Updates to erosion protections coming to Council

During the inaugural meeting of City Council’s newly formed Climate, Water, Environment, and Parks Committee on Feb. 26, members heard a briefing on a proposed ordinance from the Watershed Protection Department (WPD) to increase erosion protections along the Colorado River.

The Austin-area segment of the river crosses several jurisdictional boundaries, including the Travis County line, Austin’s extraterritorial jurisdiction (ETJ), and Austin’s full-purpose (city) boundary. The proposed changes would widen the erosion hazard zone downstream of the Longhorn Dam and update EHZ regulations throughout the city. Later, via a separate process, WPD hopes to improve drainage design requirements to mitigate extreme erosion. WPD has created an interactive map where Austinites can view the current and proposed protections.

The areas in question have particularly sandy soil, which is more susceptible to erosion. The process of erosion removes topsoil, reducing an area’s capacity to absorb water. In turn, heavy rains are more likely to yield rapid surface runoff, leading to flooding.

During the briefing, WPD Director Jorge Morales pointed to the 2015 Halloween floods as an example. “We’ve already seen erosion threaten or damage homes, small businesses, roads, pipes and other infrastructure in this area, and millions of dollars in public money has been spent to fix problems caused by the erosion,” Morales said.

WPD’s updated protections would widen the erosion hazard zone from 100 to 200 feet. Essentially, this change would require impacted homeowners (past the Longhorn Dam) seeking to expand their house or build a guest house to implement more protective measures.

The proposal also aims to clarify and to adjust the scope and impact of erosion hazard zone regulations throughout the city, not just along the river. This widened zone would apply to new buildings with habitable space and infrastructure, all development within city limits (including subdivisions, site plans, and building permits), and site plan development in the ETJ.

Exceptions remaining within the existing 100-foot requirement would include non-habitable structures, areas with a parallel road running between them and the river, residential subdivisions and building permits in the ETJ, and hard surface trails.

The ordinance is in response to a 2022 Council resolution which initiated amendments to the Land Development Code related to environmental, drainage and landscape requirements. Over the last few months, the proposal has been discussed with the Codes and Ordinances Joint Committee and the Environmental Commission. WPD has also conducted several open houses for community feedback.

The Planning Commission vetted the proposal earlier this week and recommended several changes, which WPD said they intend to incorporate. One of these would exempt single-family lots in response to stakeholder feedback, allowing them to remain within the 100-foot requirement.

During the briefing, staff also addressed the existing regulatory limits for development in the area that would be impacted by the widened EHZ. “There’s already a 100-year floodplain, there’s already critical water quality zone (CWQZ) buffers, and there’s already a (100-foot) erosion hazard zone review buffer. And as we go through it, we’re focusing on additional regulations for a waterfront overlay on the Red Bluff and wildland-urban interface that … you’ve heard about as well,” Morales said.

Matt Hollon, WPD project lead, noted that the critical water quality zone is a riparian zone buffer, and necessitates low intensity or non-infrastructural development requirements. Meanwhile, the erosion hazard zone, implemented by the city in 2013, aims to prevent erosion.

“(The two zones) complement each other, but they don’t have the same geometry or main objectives,” Hollon said. “The erosion hazard zone is not a no-build zone … it doesn’t prohibit anything,” he added. “But … costs are going to go up if you do want to build something there.”

Council Member Mike Siegel highlighted concerns raised by several property owners from in between the Longhorn Dam and the Montopolis Bridge, who feel their area should be exempted because that part of the river is already subject to more protections.

“We do believe that the 100-foot boundary is just not protective enough. …Our engineers even looked at even wider buffers, but we decided to leave it at 200 because it coincides with the critical water quality zone (which WPD has currently opted not to change),” Hollon said in response. “Most development is already going to have to stay out of the 200-foot zone … there’s basically no impact unless (property owners) have the right … on a site plan or a subdivision, to redevelop their existing impervious cover.”

“Y’all could certainly introduce an amendment that exempts folks between Longhorn (Dam) and 183,” Hollon added. “Honestly the main people affected would maybe be Parks and Recreation (with Roy G. Guerrero Park).”

He emphasized that the impacted properties in the widening EHZ numbered in the range of 200, with many located in the ETJ (and thus only impacted in the instance of a site plan).

“Not to undermine the ordinance, but … we’ve kind of right-sized this at 200. … Most properties … have no change,” he said. “We wanted to send a message about risk, and we wanted to also make sure our own city infrastructure – our parks, our roads, anything new – also abides by the 200 feet.”

“This is definitely a signal to folks who live along the river that this … is a concerning situation,” Hollon said. “People need to recognize the risks and prepare for it.”

Committee Chair Ryan Alter seemed to back the proposed changes. “No one likes being told they can’t do something, but I feel like they’d like their house falling into the river even less,” he said.

Bobby Levinski, a senior staff attorney with Save Our Springs Alliance, told the Austin Monitor that SOS generally supports the enhanced protections, but has concerns about the possible exemption for hard surface trails. “Adding pavement along the free-flowing section of the Colorado River could cause the very erosion that this ordinance is intended to address,” he said. “We’ve asked some questions related to that proposed exemption and hope to get a response soon.”

Council will consider the ordinance on March 6. Morales said during the briefing that WPD will continue to solicit feedback on the criteria changes later this spring.

Photo made available through a Creative Commons license.

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