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With a keen eye toward climate change and potential impacts on preserve ecology and infrastructure, ACR contracted with Laurel Collins of Watershed Services and Jason Pearson of Lotic Environmental Services to conduct a preliminary geomorphic assessment of the four watersheds in the Martin Griffin Preserve (MGP).  Project objectives included:

  • Provide a watershed level understanding of the current and long-term processes that affect flow, sediment sources, and sedimentation in the lower alluvial fans adjacent to the Bolinas Lagoon. 
  • Document October 2018 as-built conditions of Caltrans sediment removal and ditch clearing of drainage structures to Bolinas Lagoon. 
  • Determine the extent of streambed change over the 2019 rainy season.
  • Establish benchmarks and coordinates for future monitoring.
    • Develop an understanding of existing natural versus artificial processes and their influences on flooding and sedimentation at the canyon mouths, especially at SR 1 and developed infrastructure within the ACR property.
    • Determine the potential scouring and sedimentation influences of the April 2018 stormflow in Garden Club Canyon by resurveying the longitudinal and cross-sectional channel geometry at sites established in August 2016.
  • Develop an understanding of how future climate change and sea level rise will influence the conveyance of water and sediment from these canyons to the Bolinas Lagoon.

Copies of the complete report with appendices are available upon request.  (Contact Gwen Heistand, Martin Griffin Preserve Manager and Resident Biologist: gwen.heistand@egret.org.)