22 minute read
Outstanding Environmental & Engineering Geologic Project Technical Program Schedule
AEG Outstanding Environmental & Engineering Geologic Project Award Mission Reach of the San Antonio River Walk
Project Team: The San Antonio River Authority Bexar County, City of San Antonio, USACE, Jacobs, and Zachry Construction Corporation
The Mission Reach of the San Antonio Riverwalk restored native habitats and added recreational amenities while maintaining the flood carrying capacity of the channel.
National and International Significance of the Project
The San Antonio River Walk is world renowned for being lined with hotels, restaurants, and retail which plays host to large river parades that bring over 100,000 people to the river as well as small intimate gatherings like private weddings on Marriage Island. Prior to the pandemic, a recent economic impact study conservatively concluded that 11.5 million people visit the San Antonio River Walk annually, and those visitors stimulate an overall annual economic impact of $3.1 billion and support over 30,000 jobs.
The River Walk began in the 1930s, and in 1998, Bexar County, the City of San Antonio, and the San Antonio River Authority (River Authority) launched the San Antonio River Improvements Project (SARIP) to expand on the success of the original river park. The SARIP included the innovative Mission Reach Ecosystem Restoration and Recreation Project (Mission Reach). In June 2008, construction began on the $271.4 million Mission Reach portion of the SARIP. The Mission Reach project is one of the largest urban ecosystem restoration projects in the nation and the first of its kind to be justified through the U.S. Army Corps of Engineers (USACE) ecosystem restoration cost-benefit process. The project was completed in October 2013.
As the Mission Reach project restores the natural ecosystem of the river and provides new recreational benefits, it also reconnects the river to the historic Spanish Missions that relied on it hundreds of years ago. The San Antonio Missions were recognized in 2015 as a UNESCO World Heritage site,
the first such designation in Texas. The Mission Reach project was part of the nomination process and played an important role in the United Nations inscription process.
Additionally, by helping to demonstrate that flood mitigation and urban ecosystem restoration can be successfully integrated, the Mission Reach was a significant reason for the San Antonio River being recognized as the winner of the 2017 Theiss International Riverprize, presented by the International RiverFoundation. The Riverprize is the world’s foremost award in river basin management. It recognizes and rewards organizations making waves in the sustainable management of the world’s rivers, whether at the grassroots or transboundary level. The prize rewards inspiring initiatives that demonstrate Integrated River Basin Management to restore and protect rivers, wetlands, lakes, and estuaries.
Project Description
Some historical context must be provided to fully understand and appreciate the accomplishment of the Mission Reach project. Flooding has plagued the City of San Antonio for generations, including deadly flooding in 1913, 1914, 1921, and 1946. Following the devastating flood in 1946, the River Authority began working with the USACE to develop strategies that address flooding in and along the San Antonio River and its tributaries. In 1954, the U.S. Congress authorized the USACE to construct the San Antonio Channel Improvements Project (SACIP).
Through the SACIP, the River Authority worked with the USACE on major realignment and channelization to 31 miles of the San Antonio River and its tributaries. Two underground tunnels, one at the San Antonio River and the other at San Pedro Creek, also divert floodwaters from San Antonio’s central government and business districts. These improvements serve as the backbone for the community’s floodwater conveyance system and protected San Antonio from significant loss of life and property damage during other destructive storm events in 1998, 2002, 2013, and 2015.
The channelization authorized by the SACIP straightened and widened the river south of downtown turning the river into a trapezoidal channel more akin to a drainage ditch than a river. The grass-lined channel was devoid of native vegetation, contained no woody vegetation, and had little riparian or aquatic habitat value. While the channelization worked for flood mitigation, by 1998 citizens were seeking to restore the San Antonio River to a more natural and native habitat.
Therefore, the challenge of the Mission Reach project was to maintain, or improve, the flood carrying capacity of the river channel while implementing ecosystem restoration in an urban environment (See Figure 1.). Adding recreational elements to the project further complicated the project goals. The engineering design of the Mission Reach is intended to increase the quality, quantity, and diversity of native plants and animals along eight miles of the San Antonio River just south of the city’s urban downtown core (the City of San Antonio in the seventh largest city in the nation).
The Mission Reach project includes the restoration of approximately 334 acres of riparian woodland habitat. This includes the planting over 10,000 pounds of native grass and
Figure 1. The care and management of water in the river channel was a major challenge during the five-year construction of the Mission Reach ecosystem restoration project.
