BIOLOGICAL RESOURCES


ERO provides creative and successful solutions to biological resource issues faced by our public and private sector clients.  As part of our client-focused approach to environmental compliance processes, we perform resource inventories and impact assessments, negotiate with regulators, develop mitigation plans, and monitor post-project conditions.  Our knowledge of natural resource systems and their associated regulatory processes results in science-based and defensible solutions that we deliver objectively and with integrity.


  • Wetland delineation and mitigation/Clean Water Act compliance
  • Biological assessment and habitat conservation plan
  • Endangered Species Act compliance; threatened and endangered species survey
  • Restoration, revegetation, and weed management
  • Biological investigation
  • Migratory Bird Treaty Act/Bald and Golden Eagle Protection Act compliance

Areas of Expertise

Wetland and Stream Services

Wetland delineations

ERO’s scientists are certified in wetland delineations and have extensive experience working in the Arid West, Great Plains, and Western Mountains, Valleys, and Coast.  ERO has delineated and mapped thousands of acres of wetlands ranging from eastern deciduous forested wetlands to high‐altitude fens in the Rocky Mountains.  We coordinate closely with state and federal regulators, especially the U.S. Army Corps of Engineers (Corps), to ensure that our delineations are accurate and meet all current regulatory guidelines.  ERO also assists with determining if potential waters of the U.S. are within a project area and works with the Corps to determine if these areas are jurisdictional or nonjurisdictional.

Functional Assessments

Wetland and stream functional assessments have become increasingly important and are useful tools in determining wetland and stream function and health.  ERO staff are trained in and apply a variety of functional assessment methods including:

  • Functional Assessment of Colorado Wetlands Method
  • Ecological Integrity Assessment for Colorado Wetlands
  • Hydrogeomorphic Wetland Classification System
  • Montana Wetland Assessment Method
  • Stream Quantification Tool
  • Functional Assessment of Colorado Streams Method

Clean Water Act Section 404 Permitting

ERO is a known regional expert in Clean Water Act Section 404 permitting and prepares applications for any 404 permitting that may be necessary for a project.  ERO staff work with project teams to understand the goals of the project and identify strategies that would reduce permitting requirements and streamline the permitting process.  ERO’s close working relationship with the Corps can help determine the most effective environmental approaches that are practicable, efficient, and acceptable to the Corps.

Ecological Restoration

Wetland Mitigation and Restoration

ERO has extensive experience designing and creating functional and diverse wetlands in the Great Plains, Western Mountains, and Arid West.  ERO’s wetland specialists have designed and monitored the construction of thousands of acres of wetland mitigation projects, from stream restoration projects to large wetland mitigation banks.  Working with engineers, landscape architects, and construction contractors, ERO has successfully overseen construction activities including grading, seeding, and planting native vegetation.  Our knowledge of the key components to a wetland, including hydrology, soils, and native vegetation, allows us to produce sustainable, functional, and diverse wetlands that can mitigate and enhance these ecological systems.

Revegetation and Restoration

ERO has considerable experience with revegetation projects that are designed to restore and enhance the ecological function of disturbed areas.  Our extensive understanding of diverse native plant communities has enabled us to successfully complete revegetation projects in lowland wetlands and riparian areas, native prairie landscapes, and high-altitude alpine environments.  ERO's restoration plans carefully consider the habitat, human use, and management needs of a project area, resulting in functional restoration solutions.  ERO uses our understanding of ecological principles, such as succession and plant/animal interactions, to design restoration, revegetation, and enhancement plans for native plant communities.  Our extensive experience with installation and monitoring ensures that our plans and specifications are clear and constructible and the design is successful and sustainable.

Noxious Weed Management

ERO has extensive knowledge of the noxious weeds in Colorado and effective methods for controlling these invasive species.  Throughout Colorado, ERO has surveyed for noxious weeds listed by the state per the Noxious Weed Act.  Based on the results of these surveys and knowledge of local environmental conditions, ERO has completed noxious weed plans that successfully eradicate or control noxious weeds while preventing deleterious impacts on nearby stream systems, native ecosystems, and agricultural lands.

Threatened and Endangered Species

Threatened and Endangered Species Surveys

ERO scientists are trained and certified to conduct surveys for a broad range of federal- and state-listed threatened and endangered species, Forest Service and Bureau of Land Management sensitive species, and management indicator species throughout the western U.S.  Our experience includes surveys for:

  • Preble’s meadow jumping mouse
  • Greater and Gunnison sage grouse
  • Southwestern willow flycatcher
  • Boreal toad
  • Black-tailed prairie dog
  • Burrowing owl
  • Black-footed ferret
  • Colorado hookless cactus
  • Ute ladies’-tresses orchid
  • Western yellow-billed cuckoo
  • Mexican spotted owl
  • Moonworts
  • Colorado butterfly plant

Endangered Species Act Compliance

ERO is recognized as an industry leader in Endangered Species Act (ESA) compliance.  ERO has completed habitat evaluations throughout the western U.S. for a variety of species and submitted hundreds of habitat assessments to the U.S. Fish and Wildlife Service (Service).  If projects may affect a federally listed species, ERO has expertise in preparing, implementing, and monitoring ESA permits.  This expertise includes all aspects of preparing ESA permits:

  • Agency consultation
  • Biological assessments
  • Habitat conservation plans
  • Candidate conservation agreements
  • Safe harbor agreements

ERO’s wildlife biologists and botanists can also help identify, design, and create habitat for a variety of species if required for mitigation or enhancement activities.  Our strong working relationships with the Service can help streamline ESA compliance and identify mitigation strategies that will be practicable, sustainable, and acceptable to the Service and project team.

Natural Resource Inventories

Biological Resource Studies

Through field surveys and research of existing information, ERO assists clients with pre‐disturbance inventories and natural resource assessments.  ERO has experience in the western U.S. with mapping, categorizing, assessing, and managing communities and habitats in a wide range of ecosystems.  We use the latest remote sensing and analysis technology including GIS, LIDAR, side-angle radar, and web-based real-time data analysis to identify and map vegetation communities or sensitive areas, prepare wetland functional assessments and riparian proper functioning conditions reports, conduct habitat equivalency analysis and rapid resource assessments, and develop project-specific models.  After determining which natural resources are present at a site, ERO can make recommendations to manage existing resources effectively and protect important wildlife or rare plant habitat while considering the needs of the client.

Wildlife Studies

ERO’s wildlife specialists perform surveys, assess habitats, develop management plans, and implement habitat mitigation/restoration plans for large and small mammals, birds, raptors, reptiles, and amphibians.  ERO conducts wildlife studies that focus on project‐specific issues, resulting in efficient and scientifically sound solutions that satisfy the requirements of wildlife agencies and meet client objectives.

ERO identifies wildlife or sensitive areas early in project planning and suggests strategies to avoid or minimize impacts or develop specifications and restrictions, which can prevent delays during construction.


Biological Resources Leads