This article by Jack Murphy is the second of a two-part series on flood management. Read the previous article here. Follow our publications and events about living in the floodplain at #H2Ouston and #SyntheticNature.
These days, Shoal Creek starts artificially: Its headwaters, a mix of runoff and piped spring water, gather in manmade holding ponds above US Highway 183 before arriving into a ditch south of the frontage road. The creek flows, undetected, behind shops on Anderson Lane, through backyards and parks in Allandale, and next to Seton Medical Center before running alongside Lamar Boulevard. Downtown, its shores are lined with condominiums and the construction sites for future condominiums. Its waters pass Austin's new central public library designed by Lake Flato and Shepley Bulfinch — almost open — prior to joining the Colorado River.
Shoal Creek, 14.3 miles in length including tributaries, constitutes a core sectional cut of central Austin. Like at Waller Creek, citizens are working to spur progress that will improve flood control, public trails, public parks, and historic awareness. But Shoal Creek advocates hope to use very different tools to accomplish their goals.
Shoal, like other Austin creeks, has been a source of water issues since the city's founding in 1839. Unlike Houston's low-lying environs, Austin's water problems stem from flash floods through creeks that could go dry for months afterwards. Various floods have claimed lives and property over the decades with frustrating regularity. The 1981 Memorial Day Flood killed thirteen people and ruined businesses along Lamar Boulevard. Since then, according to the Austin American-Statesman, $200 million has been spent to buy and raze 450 flood-prone homes along creeks, build flood walls and retention ponds, expand creeks like Shoal Creek for more water-carrying capacity and improve storm drains in older neighborhoods.” Additional floods took place in 2001 and 2013 prior to the more intense 2015 Memorial Day flood, which put the same part of town underwater again (damage was worse in the Hill Country and in Houston). In this incident, the creek grew exponentially from its normal flow rate of 90 gallons per minute to 6,000,000 gallons per minute. [i] Some parts of the trail along the creek were washed out and are still not reopened, almost two years later. The potential for increased flood intensity due to development in the watershed has, in recent times, been barely matched by the improvement of safety notifications, rescue operations, and stopgap maintenance. Current city materials list lower Shoal Creek, from 15th Street to Lady Bird Lake, as the worst flooding problem in Austin.
To eliminate flooding along Waller Creek, on the east side of downtown, the city commissioned a 20- to 26-foot diameter tunnel to divert flood waters, turning its lower reach into a controlled flow environment. A similar tunnel solution for Shoal Creek was studied in a 1991 Army Corps of Engineers report; while it did not move forward, other recommended improvements from the report were realized. In 2014, the Watershed Protection Department revisited the study and initially explored a 26-foot diameter tunnel that would run 6,000 feet from 19th Street to the lake at an estimated cost of $133 million. Its proposed inlet was to be within Pease Park, a cherished open space gifted to Austin in 1875 by former Texas Governor E.M. Pease. Given the power held by adjacent neighborhood groups in this wealthy area and the intense NIMBY sentiments that suffuse local politics and policies, it is unlikely that such an intensive solution will be viable without a major battle. Such a facility would be fought tooth and nail as evidenced by a strongly-worded 2016 press release from the Pease Park Conservancy that urges City Council to "only consider solutions that do no[t] [sic] alienate any dedicated parkland" and to not waste taxpayer dollars on "studying a flood control system that will be dead on arrival and never built." The land, the release states, was given to the City and was stipulated to be a park, so therefore "taking portions of the park for other divergent uses could violate the terms of that deed and be certain to subject the City to costly litigation." It's clear that what worked for Waller Creek in Austin's central business district won't work for Shoal Creek's residential environs. How, then, to mitigate flood risk?
