Staff recommend expanding erosion-hazard review to 200 feet along Colorado River below Longhorn Dam

City staff on the Watershed Protection Department briefed the Climate, Water, Environment and Parks Committee on a proposed amendment to Austin city code that would expand the erosion-hazard review area along the Colorado River downstream of Longhorn Dam from 100 to 200 feet.

Assistant City Manager Susana Carvajal and Watershed Protection Director Jorge Morales told the committee the change would amend Title 25 of the city code and respond to a council resolution that directed Land Development Code amendments tied to environmental, drainage and landscape requirements. Morales said the change is focused on erosion hazard zones — a technical review intended to protect buildings and infrastructure from riverbank erosion — and not a “no build” prohibition.

“We keep emphasizing this to our stakeholders. It’s not a no build zone,” Morales said. “It’s just, you need to look at erosion issues and protect whatever you’re building.” He and Watershed staff said the proposal would apply to new buildings and additions with habitable space and to city-regulated site plans, subdivisions and building permits inside the city limits; single-family residential lots within the affected corridor would remain under the existing 100-foot review zone under the version staff plans to bring to council.

Staff described outreach that included mailings to roughly 380 land parcels, an October public meeting at Montopolis Recreation Center and repeated stakeholder conversations. Public commenter Dale Glover, who identified himself as a property owner at 94 Montopolis Drive, told the committee some riverfront owners feel outreach in prior years was insufficient and said they would like more opportunity to provide input before council acts.

Committee members asked questions about where the ordinance would apply, how it would interact with existing floodplain and critical water-quality protections, and the potential financial and legal implications for landowners. Watershed staff said the erosion-hazard zone is a technical, site-specific permit review intended to prompt protective measures such as deeper foundations or engineered bank protection where warranted; they said it does not automatically prohibit development but that costs for redeveloping within the expanded zone could rise.

Key points staff presented: - Proposed change: increase erosion-hazard review distance from 100 feet to 200 feet downstream of Longhorn Dam for evaluation of new development with habitable space and infrastructure. - Scope: Applies to city limits site plans, subdivisions, building permits and any ETJ site plans subject to city site-plan rules; staff do not propose extending the 200-foot review to single-family lots or to subdivision and building permits in the ETJ where the city lacks subdivision authority. - Exemptions: Nonhabitable structures (sheds, small decks), areas beyond a parallel road and hard-surface trails within 100 feet would generally be excluded from the expanded requirement. - Outreach: Staff mailed affected property owners and occupants, held an October public meeting in Montopolis, and met with Travis County and the Lower Colorado River Authority. - Schedule: Staff said the ordinance is scheduled to appear on a March council agenda for action; the Planning Commission forwarded an amended version that includes a single-family carve-out for consideration.

Council members pressed staff on potential costs and liability, with staff noting they would follow up with the city law department about legal risks and compensation claims. Watershed staff also said their engineers evaluated wider buffer options but chose 200 feet as a balance between additional protection and limiting impacts; they estimated affected parcels in the hundreds for the broader river-critical-zone mapping but far fewer would be affected by the 100-to-200-foot change in ways that would trigger major redevelopment costs.

Staff stressed the policy intention is prevention: erosion has damaged homes, roads and pipes along the river, required expensive public repairs and continues to threaten public safety. The department said the change would help stabilize riparian corridors and reduce future taxpayer costs for emergency repairs.

The committee did not take a policy vote on the ordinance at this meeting; staff said they would bring the ordinance language and associated drainage/environmental criteria changes back to council for action on the scheduled date.