Water budgets of individual local trees

Washington Department of Natural Resources (DNR) is collaborating with Washington State University, City of Tacoma, The Evergreen State College, and Clemson University on a project to measure the effectiveness of local mature forest trees (Phase I study) and younger, smaller trees (Phase II study) to mitigate stormwater runoff in Western Washington. 

Study objectives

This study is desgned to answer how much rainfall is managed by an individual tree. It will:

  • Quantify annual transpiration rates and annual canopy interception rates for evergreen and deciduous trees native to the Pacific Northwest.
  • Complete water budget and estimate hydrologic value of existing trees. 

The Phase I study quantified hydrological benefits of mature trees, and the Phase II study will collect data on younger and smaller trees, like those common in more urban areas. 

Project tasks and key contract deliverables

Phase I (mature forest trees)

Contract and scope of work

  1. Project administration
  2. Quality assurance project plan development
  3. Instrument purchase and installation
  4. Instrument maintenance and data downloads
  5. Data analysis and QAQC
    • Copy of data: contact SAM staff 
  6. Final report on mature trees and stormwater mitigation
  7. Communication & outreach

Phase II (younger, smaller trees)

Contract and scope of work, Amendment 1

  1. Project Administration 
  2. QAPP amendment 
  3. Instrument installation and monitoring 
  4. Instrument maintenance and downloads - see biannual reports above
  5. Data analysis and submittal 
    • Copy of data 
  6. Final Phase II report 
  7. Communication and outreach
    • Presentation
    • Fact sheet