“Really the only way to reduce flood risk in lower Shoal Creek is to retain it somewhere upstream,” says Ted Siff, president of the Shoal Creek Conservancy (SCC), a non-profit founded in 2013 to study and support improvements to the creek. Currently the City of Austin is undertaking a study to investigate “a variety of options that might help with flooding.” Siff says the study “wouldn't be anywhere near as robust as if the SCC wasn't involved.” Through the SCC's efforts, the budget of the study was increased from $500,000 to $900,000, and rather than being a “tunnel alternatives” plan, the study will take into account a wide range of solutions — of which a tunnel is just one, though an unpopular one. SCC CEO Joanna Wolaver remarked, “if we're talking about flooding in the downtown area, educating people about green infrastructure [upstream] can have a positive impact on reducing flooding.” This shift in presentational tone showcases the SCC's interest in advancing distributed landscape solutions.
The SCC's progressive approach is an essential part of its mission. The group emerged from a series of stakeholder meetings where its leaders realized its problems — “devastating flood events, poor water quality, erosion, loss of native habitat, and loss of productive spring flow” — could only be solved at the scale of the watershed. While the Waller Creek Conservancy expertly focuses on a single 1.5-mile stretch of its creekbed, the SCC addresses the 13.1 square miles of city that drain to Shoal Creek. It advocates for the watershed as a logical governmental unit of the city, where environmental issues can be improved through the efforts of those who are directly affected by the outcomes. This suggestion redefines a neighborhood from an urban entity to a topographic one, where our relationship to water delineates organizational borders [ii]. On Shoal Creek, the dreamed alterations are not bound to one silver bullet improvement, but instead imagine a host of networked retention concepts that would integrate with the surrounding urbanity and suburbanity. There are two camps on how to address floodwaters; there are solutions that, in Siff's understanding, treat “water as something you get rid of, and solutions where it is treated as a resource that's valuable to manage.” Shoal Creek's future, it seems, may well be found in the second group.
To aid the city in brainstorming solutions, the SCC has released its own report to promote worthwhile case studies. The report gathers ten case studies in "innovative stormwater management and flood mitigation." Each example demonstrates how infrastructure can be a public amenity, not a liability.
One concept is to design recreational open space to be floodable — for parking lots, recreational sports fields, parks, utility zones to be designed and contoured to accept periodic inundation. Projects like the Waterplein Benthemplein in Rotterdam and the Rabalder Skatepark in Roskilde, Denmark are built examples of this strategy. Poreform Urban Skin in Las Vegas, the Mirabeau Water Garden in New Orleans, and the Sankt Kjelds Climate District in Copenhagen are proposals yet to be built but would, as conceived, behave similarly. These designs offer surface or subterranean solutions that would be called upon a couple times a year to store and release floodwaters safely. Though not featured, Houston's Buffalo Bayou Park, Bayou Greenways, and Willow Waterhole fit this model.
Other case studies, like the Supertree Grove in Singapore or BIG's Dryline project in New York City investigate how stormwater or storm surge fortifications can be turned into park assets and placemaking improvements. Still others showcase how resiliency could be achieved architecturally. Tokyo's massive G Cans, a $2.9 billion cistern is perhaps the most construction intensive example, built in 1991 after typhoon flooding killed fifty-two people. Like Houston's Buffalo Bayou Park Cistern on a massive scale, the columned concrete megastructure hold about 9,500 acre-feet of water, meaning a football field-sized column of water that stands 7,200 feet tall.
Many of these solutions make sense when given tabula rasa to build from scratch but would be difficult in Austin without a serious land acquisition program. The remaining open areas in the watershed are disappearing; in December last year, final approval was issued for The Grove at Shoal Creek, a development that create a mixed-use district on a 75-acre, Nevada-shaped parcel along the creek. While its “signature park” separates the creek from any structures and green streets initiatives will be used, no larger retention strategies appear to be in place.
One path forward from these case studies is a worthwhile thought experiment: Imagine, for a moment, cisterns of some tolerable scale and form distributed throughout the upper watershed, forming a constellation of holding tanks that would fill in overflow conditions. This new kind of water infrastructure could be made visible throughout the mostly residential neighborhoods. Austin previously built moontowers to distribute light; in the future there could be floodtowers to accumulate stormwater. Wolaver, in conversation, also mentioned the possibility of storing water underground in aquifers, to either be slowly released into the creek or used locally, or to even recharge the Edwards Aquifer. Groundwater recharge via stormwater management is an enticing idea that is being researched elsewhere, notably in California. The idea immediately presents issues of filtration and treatment to ensure aquifers remain unpolluted. But what if flood mitigation and groundwater depletion could be symbiotically addressed with one intervention?