Figure 2. Important aquatic features, such as riffles, were restored to the San Antonio River, and within a few short years, the habitat of the river is showing strong signs of improvement.
wildflower seeds of over 60 different species and close to 23,000 native trees and shrubs, including 40 different species. The Mission Reach project was designed to mimic the diversity and density of a naturally occurring riparian area that exists during drought and flood conditions. Trees were planted approximately two years after the completion of each phase of the Mission Reach to give time for the vegetation and grasses to become established.
Previous flood management efforts had channelized the river and eliminated many of the features that allow for a diverse river ecosystem to thrive, but the Mission Reach helped to revitalize this incredible aquatic habitat. River restoration was accomplished by returning natural river features to 113 acres along the river and restoring two historic river remnants. Natural river elements, such as riffles, runs, pools, and embayments (oxbow lakes, wetlands, or natural backwater habitats) provide different types of habitat to maintain a native, diverse, and healthy aquatic ecosystem (See Figure 2.). • A riffle appears as shallow choppy water as it quickly bubbles over rocks. This action brings oxygen into the river for aquatic species and provides valuable habitat for insects and small fish. • A run is generally a larger area of average depth and velocity. Riffles and runs will lead to larger areas of deep, slow moving water called pools. • Pools provide an area for the sediment in a river to deposit and provide valuable habitat during times of low water where larger species of fish can reside. • Embayments form naturally as bends in the river become crescent-shaped bodies of still water. These areas provide habitat for plants and animals that do not thrive in the flowing water of the river, while also helping to process and filter floodwaters before they move into the river.
The Mission Reach looks much different than the historic San Antonio River Walk and the Museum Reach area of the river north of downtown. (The Museum Reach is the other aspect of the overall SARIP that was initiated in 1998 and is also an engineering success story.) The native landscape of the Mission Reach looks wild rather than manicured. Grasses and wildflowers are allowed to grow to their natural heights rather than mowed. Boat traffic on the Mission Reach is limited to canoes and kayaks rather than barges. While it will take approximately 50 years for the entire ecosystem restoration process to fully mature, the project is already growing in well. The existing riverine habitat already provides a serene, natural landscape where visitors can enjoy the inherent beauty of the river, and it will only get better in time!
Improvements along the Mission Reach focused on ecosystem restoration using an engineering technique known as fluvial geomorphology, which is the study of the processes and pressures operating on river systems. This technique transformed the straightened river by adding sinuosity where possible while maintaining flood control, reducing erosion, re-introducing native vegetation, and creating an environment more suitable for recreation and wildlife. Hydraulic and Hydrology models were used to design the project. The engineering models were not only used for traditional floodplain mapping, but also to help identify where the optimum location to plant each of the over 23,000 trees along the river to ensure the proper conveyance of flood water while restoring the ecosystem to a more natural and native habitat (See Figure 3.)
• There were several different engineering challenges faced when designing this project, including: • The USACE requirement to maintain or improve the current flood mitigation capacity of the river channel. • Reshaping the river to make it appear more natural by the excavation of 3.5 million cubic yards of earth.
Figure 3. Engineering models identified four different vegetation zones with specific densities and placement locations for trees and shrubs to ensure proper flood conveyance in the main channel.
• To maintaining slope stability as the river was reshaped, six different types of stabilization techniques were implemented to protect the project: - Temporary EC Blanket - Permanent EC Blanket - Stone Gabion Blanket - Riprap - Organic Compost Mulch - Cellular Confinement Mat • The implementation of grade control structures (e.g., wiers and riffles) during the process. • The restoration of meanders and two old river remnants. As the river was reshaped to better mimic the original flow, four different types of “Toe” techniques were used: - Vegetated Geogrid Toe - Coir Roll Toe - Rock Riprap Toe - Gabion Box Toe • The restoration of riffle, run, pool habitat within the actual river channel. The riffle, run, pool sequence is incredibly important for aquatic health and therefore is an important feature of this project. Over 30 riffle structures were added back to the river. • Creating embayments (i.e., wetland or natural backwater type habitat) throughout the project. • Improving aquatic and riparian habitat along eight miles of the river.
