Skip sidebar navigation

Environmental Overlay Code and Map Update

  • The City is updating code in environmental areas that include streams, wetlands, floodplains and hillsides. Environmental areas or “overlays” protect natural areas during development. Updating the code language will make development requirements easier to follow. This protects property, public health and safety.

    See if your home is in an environmental overlay.

    Project goals

    • Update City code to comply with state and federal regulations. 
    • Improve development guidelines to help protect natural areas. 
    • Simplify mapping to clearly identify environmental zones or overlay areas. 
    • Streamline the review and permitting process.
    • Project Status and Updates
    • Homeowner Information
    • Project Background
    • Contact
    Project Status and Updates
    Homeowner Information

    Look up your property on the overlay map.

    There are two types of overlays that may impact your property.

    Hillside and Geologic Risk Overlay

    View map of this overlay.

    There are no new property restrictions:

    • Altering or replacing structures but not changing the building footprint.
    • Moving less than 10 cubic yards of earth outside of the Highly Sloped Area.
    • Building a retaining wall under 4 feet in height outside the Highly Sloped Area.

    Some changes may need a geotechnical engineer to approve the design and may require a land use permit.

    Natural Resource Overlay

    View map of this overlay.

    Changes to the Natural Resource area allow for the protection of streams, wetlands, and valuable habitat.

    There are no new property restrictions:

    • If you have a 5000 ft. lot and are far enough away from a stream or wetland.
    • If your property is separated from the resource by the road there will be no special restrictions at all. 

    Some changes may need a land use permit if you have a very large lot or have a stream or wetland on your lot.

    Most properties in the Natural Resource Overlay (NRO) are currently in a Habitat Conservation Area (HCA) or Environmentally Sensitive Resource/Restoration Area (ESRA). The NRO boundaries may be different because the stream and wetland buffers are now more specific and predictable.

    Trees and vegetation

    Inside the overlay, most trees not part of a landscaped area will need to be preserved. The City will issue permits for the removal of hazardous trees.

    The City encourages invasive species removal. City staff are available to help you better understand how to protect and improve natural areas. Learn how to spot wildlife inside protected habitat. Contact Environmental Services for assistance at 503-618-2525.

    Project Background

    What are environmental overlays?

    Environmental overlays are extra levels of protection in certain areas of the city to protect natural resources such as streams, wetlands and hillsides.  

    Gresham has three environmental overlays:
    • Floodplain Overlay District (Revised in 2019 based on new Federal Emergency Management Agency (FEMA) data.
    • Hillside Physical Constraint Overlay District that protects steep slopes and hillsides.
    • Habitat Conservation Area Overlay District that protects streams and wetlands in most of Gresham.
    Gresham has two Environmental Zones
    • Environmentally Sensitive Restoration Area in Pleasant Valley.
    • Environmentally Sensitive Resource Area in Springwater.

    Together the system provides a network of green areas, wildlife habitat, streams and forested slope protections. 

    Proposed changes  

    • Simplified mapping, using the latest data available.
    • Clear standards within the resource areas.
    • Introduction of a temporary disturbance area. 
    • More flexibility in mitigation design.
    • Hillside boundaries aligned more tightly with newest risk data.

    Natural resource protections

    • Greater protection closer to streams.
    • Introduction of an in-lieu fund to allow for off-site mitigation.
    • Robust density transfer to incentivize avoiding resource areas.
    • Reduction of permanent disturbance areas.
    • Easily enforceable boundaries.
    • Promotion of biodiversity in mitigation efforts (more climate resiliency).
    • Increased geotechnical review of development in highest risk areas. 

    Completed public meetings


    For additional information concerning the proposed changes (Council Bill No. 12-20) contact Sarale Hickson, Project Planner, at or 503-618-2804.

    Due to the restrictions in place established by the Governors Stay-at-Home order, the hearings will be held via Zoom.

    Persons who desire to provide comments and are unable to provide written comments in advance or are otherwise unable to access the meeting via Zoom are encouraged to contact Jennifer McGinnis at or 503-618-2221 at least 24 hours in advance of the meeting so that the City can provide alternate arrangements.

    • Environmental Overlay Aerial
    • Heron

    1 of 3
    • Environmental Overlays balance development and other activities with environmental protection and public safety. 

    • Overlay areas buffer streams and wetlands from development, protecting natural areas.