Siff also draws inspiration from Houston's Harris County Flood Control District and its efforts to purchase land for retention, constituting a kind of flood land banking. (Milwaukee also has a similar program in place, called GreenSeams.) With Shoal Creek watershed's already at 53 percent impervious coverage and with more development still to come, action is needed to prevent future floods.
There are big ideas at play here, and they will hopefully be considered by the City and their consulting engineers during their study as potential solutions. But they will be measured against the facts and figures of the creek's intensive flooding. It is important to understand that these ideas are all presented in tacit opposition of any kind of tunnelized solution, due to its potential alteration of Austin's “central park.” John Middleton, a civil engineer with Austin's Watershed Protection Department, cautions that it is first and foremost an issue of volume and flow rate when studying these major incidents. [iii] Middleton admits a tunnel is an “attractive way to whisk water out of an area,” but is well aware of the extreme sensitivity attached to this endeavor. (A tunnel beginning at 19th Street would also do nothing to help residents and structures further upstream.) He notes that some of the SCC's case studies deal with “different hydrologies” that vary widely from local conditions of the case study projects. Creeks here may experience catastrophic flows regardless of how impervious their watersheds may be. Hill Country creeks experience wide dry/wet variability, sometimes going months without flows before a deluge drops something like ten inches of rain over twelve hours, resulting in flooding regardless of impervious cover considerations that accompany development. The most deadly flood in Shoal Creek's history happened in 1915 and killed twenty-three people, with little development at that time realized outside of Austin's central core.
As the study moves forward, terminology will be a tightrope. The effort's official title is the Shoal Creek Flood Mitigation Study; the project narrative states that in the past the city and the Army Corps of Engineers “looked at the possibility of a tunnel to help divert floodwaters. This will be one of many options considered in the study.” The introduction also states that the study will “take into consideration the recreational, historical, ecological and culturally significant aspects of potential sites for flood mitigation strategies.”
The core ideas in the SCC's case studies are, largely, not new technologies. Over the past two thousand years cisterns were used to drain cities around the planet — Rome, Turkey, and London come to mind as examples. Even surface retention was a necessary tool for capturing seasonal flows for crops, as with flooding along the Nile. Floodable urbanism is not even new in Austin's aquatic discourse. In Life on Waller Creek, published in 1982, University of Texas English Professor Joseph Jones reflects on the history of Austin and his personal connection to the waterway that runs through campus. In a final chapter titled “Drainage Ditch or Garden Park?,” Jones quotes an unnamed “forward-thinking engineer” about flood mitigation solutions:
Flooding problems and unsightly channel improvements on Travis County creeks will continue so long as natural flood plains must support land uses which are incompatible to the land's flood drainage functions. Parks, greenbelts, ball fields, and other recreational facilities are excellent examples of land uses which are not vulnerable to costly flood damage, and which at the same time can utilize and preserve much of the natural attractiveness of Austin area creeks and adjacent land. Greenbelt and recreational use of flood plains and drainageways can also reduce the need for costly storm sewers, and expensive creek channel improvements.
Some surface stormwater retention, Middleton notes, is already in use in this watershed. Great Northern Dam, east of the MoPac expressway, performs this task; its trapezoidal retaining slopes are open for recreational use until the pond fills up. Northwest District Park has been renovated for its tennis courts and parking lot to serve as creek overflow. When the waters rise, they rush over a concrete side channel weir and drain back at a slower rate after the flood risk abates.
Retention, in the future, could also take place at the scale of the residential lot, where widespread adoption of pervious policies can sum to make a notable impact. Philadelphia, as an example, is five years into a green infrastructure program that encourages residents and businesses to take these steps, and maintains a GIS map of projects. Austin already has “green streets” initiatives, with bio-swales, vegetated bump-outs, rain gardens, and porous pavers entering the lexicon of the urban streetscape. If there is to be any real reduction in flooding during cloudbursts, this vocabulary needs to be robustly deployed to gather water in manageable amounts throughout the existing city. [iv]
Beyond the intense issue of flood mitigation, the SCC is at work visioning other improvements for the creek, including updated trails with a modern width of 12 feet for comfortable walking and biking in both directions. Shoal Creek's trails, built in the 1960s as the first trails in the city, wind from the lake to 38th Street but are in poor shape due to decades of use without major repairs.