The engineering demands of this project were extraordinary as the goal of the project was to restore a native aquatic and riverine habitat all while maintaining (or improving where possible) the existing 1% annual chance (i.e., 100-year) floodplain. The project not only had to meet the rigorous specifications of the USACE, but also the high expectations of the local community who were deeply involved in this extremely visible, long-term public infrastructure project. Today, the average visitor to the project only sees a beautiful river and surrounding native habitat, and they are completely unaware of the intricate engineering that went into restoring the river and its habitat. (See Figure 4.)
Figure 4. Today, visitors only see a beautiful river and surrounding native habitat, and they are unaware of the engineering design and construction that restored river. Figure 5. Since the Mission Reach project was completed in 2013, over 300 different species of native herbaceous and woody vegetation have been documented along the river.
Protection and Enhancement of the Environment
The Mission Reach has two formal goals related to vegetation coverage and vegetation diversity which were agreed upon by the USACE and the River Authority. The Mission Reach will sustain coverage of native vegetation throughout at least 70% of the project area to maintain the stability of the San Antonio River, improve water quality through stream buffering, and create riparian habitat. Additionally, the project will maintain a diverse mix of native plants throughout at least 50% of the project to promote a diverse resilient riparian ecosystem. As of 2020, estimated native vegetation coverage is at 54.3% (70% is the target goal) and estimated diversity of native species distributed throughout the planted area is at 50%, which is hitting the target goal. (See Figure 5.)
The Mission Reach restoration is less than a decade old, but the habitat is already demonstrating that ecosystem restoration can work in an urban environment. The project has also provided the River Authority with numerous opportunities for proactive studies and additional ecological restoration. The first initiative undertaken to restore a native population was the reintroduction of Guadalupe Bass. This endemic species has now spread all the way from San Antonio where it was re-introduced down to Goliad State Park, which is nearly 200 river miles away!
The River Authority then conducted a three-year avian study which counted over 65,000 birds using the restored habitat, including over 205 different species. This included both residential bird species that live here all year round and migratory bird species that travel through the Americas using San Antonio as a rest stop. Some notable observations included an interior least tern, which is federally listed as endangered; Cassin’s kingbird, which is only the second record of this species in Bexar County; white-rumped sandpiper, which migrates 8,000 miles each way; and a bald eagle was recorded temporarily nesting in an area not too far from downtown. (See Figure 6.)
The next study was conducted to determine if the aquatic habitat would be suitable for freshwater mussel species. The Mission Reach aquatic habitat, which is within an urban environment, has been determined healthy enough to support mussels, and beginning late 2021, River Authority staff will start the reintroduction of four freshwater mussel species into
Figure 6. Native Black-bellied Whistling-Ducks using an embayment (backwater) habitat, photographed early in the morning during a Mission Reach avian study.
the Mission Reach. The San Antonio River will be the first waterbody in the state to have an assemblage of mussels reintroduced. These organisms are ecologically and culturally relevant and were a food source for indigenous peoples. By reintroducing this filter feeding “Liver of the River,” the ecological foundation of this stretch will be bolstered.
Finally, in 2015, the City of San Antonio was designated as the first Monarch Butterfly Champion City by the National Wildlife Foundation (NWF) for outstanding efforts to tend, foster, and honor these creatures. San Antonio is a crucial flyway for millions of Monarchs every spring and fall as they travel from Mexico, through the United States, and onto Canada (and back). The San Antonio community adopted all 24 NWF pledge suggestions—many of which were related to the Mission Reach—making San Antonio the first city in the nation to do so and moving the NWF to create this entirely new category for San Antonio to recognize this accomplishment.
Benefit to the Public
In addition to the incredible environmental benefits, that were constructed to maintain or improve flood conveyance, the Mission Reach project has also provided economic and quality of life benefits to area residents as well.
Economically, while the Mission Reach cost over $271 million to construct, over $600 million of new development has already been built along the project in less than a decade since its completion. Upwards of another $1 billion of development investment is anticipated to come to this area over the next ten years. This development is benefiting local property and sales tax collections, and most of this new development came to this section of the river because the public infrastructure investment in the Mission Reach served as a catalyst.
From a quality-of-life perspective, the Mission Reach project increased recreation opportunities along the river connecting the economically successful downtown River Walk to a historically underserved area of the city. Over sixteen miles of hike and bike trails were installed for pedestrians and bicyclists to enjoy and close to eight miles of paddling trail is now available for canoes and kayaks. Improvements to aquatic and riparian habitat are increasing the numbers of native wildlife species allowing fishermen, birdwatchers, and other nature enthusiasts more opportunities to enjoy wildlife in an urban area. Other quality of life benefits related to these recreational access improvements are bit more difficult to quantify, but no less important to mention. These benefits include the improved health of area residents who now have access to safe, outdoor green space to recreate and the environmental lift brought about by the ecosystem restoration. (See Figure 7.)
