Lower Stillaguamish Floodplain

Floodplain
Floodplains occur where large rivers and streams meander in their own sediments

Salish Sea References

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The Lower Stillaguamish is a focus area of the Snohomish Sustainable Lands Strategy. Salmon Recovery planning organized at the Stillaguamish Watershed Council. The lower valley has very productive farmlands, economically and socially connected to seed production networks centered in the Skagit Delta. There are si The City of Stanwood is the social center of the lower valley, and Lower Stanwood is below sea level and protected by sea dikes. The Stanwood causeway connects Camano Island to the mainland.

Notes[edit]

Stillaguamish Delta is generally considered part of the "Lower Stillaguamish". Tidal influence extends up river part way to Silvana.
Church Creek Watershed and Pilchuck Creek Watershed are the major tributaries from the north.
Portage Creek Watershed and the Cougar Creek Watershed enter from the south.
The Interstate 5 causeway provides a natural hydrologic boundary between the lower valley and the upper valley.
The Upper Stillaguamish Floodplain lies upstream between I-5 and the confluence of the forks.
This is among the most productive farmland in Western Washington.
2014 Article in Everett Herald describing City of Stanwood response to high flood risk.
The Visser Dairy has partnered with the Stillaguamish Tribe to test an innovative manure processing technology (advanced distillation) to replace manure lagoons.
- Article in Stanwood Camano News

Efforts[edit]

Stillaguamish Valley Protection Initiative - involves TNC, Forterra and Washington Farmland Trust collaborating to protect farmland in support of the Snohomish Sustainable Lands Strategy.
Stillaguamish Delta Dredged Sediment Re-use - an initial look at using reused dredge material to build up sediment on the eroding Stillaguamish Delta
Stillaguamish Delta Restoration Pre-design - a monitoring effort by TNC and WDFW to evaluate sediment distribution across the delta face after the Port Susan Restoration
Port Susan Restoration - An initial restoration effort by TNC on 150 acres of difficult to drain delta farmland
Leque Island Restoration - The flooding of the 300 acre Leque Island by WDFW in response to restoration needs and failing dike infrastructure.
Zis a Ba Restoration - An 80 acre restoration on the "Matterand property" purchased by the Stillaguamish Tribe
Stillaguamish Valley Protection Initiative - a local initiative to protect open space, agriculture, water quality and salmon habitat in the Stillaguamish Valley.
Snohomish County is leading a Pollution Identification and Control program to manage fecal and nutrient pollution of shellfish beds from agricultural operations.
The Snohomish Agricultural Resilience Plan considered saltwater intrusion under sea level rise to inform future pathways for management of the lower valley.
Floodplains by Design has provided two funding packages for a cluster of actions in proposals coordinated by the Stillaguamish Tribe including a manure processing system.

Planning Documents[edit]

Stillaguamish River strategies primarily build on Recovery planning and TMDL temperature analysis.

STAG 2000 provides the technical basis for salmon recovery planning.
USACE 2000 describes an Army Corps General Investigation of restoration in the Stillaguamish.
Pelletier & Bilhimer 2004 describes assessment of temperature violations under Clean Water Act
Turner et al 2004 describes a council approved flood management strategy.
SIRC 2005 is the published Stillaguamish Salmon Recovery Plan.
Lawrence 2006 stillaguamish temperature TMDL strategy describes an implementation strategy to resolve findings of Pelletier & Bilhimer 2004.
Griffith & Fuller 2012 describes long range salmon recovery targets in the Stillaguamish Delta.
Hall et al 2014 describes model analysis of factors correlated with peak flow and low flow trends.
Walter et al 2014 describes a strategy for managing peak flows for chinook survival.
Leonetti 2015 augments the implementation strategy through identification of cold water refugia.
STAG 2015 describes an acquisition strategy for restoration of floodplain processes.
Hurner et al 2016 describes the LIO strategy for both Snohomish and Stillaguamish basins.
Snohomish County has completed a reach-scale plan, aggregating knowledge about the lower Stillaguamish.

Map Resources[edit]

File:Lower Stillaguamish.pdf - a large map of the lower stillaguamish
File:Lower Stillaguamish DEM.pdf - a similar map with a elevation model of the floodplain showing river evolution
File:Lower Stillaguamish Agriculture.pdf - a map showing 2011 agricultural land use and acreage.
The Resource Lands Protection Initiative is an effort to define a shared land protection strategy that benefits both fish and agriculture and is centered in the Lower Stillaguamish.
File:Lower stillaguamish floodplain parcels.pdf is a draft map produced to support planning
Ecosystem Management Draft Map Set - the following maps sets were developed to support planning discussions about how to fully implement Salmon Recovery planning in the Stillaguamish River floodplain, while also protecting agricultural landscapes and production. The floodplain landscape was divided into four units, to improve resolution. Maps are 24 x 36 inch 300 ppi PDF, approximately 20-25 MB each.
- The Parcel Series shows property boundaries over aerial photographs, with depressions, topographic flow pathways, and watercourses.
- The Elevation Series shows water features over a digital elevation model for observing more details of floodplain scrolling and restoration opportunities.