what we do

Biological Sciences & ESA

Delivering pragmatic, science-based strategies to benefit our environment

Our team of biologists, ecologists, and environmental planners blend practical experience with scientific understanding to develop solutions that work. Our approach includes developing a range of strategies to manage risks, building on best practices, and streamlining the permitting and mitigation process. We help our clients comply with the Endangered Species Act (ESA) and achieve policy goals and directives, reduce regulatory compliance delays, reduce risk, improve stakeholder relationships, and improve the health and resiliency of our environment.

SR 520 Bridge Replacement and HOV Program Biological Consulting
SR 520 Bridge Replacement and HOV Program Biological Consulting
King County, Washington
Client: WSDOT
Partner: HDR Engineering

This 7-mile transportation corridor improvement project involves replacing a floating bridge over Lake Washington and 17 stream crossings. ESA consultation was initiated early with the goal of conducting biological assessments that thoroughly addressed all requirements of the ESA and provided NMFS and USFWS with the information needed to develop biological opinions that contain no surprises. Wetlands were classified and rated according to their relative rarity, sensitivity to disturbance, and quality of functions.

This information was used during project permitting to establish replacement ratios for compensatory mitigation. A comprehensive fish passage and culvert design analysis was completed, including analyzing various stream realignments and recommending upgrades or replacement for structures that acted as a barrier to fish passage.



  • Inland Avian Predation | Parametrix

    Inland Avian Predation Management Plan

  • Hualapai Range Survey | Parametrix

    Hualapai Range Survey

  • East Lake Sammamish Trail | Parametrix

    East Lake Sammamish Trail

  • Columbia River Crossing | Parametrix

    I-5 Columbia River Crossing Fish Hydroacoustics Study

  • Rio Grande Bosque | Parametrix

    Rio Grande Bosque Rehabilitation

  • SR 520 Bridge | Parametrix

    SR 520 Bridge Replacement and HOV Program Biological Consulting


"Parametrix has field staff that is very knowledgeable in plant identification, soils, and ecology. They are excellent to work with and very willing to share their knowledge and experience in data collection."

Robin Honani, Manager, Hualapai Agriculture Program