Overall, Mission Reach usage is trending up, which is a good indicator that citizens are getting outside and utilizing the nature-based and cultural park resources. Additionally, the uncertainty brought about by COVID-19 has caused anxiety, impacted plans, and altered lives in one way or another. For many, the tranquility of the outdoors has provided an escape from the stress of the current times. More people have been seen enjoying a walk, run, bike ride, fishing, or paddle along the San Antonio River. Early in the pandemic, trail counters along the Mission Reach registered nearly 124,000 hits (April and May 2020). That equates to over 7,000 more users on the trails each week as compared to this same period in 2019, which is an 83% increase! Overall, in 2020, nearly 560,000 visitors were counted using the Mission Reach. COVID-19 has reminded us that our creeks, rivers, parks, and green spaces are woven into our life as places that we need for personal physical and mental wellbeing as well as our community’s economic strength.
Figure 7. The Mission Reach has become a popular destination for locals and visitors to enjoy the restored native habitat along the San Antonio River.
Advancement of Public’s Understanding of Geology and Engineering Geology
As mentioned, the Mission Reach’s ecosystem restoration is already establishing itself well, and the average visitor does not see or understand the level of engineering that was used to build this project. However, the state-of-the-art engineering that went into designing and construction the Mission Reach is not remaining “hidden.” The River Authority has hosted visitors from around the world who travel to San Antonio to learn about
the River Walk, and specifically the Mission Reach project. As cities around the world seek to restore their rivers, the Mission Reach project is serving as a national and international model for urban ecosystem restoration.
In addition to hosting visitors from around the world, River Authority staff have presented information about the Mission Reach at global conferences, including: • The 2020, 2017, and 2014 International Riversymposium (multiple locations in Australia) • The 2020, 2018, 2015, and 2012 River Rally (multiple locations across the United States) • The 2019 Rivers and Mountains Conservancy Urban Rivers
Summit (Los Angeles) • The (2018) 9th Wuxi International Sister Cities Forum, a trip that also had staff meeting with officials in Nanjing and
Suzhou, China • The 2015 Mizbering World Conference in Osaka, Japan • The 2012 World River Forum in Deagu, South Korea • The 2012 World Canals Conference & World Canal Cities
Expo in Yangzhou, China • The 2010 Joint Workshop of the Ministry of Environment &
Clean-Up and Basin Management—Relevance for the Ganga in New Delhi, India, a trip that also had staff meeting with officials in Chennai.
Finally, River Authority educators use the Mission Reach to teach local school children about a variety of river and environmental related subjects. Pre-pandemic, the River Authority hosted 100 field trips per school year along the Mission Reach at Confluence Park, which was built to work with the environment by utilizing unique design principals that catch, collect, and use the rainwater that falls on the property. Confluence Park is also the place where River Authority educators inspire actions for healthy creeks and rivers through the interpretation of the park’s dynamic features and nature-based programming. Being adjacent to the Mission Reach, Confluence Park allows educators and students to walk along the banks of the river through part of the massive and scenic ecosystem restoration project. (See Figure 8.)
Figure 8. River Authority staff provide Science, Technology, Engineering, the Arts, and Mathematics (STEAM) educational lessons along the Mission Reach.
Enhancement of Local Cultural and Historical Understanding
In 2015, the United Nations Educational, Scientific and Cultural Organization (UNESCO) inscribed the San Antonio Missions as a World Heritage Site thus recognizing their worldwide significance. Both the historical and cultural importance of the San Antonio River as well as the Mission Reach project were mentioned in the material supporting the World Heritage Status nomination. The adopted UNESCO Statement of Outstanding Universal Value acknowledges the five missions were selected based on their geographical and functional relationship in the San Antonio River Basin and that the San Antonio River continues to play an important role in connecting the missions and providing an essential buffer to help ensure the integrity of the San Antonio Missions World Heritage Site.
