letter of Map Revision (LOMR) • Applicant proposing to remove mining pits from FEMA 100-year-floodplain maps (area in grey) • No changes proposed to FEMA 500-yr floodplain (orange) • Proposed change reviewed and approved by COA Floodplain Office • Pending FEMA review and approval 13 Next Steps ▪ Austin Strategic Mobility Plan amendment and Regulating Plan adoption ▪ Environmental Commission ▪ Planning Commission ▪ Urban Transportation Commission (ASMP only) ▪ City Council What is a Regulating Plan? ▪ Establishes land use and zoning for the property ▪ Development standards necessary to clarify regulatory framework established in the Development Agreement ▪ Once adopted, the Regulating Plan will be part of the City’s Land Development Code 14 Questions? 15