Abstract Title

Session S-05E: Managing Floodplain Rehabilitation Success to Inform Decision Making: A Case Study from Hansen Creek, Skagit County

Keywords

Habitat

Location

Room 613-614

Start Date

1-5-2014 10:30 AM

End Date

1-5-2014 12:00 PM

Description

Since 1955, Skagit County has been involved in flooding and sediment issues concerning Hansen Creek. Some form of sediment removal has been the response to localized flooding in the lower portion of the Hansen Creek Watershed. In 1982, at the request of flooded landowners, a Sub-Flood Control Zone was formed. Skagit County will present data on the costs of maintenance dredging and responding to emergency flooding over the 1997-2007 10-year period and also savings to both the County and landowners from the time when the floodplain project was implemented. Since the completion of the Hansen Creek Alluvial fan project in 2010 there has been no expenditure of County assessment funds toward on-the-ground Hansen Creek flood control or channel maintenance. In 2010 the Hansen Creek Sub-Flood Control Zone was abolished mainly due to the establishment and success of the Hansen Creek alluvial fan. The success of the Hansen Creek alluvial fan project in attenuating the amount of sediment delivered downstream and in reducing the frequency, height, and duration of downstream flooding has resulted in collaboration between downstream landowners, Skagit County, and the Skagit River System Cooperative to develop additional floodplain rehabilitation. This downstream reach of Hansen Creek is currently a plane bed channel isolated from its floodplain by berms. The channel is almost entirely straightened and is devoid of any instream features (i.e. woody debris, boulders). Skagit County will highlight, based on the 2002 Hansen Creek Watershed Management Plan, the actions and modeling recommendations being advanced to further mitigate flood impacts in the lower Hansen Creek Watershed and restore natural resource benefits to the ecosystem.

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May 1st, 10:30 AM May 1st, 12:00 PM

$aving with Fish, Floodplains & Farmers: Expanding the Reach

Room 613-614

Since 1955, Skagit County has been involved in flooding and sediment issues concerning Hansen Creek. Some form of sediment removal has been the response to localized flooding in the lower portion of the Hansen Creek Watershed. In 1982, at the request of flooded landowners, a Sub-Flood Control Zone was formed. Skagit County will present data on the costs of maintenance dredging and responding to emergency flooding over the 1997-2007 10-year period and also savings to both the County and landowners from the time when the floodplain project was implemented. Since the completion of the Hansen Creek Alluvial fan project in 2010 there has been no expenditure of County assessment funds toward on-the-ground Hansen Creek flood control or channel maintenance. In 2010 the Hansen Creek Sub-Flood Control Zone was abolished mainly due to the establishment and success of the Hansen Creek alluvial fan. The success of the Hansen Creek alluvial fan project in attenuating the amount of sediment delivered downstream and in reducing the frequency, height, and duration of downstream flooding has resulted in collaboration between downstream landowners, Skagit County, and the Skagit River System Cooperative to develop additional floodplain rehabilitation. This downstream reach of Hansen Creek is currently a plane bed channel isolated from its floodplain by berms. The channel is almost entirely straightened and is devoid of any instream features (i.e. woody debris, boulders). Skagit County will highlight, based on the 2002 Hansen Creek Watershed Management Plan, the actions and modeling recommendations being advanced to further mitigate flood impacts in the lower Hansen Creek Watershed and restore natural resource benefits to the ecosystem.