When recreating along the hike and bike trail of the Mission Reach section of the San Antonio River Walk, visitors can use the “Mission Portals” to connect from the river to four of San Antonio’s World Heritage Mission Sites—Mission Concepción, Mission San José, Mission San Juan, and Mission Espada. These connections feature historic and artistic interpretations of the story of the missions and highlight their social and cultural importance to the area. Project planners worked closely with the National Park Service to ensure that there was a seamless transition between the Mission Reach and the San Antonio Missions National Historical Park, which is now a World Heritage site. Visitors can now experience the rich history of the area, which reinforces the importance of the river to the missions and encourages visitors to circulate between the missions and the river.
Summary
A beautiful, healthy river, breathtaking landscapes, grand artwork, and internationally recognized National Parks are just a snapshot the Mission Reach section of the San Antonio River Walk. By design, the Mission Reach looks much different than the historic San Antonio River Walk and the Museum Reach. The Mission Reach is a global example of urban ecosystem restoration. The fluvial geomorphic principles coupled with Hydraulic and Hydrology modeling helped the project achieve its high aims to restore the San Antonio River while maintaining flood control and reducing erosion. The project has improved the San Antonio River’s water quality, ecosystem function, and health. The result is a serene, natural landscape where visitors can enjoy the inherent beauty of the river unaware of the immense engineering that created the restored environment. (See Figure 9.)
The AEG Outstanding Environmental & Engineering Geologic Project Award for the Mission Reach is an honor for the engineering and scientific staff of the San Antonio River Authority as well as from Bexar County, City of San Antonio, USACE, Jacobs, and Zachry Construction Corporation. The Mission Reach is an enormous collaborative effort, and all involved should be commended for their stellar accomplishment.
The Mission Reach project is a testament to sound scientific tenets and innovative engineering design.
Steven Schauer, Director of External Communications for the San Antonio River Authority, has been with the agency since January 2007. Schauer oversees the Government Affairs Department and Brand & Public Communications Department. His work includes developing and implementing the strategic direction for the agency’s communication and outreach activities, acting as the Authority’s spokesman, coordinating local, state, and federal legislative and policy agendas, and directing the educational outreach programs. He also manages the River Authority’s national and international relations.
Under Schauer’s leadership, the River Authority has received over 75 professional awards and recognitions for the high-quality communication products produced by and/or for the agency. The River Authority’s reputation as an innovative and successful watershed management organization has grown significantly, both domestically and internationally, during his tenure. As a result, the agency regularly hosts domestic and foreign visitors; Schauer leads most of these interactions, which also includes opportunities to travel and present at global river conferences.
At the invitation of the World Bank, Schauer traveled to New Delhi, India to present at the 2010 Joint Workshop of the Ministry of Environment & Forest and the World Bank titled Global Experiences in River Clean-Up and Basin Management – Relevance for the Ganga. During that trip, he also traveled to Chennai to meet with local officials regarding efforts to clean the Cooum River. Schauer was a presenter at the 2012 River Rally in Portland, Oregon, and the 2012 World River Forum in Deagu, South Korea. He was a Keynote Speaker at the 2012 World Canals Conference & World Canal Cities Expo in Yangzhou, China. In 2015, Schauer was a Keynote Speaker at the Mizbering World Conference in Osaka, Japan. At the 2017 International RiverSymposium in Brisbane, Australia, Schauer was a speaker at the conference, and he had the honor of accepting the 2017 International Riverprize, which was awarded to the San Antonio River. In 2018, Schauer was a Keynote Speaker at the 9th Wuxi International Sister Cities Forum in Wuxi, China, a trip that also had him meeting with officials in Nanjing and Suzhou. Schauer was a presenter and panelist at the Rivers and Mountains Conservancy Urban Rivers Summit held in Los Angeles, California in 2019. During the 2020 International RiverSymposium, Schauer was asked by conference organizers, International RiverFoundation, to participate on two panels.
Schauer has also served as the executive producer and cowriter of the River Authority’s award winning 75th anniversary documentary about the San Antonio River and executive producer and director of the award-winning documentary about the Mission Reach Ecosystem Restoration and Recreation Project. He was also the executive producer, writer, director, videographer, and editor of a film about paddling the San Antonio River from San Antonio to Seadrift—a 200+ mile paddling trip he had the immense pleasure of leading.
Schauer has a Master of Public Affairs degree from the LBJ School of Public Affairs at the University of Texas at Austin (2001) and a Bachelor of Science in Environmental Science from Incarnate Word in San Antonio (1994).
Schauer has represented the River Authority on numerous boards and committees, including serving on the board of the San Antonio River Walk Association and Hot Wells Conservancy and on the Visit San Antonio Tourism Committee.
