Engineered Log Jams

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Engineered log jams are structures created in streams, rivers and floodplains designed to simulate the function of naturally occuring log jams. Due to logging practices, large 'key peices' of old growth trees with attached root wads are no longer common in rivers and streams. Log jams create forage and refuge opportunities for young and spawning salmon. While engineered log jams are temporary, they provdie habitat services, until riparian forests can grow the large trees to allow for natural formation of log jams.

  • Pess et al 2011 provides evidence of higher salmonid concentrations associated with log jams.
  • Maudlin & Coe 2011 provides observations of effects of ELJs on the South Fork Nooksack Floodplain
  • It appears that we only have conceptual evidence that the observed concentration of fish at ELJ sites in increasing population size and viability.
  • We have no specific examples where predictions about the effects of ELJ placement based on modelling or best professional judgement have been verified by monitoring floodplain structure over time.
  • A series of projects are being installed on the Lower North Fork Stillaguamish Floodplain
  • Leonetti et al 2015 describes long term monitoring of wood jams in the Stillaguamish, showing a general decline in jams, only partly offset by ELJ construction.
  • Collins & Montgomery 2002 proposes a strategic view of river wood restoration, including short term construction of ELJs.
  • Larson's Reach Floodplain Restoration was a two phase project by the Lummi Nation that constructed a set of jams to attempt bed aggredation in the South Fork Nooksack Floodplain.
  • Aldrich & DeVries 2015 describes a unusual wood installation effort that uses roughness to guide sedimentparticles of clay, silt, sand, gravel, or cobble, transported by water, are called sediment. routing and river migration.
  • Natural Systems Design has been exploring log jam placement which effects river geomorphology, and published a summary of their thinking in Abbe et al 2018