Contact this Expert Witness

  • Company: Peninsula Environmental
  • Phone: (360) 819-3081
  • Cell: 360-504-3825
  • Website:

Specialties & Experience of this Expert Witness

General Specialties:

Arborist and Environmental

Keywords/Search Terms:

arborist, tree risk, tree appraisal , tree valuation, environmental restoration, habitat restoration, tree forensics

Years in Practice:


Number of Times Deposed/Testified in Last 4 Yrs:


Additional Information

John Bornsworth is the owner and Principal of Peninsula Environmental Group, Inc., with 20 years of tree-related and natural resources experience. John specializes in urban & community forestry planning and policy; tree forensics, pathology, risk management, and providing expert witness testimony.  As of January 2021, there are 14 ASCA Registered Consulting Arborists (RCA) and 30 ISA Board Certified Master Arborists (BCMA) in Washington out of 417 ISA Certified Arborists. Only 7 individuals hold both the RCA and BCMA credentials together. Roughly 300 professionals hold both credentials nationwide, as of January 2021.  Attended and passed first Tree & Plant Appraisal Qualification training by ASCA. Less than 200 hold this credential nationwide, as of December 2023.  Routinely provide expert opinion and testimony on arboricultural, horticulture and vegetation management to areas of legal practice that include land use, real estate, trespass, negligence, and personal injury. Retained as expert witness on over 60 projects and have provided sworn testimony approximately 25 times.  Experienced as expert witness for both Plaintiff and Defendant.  Won 2023 Planning Association of Washington Sustainability Award for City of Tumwater Urban Forest Assessment and Management Plan.  Have consulted, reviewed, or revised 14 urban forestry plans, natural resource plans, and tree related public policy and codes for jurisdictions across WA state.  Developed urban forest benchmarking tools to be used in urban forest planning. Benchmarked Washington State urban forestry planning and practices to assist in urban forest planning and development.  Provided critical area policy and environmental policy navigation to thousands of clients in western Washington since 2015, including policies related to trees, wetlands, shoreline and other protected environmental assets.  Represent commercial arboriculture on Washington Urban & Community Forestry Council, since 2017. Vice-chair of council 2020-2022.