Beginning in 2001, Tillamook County, in concert with numerous partners, purchased 377 acres from three private landowners specifically for habitat restoration. Tillamook County holds title to the land; the Wetlands Management Plan, developed by multiple stakeholders, governs its use. The County’s efforts to restore the 377 acres stalled when hydraulic analyses concluded that full restoration of the entire site would cause unacceptable flood level increases within the City of Tillamook’s Highway 101 business district. The study concluded partial restoration of the 377 acres was possible, but flood level reductions were minimal.
In 2006 and 2007, Tillamook County suffered large floods and extensive damages. After the 2006 flood, Governor Ted Kulongoski established the flood mitigation effort as an “Oregon Solutions” project. The Oregon Solutions process provides a structure and process for public and private sectors to collaborate in addressing technically and politically challenging needs. Subsequently, a 34-member Project Team and 15-member Design Team of federal, state, and local government agencies as well as community groups, business organizations, and individuals was assembled.
Northwest Hydraulic Consultants Inc. (NHC) in conjunction with HBH Engineering Consultants was selected by the Design Team to analyze flooding on the Wilson River floodplain and develop solutions to reduce flood levels. After an alternatives analysis and several rounds of revision and input from the Design Team, the preferred alternative Project Exodus was selected. Project Exodus consisted of three separate, independent elements that addressed flood level reduction in the lower Wilson River floodplain, the Southern Flow Corridor (SFC) being one of them.
The Design Team decided to pursue implementation of the SFC as a priority. Among the reasons was that the SFC provides by far the largest benefits in flood damage reduction, both in terms of flood levels and area benefitted, and that the SFC had potential significant funding available in the form of FEMA alternate project funds through the Port of Tillamook Bay. At the same time, concerns were raised with the original SFC scope in regards to the conversion of agricultural lands to restored marsh as a result of the proposed levee removals. NHC was then directed to evaluate the hydraulic impacts of the SFC on its own as a standalone project, and to investigate alternatives that minimized the amount of agricultural lands that might be lost. NHC presented its findings in June 2010, which demonstrated that the SFC did indeed provide flood level reduction benefits on its own, and that alternatives were available that allowed some of the originally targeted agricultural lands to remain as such rather than being acquired and converted to salt marsh.
With this information, Tillamook County began real estate discussions with three landowners whose properties were required to be purchased outright for the project. Leo Kuntz of Nehalem Marine began discussions with adjacent landowners and those whose lands were identified as needing dike modifications but not acquisition. As a result of these discussions, the project was slightly modified and renamed the Southern Flow Corridor – Landowner Preferred Alternative (SFC-LPA), meeting landowner desires and functioning as a natural overland path for Wilson River floodwaters.
NHC modeled this modification to ensure continued flood level reduction performance. In addition to its extraordinary habitat benefits, the SFC-LPA project was shown to be the most cost effective flood level reduction measure by creating a flow corridor from Highway 101 out to Tillamook Bay. At the May 13, 2011 OS Design Team meeting, this modification was approved, and subsequently approved by the Project Team.