Leonetti 2015 stillaguamish temperature TMDL study

From Salish Sea Wiki





Leonetti, F. 2015. Stillaguamish temperature TMDL adaptive assessment and implementation project. prepared by Snohomish County Surface Water Management, Everett, Washington. 35 pp.

Notes

  • Evaluates the results of Puget Sound Characterization Project metrics describing water flow importance, and compares them to on-the-ground data describing stream temperature.
    • There was a weak correlation between lower water temperature and "recharge importance" and the "groundwater" component of the water flow importance model.
  • Snow fed creeks tend to be more sensitive to climate phase change than lowland rain fed streams.
  • 96 potential "cold water refuges" were identified and classed by source, intensity, and size.
    • Half of these were located in the northfork, where cold seeps, springs, and side channel inputs complemented tributary inputs. This is different from the South Fork which was dominated by tributary sources.
    • This suggests a different strategy in NF vs. SF, with NF focused on river and floodplain restoration, and SF focused on watershed management and confluence enhancement.
  • Continuous thermal profiling demonstrated areas of tributary and groundwater inflow that mitigated stream temperature in Jim Creek Watershed and Pilchuck Creek Watershed. Deep pool scour, may increase groundwater-streamflow interaction creating cold water refugia.
  • Groundwater seepage accounted for 60% of flow accumulation in the lower 7 miles of Pilchuck Creek. Increasing deep scour pools may enhance this potential influence on stream temperature. This points to the importance of capture and infiltration of water across the watershed.