Shoal Creek: Downtown flooding revives Shoal Creek tunnel plan,
Austin city officials, suspecting there is only one way to keep the western end of downtown from being flooded every few years, have revived a big-money proposition: the Shoal Creek Tunnel.
The idea would be to channel floodwaters under the Lamar Boulevard area, as opposed to flowing over and through the commercial district. The project would be similar to the Waller Creek Tunnel, the controversial $150 million project on the other end of downtown that is now in the final stages of construction.
City officials say that internal talks are in the earliest stages. They are now troubleshooting assumptions about the flood-reduction options, which could lead to requesting money next year for the formal engineering that lays out options and underpins a decision, said Pam Kearfott, a supervising engineer in the city’s Watershed Protection Department. A final call is likely years away.
Still, a 1991 study by the city and the Army Corps of Engineers concluded that the
tight clustering of structures around that section of Lamar precludes other flood-control options — and since then, development has grown more dense in the flood-prone area between 12th Street and Lady Bird Lake.
“There is just not enough land available for detention ponds” or similar options, said Kevin Shunk, the city’s flood plain manager.
Engineering is not the only question. A Shoal Creek tunnel would probably be even larger than the Waller Creek Tunnel. Its hefty price tag would come with an implicit question: How much are Austinites willing to pay to prevent flooding in an area that is naturally prone to it? That section of Lamar Boulevard floods every few years, with business such as Shoal Creek Saloon sometimes taking significant damage. But flood insurance — and federal taxpayers, through their subsidization of the insurance — has usually covered much of the damage.
The Waller Creek Tunnel is being built partly to assuage fears that flooding presents a significant public risk. But Waller was also pitched as an economic development project that would spur development in what until recently was a moribund section of downtown.
Along Shoal Creek, a wave of new development is happening despite the flood risk.
“To what end would we build that tunnel?” said Ted Siff, president of the board of the Shoal Creek Conservancy, a group founded to deal with problems that range from bank erosion to graffiti. The conservancy is working with the city on a long-term plan for the watershed.
“That 1991 study, as I read it, does not say, ‘This many properties will be taken out of the flood plain,’” Siff said. “What we need is to be pursuing research into all the choices that may exist for flood mitigation.”
That 1991 study was an outgrowth of the efforts that followed the Memorial Day flood of 1981, which swept down Shoal Creek, along with Waller Creek and other waterways. It claimed 13 lives and caused an estimated $35.5 million in damage.
Following that flood, Austin enacted rules that limit the amount of “impervious cover,” or pavement, houses and other features that keep water from soaking into the ground.
Austin has also spent about $65 million on flood-control efforts in the Shoal Creek Watershed, including storm drain improvements in neighborhoods along the creek, buyouts of a few homes and upstream ponds to hold stormwater.
Likewise, downtown buildings are generally safer, with the Austin City Lofts and the Monarch examples of those near Shoal Creek constructed to more flood-resistant standards.
“The people who live there are still at risk, because they’re surrounded by water, but those buildings are at much less risk,” Shunk said.
The improvements the city can make will not fundamentally change the reality of the area’s flood risk, said Mapi Vigil, a managing engineer in the city’s Watershed Protection Department. Development patterns that predated modern standards have shaped the area. City codes now only require that new buildings not cause more flooding — and do not require them to reduce the flood risks.
The most obvious an- swer comes with a hefty price tag — as well as the political baggage of its counterpart across downtown, which was declared dead several times and then resurrected over 30 years, as the price tag rose from $25 million to $150 million.
Along the way, critics have accused the city of funneling public dollars to a project that would disproportionately benefit the people who own property along the creek. A special taxing district raises money to pay off the project, with 40 cents a month added in 2011 to the typical homeowners’ monthly drainage fee to pay for the tunnel.
In January, months after city officials discovered a tunnel design flaw, they pushed the finishing date back to June.