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Environmental Overlay Zones
Portland has established environmental overlay zones to protect and conserve significant natural resources. The environmental overlay zones are based on extensive natural resource inventories that cover areas within the City. The environmental zoning program is also the City’s primary tool for complying with State Land Use Planning Goal 5 to protect significant natural resources.
There are two types of environmental overlay zones, which currently affect approximately 19,000 acres. Protection zones have been established in areas that have very high value resources and functional vales. Development is approved in the protection zone only in very limited circumstances. Within the conservation zone, development is allowed if it meets certain standards and approval criteria to ensure that impacts on significant resources are avoided, limited, and mitigated.
The Bureau of Planning is in the process of updating Portland’s natural resource inventories and the environmental zoning program, with a focus on water bodies and wetlands, riparian areas, and wildlife habitat. This work is being coordinated with Metro’s effort to develop a regional program for protection of regionally significant natural resources (BOP, Title 33, Chapter 33.430).
Greenway Overlay Zones
The River General Zone allows for uses and development which are consistent with the base zoning, which allow for public use and enjoyment of the waterfront, and which enhance the river’s natural and scenic qualities. There are no special use restrictions in this zone. The greenway setback extends 25 feet landward from the top of bank. For development riverward of the greenway setback, applicants must comply with the following criteria: proposal will not result in the significant loss of biological productivity in the river, the riverbank will be protected from wave and wake damage, and the proposal will not restrict boat and beach access. For development within the greenway setback, applicants must show that the proposed development or fill will not have a significant detrimental environmental impact on Rank 1 and 2 wildlife habitat areas on the riverbank (identified in the Lower Willamette River Wildlife Habitat Inventory) (City of Portland Bureau of Planning, Title 3, Chapter 33.440).
The River Natural Zone protects, conserves and enhances land of scenic quality or of significant importance as wildlife habitat. There are no special use restrictions in this zone. The greenway setback extends 25 feet landward from the top of bank. For development riverward of the greenway setback, applicants must comply with the following criteria: proposal will not result in the significant loss of biological productivity in the river, the riverbank will be protected from wave and wake damage, and the proposal will not restrict boat and beach access. For development within the greenway setback, applicants must show that the proposed development or fill will not have a significant detrimental environmental impact on Rank 1 and 2 wildlife habitat areas on the riverbank (identified in the Lower Willamette River Wildlife Habitat Inventory). For development within the River Natural Zone, the applicant must show that the proposed development, excavation, or fill will not have significant detrimental environmental impacts on the wildlife, wildlife habitat, and scenic qualities of the lands in the River Natural Zone. The criteria apply to the construction and long-range impacts of the proposal and to any proposed mitigation measures. For development within 50 feet of the-zone, applicants must show that the proposed development will also not have a significant detrimental impact on the land in the River Natural Zone (City of Portland Bureau of Planning, Title 3, Chapter 33.440).
The River Water Quality Zone is designed to protect the functional values of water quality resources by limiting or mitigating the impact of development in the setback. The greenway setback extends 50 feet landward from the top of bank for sites with less than 25 % slope, or 200 feet landward for sites with 25 % or greater slope. For development riverward of the greenway setback, applicants must comply with the following criteria: proposal will not result in the significant loss of biological productivity in the river, the riverbank will be protected from wave and wake damage, and the proposal will not restrict boat and beach access. For development within the greenway setback, applicants must show that the proposed development or fill will not have a significant detrimental environmental impact on Rank 1 and 2 wildlife habitat areas on the riverbank (identified in the Lower Willamette River Wildlife Habitat Inventory). Additional approval criteria are also applied in the water quality setback (City of Portland Bureau of Planning, Title 3, Chapter 33.440).
The River Industrial Zone encourages and promotes the development of river-dependent and river-related industries which strengthen the economic viability of Portland as a marine shipping and industrial harbor, while preserving and enhancing the riparian habitat and providing public access where practical. The greenway setback extends 25 feet landward from the top of the bank. For development riverward of the greenway setback, applicants must comply with the following criteria: proposal will not result in the significant loss of biological productivity in the river, the riverbank will be protected from wave and wake damage, and the proposal will not restrict boat and beach access. For development within the greenway setback, applicants must show that the proposed development or fill will not have a significant detrimental environmental impact on Rank 1 and 2 wildlife habitat areas on the riverbank (identified in the Lower Willamette River Wildlife Habitat Inventory) (City of Portland Bureau of Planning, Title 3, Chapter 33.440).
The River Recreational zone encourages river-dependent and river-related recreational uses which provide a variety of types of public access to and along the river, and which enhance the river’s natural and scenic qualities. The greenway setback extends 25 feet landward from the top of bank. For development riverward of the greenway setback, applicants must comply with the following criteria: proposal will not result in the significant loss of biological productivity in the river, the riverbank will be protected from wave and wake damage, and the proposal will not restrict boat and beach access. For development within the greenway setback, applicants must show that the proposed development or fill will not have a significant detrimental environmental impact on Rank 1 and 2 wildlife habitat areas on the riverbank (identified in the Lower Willamette River Wildlife Habitat Inventory) (City of Portland Bureau of Planning, Title 3, Chapter 33.440).
Other Overlay Zones
The Scenic Resources Overlay Zone is intended to protect scenic resources identified in the Scenic Resources Protection Plan and enhance the appearance of Portland. This is achieved generally by establishing height limits within view corridors and by establishing additional landscaping and screening standards in scenic corridors. In scenic corridors, examples of standards include: two rows of trees, one deciduous and one evergreen, must be planted on 30-foot centers along the length of the building between the structure and the protected resources; no more than 25 % of the entire area of the street setback can be used for vehicle areas; and all trees over 6 inches in diameter that are within the street setback (or first 20 feet if no setback exists) must be retained unless removal conforms to additional standards (City of Portland Bureau of Planning, Title 33, Chapter 33.480).
The Design Overlay Zone promotes the conservation and enhancement of areas of the City with special scenic, architectural or cultural value. This is achieved through the creation of design districts and applying the Design Overlay Zone as part of community planning projects, development of design guidelines for each district, and by requiring design review or compliance with the Community Design Standards outlined in the Design Overlay Zone (City of Portland Bureau of Planning, Title 33, Chapter 33.420). More detailed design descriptions are provided for some subwatersheds.
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