Upper Truckee Marsh Sewer Marsh Restoration
In the fall of 2016, the California Tahoe Conservancy (CTC) selected Northwest Hydraulics (NHC) as the lead design engineer for this comprehensive, complicated, and extremely important restoration project. WBS, along with Balance Hydrologics, was selected as a critical team member to assist with development of associated plans and specifications, and details, emphasizing biotechnical (vegetative) methodologies. WBS was part of the original team (Global Environmental) and in 1995 and 1996 identified and mapped the plant communities in the project area; WBS has extensive knowledge of this ecosystem and appropriate restoration methodologies.
From the CTC web site. ‘In the last 150 years development has eliminated more than half of the original 1300-acre Marsh. The Conservancy has acquired 600 acres to restore the river’s natural cleansing function and subsequently increase habitat quality for plant, wildlife, and fish species”.
WBS joined team members in 2017 for a late season but essential site survey to evaluate conditions and the preferred alternative, evaluating information gaps, methods, and details. In early 2018, in another year of high lake levels, the team conducted thorough analyses of soils, vegetation, and sod handling, essential for design of the pilot channels.
In 2020 WBS participated in the completion of the 100% design set of plans and specifications for this challenging project that includes several phases of permitting, design, and construction. Fundamental concepts for restoration design emphasize biotechnical engineering, including salvage and re-use of on-site materials such as sod, willows, and topsoil, limited maintenance (irrigation), and enhancement of natural succession in part through improvement of wildlife habitat.
WBS oversaw components of construction in the summer and fall of 2020 and 2021. Construction of the pilot channels was completed in 2020. In 2021 construction included the new bulkhead at the Sailing Lagoon, fill and wetland restoration at the former Sailing Lagoon and the dune/interdune area, and noxious weed control. Restoration plantings will continue in the spring, summer, and fall of 2022 at the restored marsh, and new grading will connect the river with the restored wetlands in the fall of 2022. Plantings in the fall will conclude with the restoration of the access roads. Two years of post-construction maintenance will follow, concluding in the fall of 2024. This project will be featured during the Western Chapter of the IECA field tour August 4 and 5, 2022.
Traducción Española:
En el otoño de 2016, como parte de un equipo de especialistas compuesto de ingenieros, hidrólogos, y bio-ingenieros de amplia experiencia en la restauración de cuencas y ríos, WBS nuevamente inició (después de una ausencia de 17 años) investigaciones científicas y diseños de restauración en el tramo más importante de la zona alta del río, Truckee Upper Truckee River, Lake Tahoe, California. Se determinó que este tramo es la fuente mayor de sedimentos al sistema hidráulico y al lago.
Como explica la página de la agencia estatal (CTC, por sus siglas en inglés) que se responsabiliza con el manejo del proyecto. Durante aproximadamente los últimos150 años el rio ha experimentado varias alteraciones, sobre todo en la cuenca inferior, cambios de drenaje, presas, ganadería, etc., todo provocado por el hombre. Desde los años sesenta, debido al desarrollo urbano, el medio ambiente ha deteriorado con una pérdida de más de la mitad de los 1.300 acres de humedal.
En el verano y otoño del 2017 realizamos estudios esenciales, aunque limitados por falta de fondos, durante la fase final del contrato que fue a un nivel del 50% de diseño, lo cual se incluyeron nuevos canales, relleno del tramo existente, y aumento de la zona de inundación.