Future SCC master planning efforts will also study how to extend the trail north as to link into a growing network of urban trails in Austin. Parts of the existing trail were destroyed in the 2015 flood, and since then bank stabilization has been underway almost continuously (The construction also abandoned and removed sections of sewer lines: because creeks form in lowest areas for reasons of gravity, most sewer lines were placed there for the same reason and were never removed). The creek moves through many parks, each with its own room for updates. Pease has its own support group, the Pease Park Conservancy, that fundraises and visions for their own improvements. Some, like Custer's Meadow, an area designed to slow stormwater, deal with water management, but most initiatives are for trail improvement, facilities expansion, and signage and wayfinding. Currently, the city is designing a new 12-foot-wide trail from 15th Street to 5th Street that will improve access and, finally, install lighting.
Downtown south of 5th Street is the most physically transformed portion of Shoal Creek and, also, the oldest part of Austin. In 1838, a few settlers lived along the creek's mouth in the village of Waterloo when Mirabeau Lamar arrived scouting locations for Texas's new capitol. Nearby, Lamar famously shot a large buffalo and, taken with the area's scenic beauty, returned to Houston to recommend the place to become the young nation's capital. [v] After the town was laid out, this southwestern quadrant was used for a variety of utilitarian purposes. It was, according to early maps, a penitentiary, a water plant, and a cotton compress facility. Later the city's Seaholm Power Plant and Greenwater Water Treatment Plant each occupied a side of the waterway. Now, after decades of work, these parcels have been either repurposed or sold off by the city, and the area has been reborn as a district of new towers. First wave cultural improvements like Ballet Austin's facility feel out of scale and don't capitalize on the allowable floor-to-area ratio (FAR) onsite; the nearby Austin Music Hall, built in 1995, has already been demolished to make way for a 28-story office building. Full city blocks developed by Trammell Crow are finishing soon (Google is one anchor tenant), the slabs for the “tallest residential tower west of the Mississippi” are rising higher, and the new central public library is slowly nearing completion, all accompanied by public space improvements along the creek. This new live/work nexus feels ambitious and slickly urbane, but it is the density that new Austin needs, even if it is luxury housing. [vi] The trend, viewed from a more historic perspective, can also be seen as a welcome return to the banks of Shoal Creek, with new residents living in the place where Waterloo's first citizens made their home almost two hundred years ago.
Lined with condominiums and crossed with bridges, Shoal Creek south of 5th Street feels, lately, like an urban canyon and it is here, due to the volume of water in motion, that the flood risk is most dangerous. Concrete retaining walls are being constructed on its western bank and a new path will carry trail users south to the library's eastern terrace and under Cesar Chavez to the Hike and Bike Trail, where the creek's peninsula, built in the 1960s to ensure the power and water plants didn't draw in polluted Shoal Creek floodwaters, was recently renovated to prevent further erosion.
In this lower section of the creek, the task is not retaining water but making sure it leaves quickly. Any design improvements must be thoroughly engineered to be sure they don't pose a flood risk by trapping debris and making the conditions worse. In a situation where flood modeling decides what gets built and each landowner must make a choice about how to improve its creek frontage without a prescribed design framework, the SCC becomes an advocate for the commons, working with all parties to make sure quality public access is maintained. Wolaver said that Cirrus Logic, a semiconductor company, operates two buildings downtown, and hopes an improved creek can serve as a walkable connector between their campuses. [vii] An improved trail will not just be a benefit for runners and bikers, but in the future, the thinking goes, would serve as an improved transit pathway through a thoroughly urban downtown.
