Southern Flow Corridor Landowner Preferred Alternative
Sadri Property Remediation

 

Spring 2016 Project Update: A modification to the existing cooperative agreement for the Southern Flow Corridor Restoration project was completed in late August 2015, which added remediation of the Sadri property.  Remediation and cleanup activities will be conducted at the Sadri parcel prior to full tidal restoration of the larger Southern Flow Corridor site.  Pre-remediation site preparation and vegetation clearing has been completed.  All permits have been secured.  The contract RFP has been released, bids have been submitted, and a final contract is being prepared.  On-the-ground work will be initiated in June, per allowable permit windows.  All work is anticipated to be completed by November 2016.  The funding will be billed and a summary report will be completed by December 2016.

 

Tillamook Southern Flow Corridor Project EIS

Proposed floodplain restoration protects farmland, reduces flood risk, and restores salmon in Tillamook County, Oregon

 

Background: An estimated 86% of the 6,035 acres of historic tidal wetlands in the Tillamook Bay estuary have been lost.* These tidal wetland habitats include forested and shrub tidal swamps and grassy tidal marsh. Remaining habitats also tend to be degraded and fragmented along outmigration corridors for salmonid species. This project will protect and enable restoration of an ecologically diverse site that spans a rapid transition zone, from freshwater spruce forest, tidally influenced freshwater wetlands, high salt marsh down to low marsh and intertidal mudflats. Removing the levees surrounding the site and along the sloughs will allow full connection with the Wilson and Trask Rivers and tidal influence within the site.  The 646-acre project area makes the project one of the largest tidal restoration efforts on the Oregon Coast. Of this area, 513 acres will be permanently protected in public ownership. The project will create a large scale, contiguous land block composed entirely of priority habitats and restore approximately 10% of historic tidal wetlands.  

 

Project Description: This project is located in Tillamook Bay, 45.4595, 1123.8475, and is 646 acres, of which 519 will be restored to full tidal inundation. Four acres of a 65-acre tract, located within the project boundary, consists of 65 acres, requires environmental cleanup.

 

Project Purpose: Cleanup/remediation on four acres will support the overall goals of the project to improve declining fish populations and provide for flood mitigation.

 

Species to benefit: Loss of estuarine rearing habitat has limited the production of five Tillamook Bay Basin salmonid stocks:  Oregon Coast Fall Chinook Salmon, Oregon Coast Coho Salmon, Oregon Coast Spring Chinook Salmon, Oregon Coastal Chum Salmon, and Oregon Coastal Cutthroat Trout. Some of the key factors affecting species survival in estuarine environments are related to their ability to access habitats and the quality of the habitats that they occupy. These, combined with the quantity of suitable habitat, play a large role in determining the magnitude of the production bottlenecks. Implementation of this project will directly benefit the aforementioned fish species by addressing these habitat-based factors (i.e. habitat access, quality, and quantity). The project will restore 519 acres of marsh and wetland fringe habitat by:  1) creating 14 miles of newly connected slough/channel habitat; and 2) creating new habitats, such as low salt marsh, through re-establishing natural hydrologic conditions. The project location is considered to be ideal, largely because it lies within the migration pathway of salmonid species that emigrate as juveniles from the Wilson, Trask, and Tillamook rivers, and is also within the potential home range of juveniles from other tributaries and rivers.

 

How will the project be evaluated for success? Under the guidance of the Monitoring Advisory Committee, the Institute for Applied Ecology and Confederated Tribes of Siletz Indians have developed an extensive monitoring plan. Monitoring will occur before and a minimum of six years after construction and evaluate the following parameters:  Vegetation, soils, groundwater levels, juvenile salmon use, flood levels, tidal hydrology, macroinvertebrates, water quality, channel morphology, sediment deposition, and blue carbon. Metrics to be evaluated:

1: Changes in vegetation communities.
2: Changes in wetland functions.
3: Changes in salmonid use and habitat quality.
4: Changes in flood levels.

 

This project addresses climate change strategies:

3.1 Take conservation action for climate-vulnerable species.
As with many coastal restoration projects, impacts of sea-level rise on long term project performance is potentially an issue. Sea-level rise projections are uncertain and given recent projections, it appears likely that sea-level rises will not be matched by overall Bay sediment accretion. From a habitat perspective, there will be a shift of habitat zones towards the upper Bay and project site. However, sediment accretion has been greatest in the highest portions of the Bay. Due to its location at the confluence of major sediment sources, this project is well suited to maximize accretion and, if not match sea-level rise, have a shorter response lag and hence be able to continue to provide functional habitat value long term. Since duration of inundation is a controlling factor for sediment deposition, diked sites will have little deposition because they have little inundation (compared to undiked sites). Thus, removing the levees that currently isolate the project area will facilitate natural marsh accretion and allow the site to keep pace with sea-level rise, fostering species’ resilience and adaptability.
 
3.2 Promote habitat connectivity and integrity.

This project restores and permanently protects over 500 acres of estuarine habitats on the Oregon Coast. The resultant large scale, contiguous land block restores approximately 10% of historic tidal wetlands at the confluence of three major rivers and supports a myriad of native flora and fauna species.
 
3.3 Reduce non-climate change ecosystem stressors.

The project designs allows for the project area to be self-sustaining with an improved ability to withstand or adapt to non-climate change stressors. These stressors include habitat loss and fragmentation, degraded water quality, and invasive species.
 
3.5 Conserve coastal and marine resources.

A recent Climate Leadership Initiative report states that sea-level rise in Oregon, driven by climate change, “will severely impact low-lying coastal areas”. TEP’s draft climate change report estimates that local sea-level rise has been approximately two millimeters (mm)/year. Projections indicate that by 2100, local sea-level rise will be approximately 62 centimeters (cm), with a possible range of 10-140 cm. It’s likely that Tillamook Bay will also experience more severe storms. Conserving and restoring wetlands adjacent to the Bay is likely to help mitigate sea-level rise and storm surge. The project’s location at the confluence of the three rivers ensures an abundant sediment supply that will reduce the possibility of sea-level rise exceeding marsh accretion rates.
 

This project addresses the following National Conservation Strategies:

  1. Protect intact and healthy waters.
  2. Restore hydrologic conditions for fish.
  3. Reconnect fragmented fish habitats.
  4. Restore water quality.

Southern FlowPhoto credit: Tillamook Estuaries Partnership

 

Southern Flow
Photo credit: Tillamook Estuaries Partnership

 

Southern Flow
Photo credit: Tillamook Estuaries Partnership

 

Southern Flow
Photo credit: Tillamook Estuaries Partnership