April 28, 2016 - Update on the Arroyo Seco Ecosystem Restoration Feasibility Study presented by Priyanka Wadhawan, P.E. to the Council of Arroyo Seco Agencies
The US Army Corps of Engineers is studying a 10 mile reach for habitat restoration opportunities (e.g. aquatic wetlands, removal of concrete, parallel natural channel, etc.); the 10 miles has been divided into 8 reaches
Hydraulic and structural modeling has been completed. Biologists are now performing habitat modeling. An overall cost modeling will follow.
The Corps anticipates completion of their draft study, the Tentatively Selected Plan, by July 2016. It will encompass their assessment of all the reaches.
The Tentatively Selected Plan will then be critiqued by USACE headquarters (Washington) in August 2016.
Alternatively, a local plan can be used instead of the Tentatively Selected Plan (this discussion would occur after August).
Coordination and Feedback
LA County Flood Control District will coordinate with the Corps to ensure efforts with the County's Load Reduction Strategy coincide with the Corps' Study.
The Arroyo Seco Ecosystem Feasibility Study is a partnership between the County of Los Angeles Department of Public Works and the U.S. Army Corps of Engineers with the assistance of governmental agencies and environmental organizations within the watershed.
This study was originally intended to be a three year study to investigate long-term solutions for water resources and environmental restoration issues within the Arroyo Seco Watershed.
In 2001 the US Army Corps of Engineers (USACE) initiated a watershed study of the Arroyo Seco. The Reconnaissance Study Section 905(b) (WRDA) Analysis, completed in November, 2002, determined: "The future or without project condition of the Arroyo Seco Watershed is a serious concern to the public and the LACPW (Los Angeles County Public Works). The limited and fragmented open space and habitat along the Arroyo Seco corridor, especially in the lower watershed, will result in the continual decline of the environmental and aesthetic quality in the Los Angeles Region. In addition, natural groundwater recharge in the watershed is an important component to water conservation in the Raymond Basin. It is the goal of the watershed study to develop the necessary baseline data and analytical tools, and a realistic set of objectives that will encourage management decisions that help reverse negative trends or enhance positive trends to maintain or improve the health of the watershed. Without environmental restoration in the Arroyo Seco Watershed, the problems identified by the public and local sponsor will continue unabated, these problems include:
The Reconnaissance Study identified a strong federal interest in the Arroyo Seco watershed. "In accordance with current administration policy, there is a federal interest in watershed based studies that provide a holistic approach to evaluating water resource problems and opportunities leading to the development of a watershed management plan that effectively balances the need for sustainable economic development with the need for protection of watershed natural resources. Since environmental restoration is a likely output of the watershed study with a high budget priority and environmental restoration, water quality, flood control, and other related issues are integral to any comprehensive watershed plans that would be evaluated in the feasibility phase, there is a strong Federal interest in developing a feasibility study for the Arroyo Seco Watershed. There is also incidental Federal interest in other benefits resulting from the study such as recreation and water conservation/supply that could be developed within existing policy. Based on the preliminary screening of alternatives, there appears to be potential watershed plan alternatives that would be consistent with the U.S. Army Corps of Engineers policies, benefits, and environmental impacts."
In May 2005 the USACE released the Project Management Plan for the study with a revised, trimmed budget of $2.7 million dollars and a scope of work that would develop a comprehensive watershed management plan including implementation projects for the entire watershed from the San Gabriel Mountains to downtown Los Angeles. The plan will include water resources, ecosystem restoration, flood management and recreational elements. Key watershed functions and purposes to be studied include:
In August 2011 the Corps released the Feasibility Scoping Meeting Documentation, which details environmental conditions in the Arroyo Seco and identifies sites for potential projects. This document is a key step toward completion of the Arroyo Seco study.
The Los Angeles County Flood Control District in May, 2013 urged the US Army Corps of Engineers to accelerate and complete the Arroyo Seco Watershed Feasibility Study. On May 8th Gary Hildebrand, Assistant Deputy Director of the County Department of Public Works wrote to Colonel R. Mark Toy, Commander and District Engineer of the Corps, "The LACFCD is willing to accelerate funding to facilitate completion of the Study" and goes on to state, "It is critical that we finalize this effort and move forward with the feasibility portion of the Study, which will allow us to identify potential projects that will benefit the environment and improve the quality of life for the community."
You can view the Flood Control District's letter here: Accelerate Arroyo Seco Study