Whereas Waller Creek utilizes a more robustly engineered solution to deal with flooding that qualifies as big project infrastructure, the vision for Shoal Creek attempts to maintain its natural, bucolic image. Its upcoming synthetic improvements will hopefully be distributed, networked, and localized — built into the many neighborhoods it serves. This dichotomy of character — Waller as urban, Shoal as natural, both “bookends to the city” — is as old as Austin itself. Even in its initial layout, Shoal's path wandered west of the original polis, while Waller was threaded through and below the proposed streets. What would Austin look like it if its original surveyors had adjusted the city to its creeks, instead of running its Cartesian grid over the existing terrain? Even in a birds' eye view of Austin drawn by August Koch in 1887, Waller cuts through streets, with erosion of East Avenue present in the rendering of the image, while Shoal, though industrial with its early water plant and cotton facility, is, upstream, left to its natural ravines. These early aspects of civic development still factor significantly into public conceptions of Austin's waterways and into what types of improvements are deemed appropriate for each locale.
Shoal Creek was named for its shallow deposits of sediment, easily forded, at its junction with the Colorado River. Now, with literal shoals of people walking, running, biking, and commuting along its edges, the waterway lives up to both definitions of its name. Shoal's stormwater study is just getting underway, as its first public meeting for citizen feedback took place March 9 with engineers from Halff Associates presenting the initial conditions of their work, and with the information boards arranged around a Cirrus Logic assembly room for a crowd of citizens to peaceably review. The study's results stand to have long-lasting impacts on the health, safety, and beauty of this watershed, and will hopefully kickstart some kind of innovative stormwater solution. Shoal Creek's synthetic future is inevitable, as the intensive development that lines the creek downtown is existentially dependent on reliable flood mitigation to safeguard its residents and structures. The task ahead is to decide — and design! — what it will look like. If Austin is as good at changing as our Mayor believes, now is our chance.
Ted Siff, SCC president, has lived blocks from Shoal Creek for forty years because it allows him to “be close to nature while being in the middle of downtown.” When asked about the goals of the organization, he reflects, “In a perfect world — or even a better world, 5 or 10 years from now — I would love [for] people who live or work in the watershed to know they live or work in the watershed, because they have more knowledge about what's happened here in the past and what's happening here now, and what there is to enjoy about it.”
[i] In fact, the damage was depressingly similar between the 1981 and 2015 floods. Cars were washed away and the same structures were flooded, but instead of the original Whole Foods location being inundated, viewers watched as the kitchen at the historic Shoal Creek Saloon was flooded.
[ii] If applied nationally, it would have a dramatic effect on the shape of our nation; another map exercise is here.
[iii] The WPD owes its existence to Shoal Creek: After the floods in 1981, the department was carved out of the Public Works Department to focus on stormwater issues.
[iv] Wolaver also mentioned a “sponge city” in China, where open space is explicitly designed to work as a wetland: The Qunli Stormwater Wetland Park in Harbin, a city in northern China. Designed by Turenscape, the park preserves the existing wetlands by building only on the perimeter of the expanse, allowing stormwater that drains to this low spot to be filtered before seeping into the ground, and providing a linear park of trails, platforms, and overlooks for users. Turenscape, partnered with Lake|Flato, was one of the finalists for the Design Waller Creek competition in 2012.
[v] This, it seems, is the first instance of the timeless Austin joke that the city was always better five years before you arrived — regardless of when you arrived — and that it was those who arrived after you who truly ruined its appeal. One can fictitiously imagine a similar groan from Jacob Harrell and the families that lived in Waterloo when Lamar arrived in 1838, had a blast, and decided this was the place to be — not unlike decades of SXSW attendees who spend a week here and return home to still-wintry climes to wax nostalgically about Austin as the promised land of endless summer.
[vi] While these are expensive residences, there will be be 80 units available at 80 percent median family income for the next forty years. And, much more importantly, the city has committed 100 percent of the property taxes from formerly city-owned properties to the Housing Trust Fund, which funds affordable housing within the city limits. This value was previously 40 percent of tax revenue with a cumulative total of $27.3 million, but this updated sum is expected to generate $68.2 million.
[vii] Cirrus Logic is an ongoing supporter of the SCC, and currently provides office space for the non-profit.