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Wetland restoration after a mega-storm

Wetland restoration after a mega-storm. Jyneen Thatcher, Wetland Scientist Washington Conservation District Paul Bockenstedt, Ecologist Stantec. Prior conditions. South Twin Lake- an impaired waters. Wetland delineation. Brown’s Creek – a designated trout stream. Approved development.

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Wetland restoration after a mega-storm

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  1. Wetland restoration after a mega-storm Jyneen Thatcher, Wetland ScientistWashington Conservation District Paul Bockenstedt, Ecologist Stantec

  2. Prior conditions South Twin Lake- an impaired waters Wetland delineation Brown’s Creek – a designated trout stream

  3. Approved development

  4. Site conditions

  5. Rainfall

  6. August 14, 2007 Sediment and mulch against silt fence

  7. August 14, 2007 Brown’s Creek Sediment plume

  8. Site observations

  9. Pond Slope Old excavation (1980s) Floodplain Old blow-out to Creek (1990s) Brown’s Creek Sediment flow ------

  10. My observations

  11. Problem list - wetlands • Sediment fill into seepage wetlands and upland buffer • Sediment into floodplain wetland and excavation • Old blow-out into stream • Hierarchy of impacts across the site • Design of restoration order Buried bottle gentian in seepage area

  12. Planning the restoration • Timing of restoration • What/how to restore • Impact on private land • Coordination with other agencies (DNR, BCWD, PCA) • Responsive developer

  13. First steps • Stabilize site against more damage • Stabilize outlet to Creek • Develop restoration plan • Hire ecologist

  14. Next steps • Better stabilization of pond outlet • Discuss options with ecologists

  15. Restoration plan development • Summarized conditions • Identified areas for restoration • Areas with sediment • Surrounding invasive, nonnative areas • Outlet design for previously drained wetland • Identify locations for monitoring • Outline implementation specific to each sedimentation area

  16. Restoration implementation • Initial Restoration • Supplemental native seeding with diverse, local ecotype seed mix • 45 spp. forbs, 5 spp. graminoids • Cut/treat invasive, nonnative vegetation

  17. Restoration implementation • Initial Restoration of Stone wetland • Reconstruct outlet of previously drained wetland • Sediment removal • Native seeding of disturbed areas with BWSR mix • Grow-in maintenance • Spot spray, spot mow, hand weed

  18. Monitoring • Initial data collection at monitoring points in fall 2007 • Annual monitoring 2008-2011 • Data collected at five locations • Within sedimentation areas • In wetland with reconstructed outlet

  19. Monitoring • Results after 4 years • Buried seepage wetlands exhibit overall diminished quality • Loss of some desirable natives in areas with ~4-6+ inches of sediment (i.e. bottle gentian) • Some desirable native species stable, post-sedimentation • Rebound of nonnatives and invasive natives in some areas Bottle gentian and foxglove beardtongue in buried seepage area

  20. Monitoring • Results after 4 years • Overall reduction of invasive, nonnative cover • Good establishment of seeded native grasses and forbs • 20+ spp. established • 35-45% cover (A1 - C1) • Vegetation management along Brown’s Creek contributes to long-term improvement Area cleared of dense buckthorn/honeysuckle and seeded to natives (top 2009, bottom 2010)

  21. Site A-1 September 2008

  22. Site B-1 September 2008

  23. Site A-1July 2010

  24. Site B-1 July 2010

  25. Monitoring • Results after 4 years • Restoration of pond is success, with good diversity of vegetation and stabilized outlet

  26. What went right • Spirit of cooperation, trust and mutual respect among agency and private sector staff involved • Reasonable proposals for timing • Cooperative developer/landowner • Agreement with private landowner • Support by other agencies for this process

  27. Wetland restoration after a mega-storm • Thank you! Questions? Jyneen Thatcher, Wetland ScientistWashington Conservation Districtjyneen.thatcher@mnwcd.org 651.275.1136 ext.37 Paul Bockenstedt, Ecologistpaul.bockenstedt@stantec.com651.604.4812

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