The authority for the Skagit River General Investigation is derived from Section 209 of the Flood Control Act of 1962 (Public Law 87-874). The authorizing language includes the following: Flood Control Act of 1962, Section 209: “The Secretary of the Army is hereby authorized and directed to cause surveys for flood control and allied purposes, including channel and major drainage improvements, and floods aggravated by or due to wind or tidal effects, to be made under the direction of the Chief of Engineers, in drainage areas of the United States and its territorial possessions, which include the following named localities: Provided, That after the regular or formal reports made on any survey are submitted to Congress, no supplemental or additional report or estimate shall be made unless authorized by law except that the Secretary of the Army may cause a review of any examination or survey to be made and a report thereon submitted to Congress, if such review is required by the national defense or by changed physical or economic conditions: Provided further, That the Government shall not be deemed to have entered upon any project for the improvement of any waterway or harbor mentioned in this title until the project for the proposed work shall have been adopted by law: …” “…Puget Sound, Washington, and adjacent waters, including tributaries, in the interest of flood control, navigation, and other water uses and related land resources.”
The study area is the Skagit River Basin (Basin). The Basin is located in the northwest corner of Washington State, approximately 60 miles north of the City of Seattle. The Basin has a total drainage area of 3,115 square miles and extends about 110 miles in a north-south direction. The Skagit River (River) originates near the 8,000-foot level of the Cascade Mountains in British Columbia, Canada and flows south and then west to the Skagit delta where it discharges through two distributaries, the North Fork and South Fork, to Puget Sound. The upper Basin is mountainous, largely forested and sparsely populated. The lower Basin or Skagit River Delta (roughly from the town of Sedro-Woolley at River Mile 24 to the mouth) is largely comprised of agricultural lands, some of the most productive in the state. Extensive diking of the lower river, dating back to the last part of the 19th century, has allowed the Skagit floodplain to be farmed and developed for residential, commercial and industrial purposes. This development has resulted in alteration of natural riverine processes.
The project area encompasses the Skagit River watershed and the Skagit River floodplain from the Seattle City Light’s Ross Dam reservoir (Ross Lake) to Puget Sound, a total of approximately 150 river miles. The Upper and Lower Baker Dams on the Baker River, tributary to the Skagit River, are in the project area. The Sauk-Suiattle River and the Cascade River tributaries have Wild and Scenic status; therefore are not part of the study area. Study measures and alternatives are largely focused in the most the most densely populated and developed areas of Skagit County, including the cities of Sedro-Woolley, Burlington, Mount Vernon, and La Conner. The floodplain is bisected north-south by Interstate 5 and the Burlington Northern Santa Fe Railroad. Both the Basin and River are habitat for a number of Endangered Species Act (ESA) listed species such as Puget Sound Chinook Salmon (Oncorhynchus tshawytscha) and the Puget Sound Steelhead (Oncorhynchus mykiss).
Problem: The Skagit River Basin is subject to rain floods and related snowmelt runoff flooding that typically occurs from October – March. This flooding results in damages to infrastructure; residential, commercial and industrial structures; agricultural areas; and is a threat to life safety. Existing flood control systems, including locally owned levees and flood control storage in non-Federal hydropower projects, provides a limited level of flood risk management to developed areas that is not acceptable to the local communities in the Basin.
Opportunity: Reduce flood risk and life safety risk in the Skagit River Basin from overland flow resulting from October to March rain floods.
Goal: The goal of the Skagit River General Investigation is to identify a plan that reduces flood risks and contributes to national economic development consistent with protecting the Nation’s environment, pursuant to national environmental statutes, applicable executive orders, and other Federal planning requirements.
Objective: Reduce flood damages in the Skagit River Basin over the 50 year project life from 2020 to 2070.
Objective: Reduce threats to life safety in the Skagit River Basin over the 50 year project life from 2020 to 2070.
Universal Constraints:
- USACE shall ensure that the project would not jeopardize the continued existence of any endangered species or threatened species (including three ESA-listed species of salmonids) or result in the destruction or adverse modification of the habitat of such species.
Study-specific Constraints
- Wild and Scenic River status of the upper Skagit, Cascade, and Sauk-Suiattle Rivers precludes formulation of flood risk management measures that would permanently harm the rivers’ free flowing condition for these areas.
- To comply with Skagit County Code, the project should avoid direct and indirect loss of agricultural lands wherever there is a practicable alternative.