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San Antonio river authority takes leadership role: sustainability through stream restoration.

In 1937, the Texas Legislature created the San Antonio River Canal and Conservancy District (the predecessor agencv to the San Antonio River Authority) to establish navigation from the Gulf of Mexico to the City of San Antonio. While there is no navigation canal today, and most people know San Antonio for the River Walk, the San Antonio River Authority (SARA) has a great legacy. SARA has constructed and maintains hundreds of millions of dollars in flood control infrastructure, including flood control gates, 31 miles of flood control channels, 40 earthen dams, and two flood control tunnels. Additionally, in support of its mission to improve water quality. SARA conducts intensive water quality monitoring coupled with targeted mitigation projects, maintains a top-notch database of water quality data, and provides wastewater collection and treatment services to a growing section of the San Antonio community

A push toward sustainability

In the last decade, SARA moved to a new approach to achieving sustainability within the San Antonio River Basin. The push started through a community vision, called the San Antonio River Improvements Project (SARIP), which aims to extend the River Walk north, through a segment named the Museum Reach, and to restore eight miles of channelized river to the south, through a segment named the Mission Reach (figs. 1,2, and 3). SARA worked with stakeholders to initiate planning, currently manages the construction, and has committed to ongoing operations and maintenance of the finished project. The SARIP is a $358.3 million investment in promoting sustainable development by balancing economic, social, and environmental interests. This sustainability push has transformed the agency, which now employs natural resource specialists, stream restoration specialists, education specialists, biologists, chemists, and engineers who work together in restoring degraded channels and promoting habitat preservation, rehabilitation, and restoration.

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In 2011, two of the eight miles of the Mission Reach were completed through a cooperative project with the U.S. Army Corps of Engineers, Bexar County, SARA, the City of San Antonio, and the San Antonio River Foundation. The project was designed using fluvial geomorphologica! principles and creating a riffle-pool-run sequence of features aimed at balancing sediment transport and creating aquatic and riparian habitat. These goals were achieved while adding recreational amenities such as picnic benches, pavilions, and hike and bike trails to complement over 450 acres of restored habitat that includes native grassland and over 23,000 native trees and shrubs. All these amenities were added while maintaining the flood-carrying capacity of the flood control channel.

One good thing leads to another

The experience gained from the Mission Reach project was used by our diverse team in learning natural channel design (NCD) techniques for restoring streams. SARA staff and consultant teams were trained in Rosgen principles and by other stream restoration experts at North Carolina State University, Michael Baker Jr., Inc., and Stantec. This knowledge was then applied to a pilot project along East Salitrillo Creek, east of San Antonio, in partnership with the Judson Independent School District (JISD) (figs. 4, 5, and 6).

East Salitrillo Creek was an optimal location for the demonstration of NCD techniques. The stream was laterally and vertically unstable due to increased urban development in its watershed and the removal of deep-rooted vegetation. Consequently, the stream was degraded in habitat value and stream function, and it posed a threat to the infrastructure of the high school campus on which the segment was located. Fortunately, the stream's floodplain was entirely contained within the school's athletic fields, making alterations to the stream course and to the frequency of overbank events possible without negatively impacting infrastructure. JISD was interested in partnering with SARA to repair the stream as well as to realize numerous opportunities for student and community education due to the inherently multidisciplinary approach associated with NCD and the variety of sustainable components incorporated into the project.

Construction began in January 2011 and was completed within ten weeks. The project integrates a variety of in-stream structures, such as cross vanes, J-hooks, and constructed riffles, that provide grade control, stream stabilization, and aquatic habitat. Bioengineering techniques were also used, including the use of toe-wood, root wads, and willow cuttings. Following the earthwork, over 50 species of native plants were established, including nine species of trees and shrubs, resulting in a significant improvement in riparian plant diversity. Project vegetation was designed to meet the site conditions as well as the specific requirement of the district that there not be a tall, dense vegetative screen along the stream. The design emphasized the use of deep-rooted native emergent and water's edge species to maximize rapid growth in vulnerable areas of the stream and in locations intended for water quality improvement. A reuse irrigation system was installed to accelerate vegetation establishment and protect the designed channel morphology, which was critical for the project, as the planting occurred during the spring of what became one of Texas' worst droughts on record.

... and another

The positive impacts of the East Salitrillo Creek project on the environment and the community were numerous and diverse. Most importantly, the channel stability issues were addressed by reshaping the stream channel, adding in-stream structures, and planting deep-rooted herbaceous and woody vegetation. Stabilization reduces erosion, and it minimizes the need for maintenance to dredge aggraded sediments downstream and to protect endangered infrastructure. The restoration efforts also anticipate improved water quality in the stream by treating stormwater runoff from the campus through the incorporation of bioswalcs at two stormwater outfalls and through the construction of an ephemeral pool at another outfall within the site. Increased channel morphological diversity and the diversification of native plants on-site provide a significant improvement to habitat for aquatic and riparian species. Finally, the project provides myriad opportunities for education and outreach of SARA staff, JISD students, and the community at large.

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SARA's next steps are to fully integrate NCD and stream restoration with urban planning and development as a best management practice in partnership with local government agencies. Maximized sustainable results will be achieved by pairing the in-channel NCD efforts with low-impact development within the watershed. In addition, design guidance and characterization of the streams in the San Antonio River Basin will be developed to assist local designers with incorporating appropriate NCD techniques in private and public development projects.

ASABE member Russell Persyn, manager of Watershed Engineering; Lee Marlowe, natural resource specialist; Maura Dudley, education coordinator; Albert Vega and Robert Jenkins, engineers; Steve Lusk, manager of Environmental Sciences; Luke Habenicht, intergovermental coordinator; ASABE member Steve Raabe, director of Technical Services; and Mike Gonzales, deputy director, all at the San Antonio River Authority, San Antonio, Texas, USA; rpersyn@sara-tx.org.
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Author:Persyn, Russell; Marlowe, Lee; Dudley, Maura; Vega, Albert; Jenkins, Robert; Lusk, Steve; Habenicht,
Publication:Resource: Engineering & Technology for a Sustainable World
Geographic Code:1U7TX
Date:Mar 1, 2012
Words:1112
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