Chapter 2.1
Floodplain and River Corridor Land Use

• ALL
• Remove Code Barriers
• Create Incentives
• Fill Regulatory Gaps

Large-Lot and Preservation Zoning in Rural Areas

INTRODUCTION

Large-lot zoning allows local governments to mitigate the harmful effects of residential developments in previously undeveloped areas. These ordinances limit sprawling residential development that would otherwise destroy or fragment existing wildlife habitat, preservation, and agricultural lands in rural areas. These regulations typically require new residential developments in rural areas to have lot sizes large enough to preserve existing vegetation, open space, and natural features for native wildlife.[1] By requiring large lot sizes, a local government insures that new residential developments are more easily “integrated into the existing ecosystem,” providing suitable space for wildlife habitats.[2]

Local governments can implement these ordinances in a variety of ways. The simplest method is to prescribe large minimum lot sizes directly in rural or agricultural zoning districts.[3] A local government could also attach landscape preservation requirements to large minimum lot sizes. Further, developers could be required to comply with site design regulations, such as wildlife friendly fencing regulations or regulations requiring building placement away from sensitive areas.[4] Finally, the most complex structure is to establish a conservation overlay district that covers existing rural/agricultural zones and requires any new residential developments to have large minimum lot sizes.[5] These overlay zoning ordinances add standards to the density requirements and permitted uses found in the underlying zoning district so that the community does not rezone entire districts.[6]

Some of these ordinances that have already been enacted allow the undeveloped portion of large lots to be used for agricultural or other purposes. The most effective way to preserve wildlife habitat with these is to establish conservation standards in conjunction with large lot zoning regulations.[7] The conservation areas should identify undeveloped areas that are either environmentally sensitive to development or contain critical wildlife habitat areas.[8] The local government can then expressly prohibit development in these areas, or allow development only upon the grant of a permit.[9] When reviewing such permit applications, the local government may also consider the impact any development would have on ecosystems, the availability of alternative sites for such development, and how the development fits in with the general land use plan for the area.[10] Local governments may also set aside a percentage of the undeveloped lot for conservation or other uses.

EFFECTS

Establishing these regulations allows a local government to require a large lot size for single-family developments in rural areas thus limiting the adverse impacts of quasi-dense sprawl, preserving valuable agricultural assets, and ensuring ample habitat space for wildlife. Moreover, there will be more open, vegetated land that can capture greenhouse gas (GHG) emissions and allow wildlife to move freely through a natural landscape.[11] Providing such corridors for wildlife to move promotes biodiversity in the area.[12] Open space also provides several valuable “ecosystem services,” such as air purification, carbon capture, storm water management, soil retention, and recreation.[13]

Conversely, ordinances that allow residences in rural areas to be constructed on smaller lots, such as lots less than 20 acres, eat up open space and thereby fragment or destroy valuable habitat and agricultural land. This results in interference with wildlife migration, displacement of wildlife, and the conversion of rural or agricultural land into sprawling residential subdivisions. Further, the cost of replacing the lost ecosystem services may shift to the local government by way of increased storm water runoff costs, increased healthcare costs due to reduced air quality, and a less productive agricultural industry due to increased soil erosion.[14] Requiring large lot sizes and establishing conservation zones therefore protects municipalities, wildlife, and greenspace from the threat of inefficient, unnecessary, and/or premature urban expansion.

EXAMPLES

Crook County, OR

Oregon is unique in that state law sets forth the minimum lot size allowed in districts zoned for “exclusive farm use” (EFU) and “rangeland.”[15] In general, land in EFU zones may be used to grow crops, raise livestock, keep bees, and for other associated agricultural activities.[16] Rangeland is rural land within EFU zones that is unsuitable for cultivation, but can be used for grazing animals.[17] For EFU zones, minimum lot sizes are set at 80 acres.[18] For land designated as rangeland in EFU zones, the minimum lot size is 160 acres.[19]

Crook County implements this state law in its zoning code, but takes it a step further. The County has designated areas that are critical to wildlife habitat within EFU zones.[20] In these areas any proposed division of land is subject to heightened minimum lot size requirements. For example, 323,200 acres (about 500 square miles) of land in the County has been designated as “elk wintering range,” in which the minimum lot size is set at 320 acres.[21] Similarly, in the 215,200 acres of “deer wintering range” the minimum lot size is 160 acres.[22] The County’s goal with these ordinances is to preserve sufficient habitat and vegetation for the animals to survive the winter. Thus far, that goal has been achieved. Deer populations in the state have held relatively steady while Elk populations have increased, thanks in part to these ordinances.[23]

To view the provisions, see Crook County, OR, County Code §§ 18.16-18.24 (2003).

Clark County, WA

Clark County is located on the border between Washington state and Oregon, just north of Portland, Oregon. The County contains a large metropolitan center surrounded by a heavily forested rural area. Recognizing the substantial benefits that the rural land provides, the County has established zoning districts designed to protect wildlife and biodiversity in the jurisdiction.[24] Land within rural areas is zoned based the amount of forest present, as well as the presence of significant wildlife populations.[25] For example, in the “Forest 80 District”, a district that indicates the presence of highly important forest resources, the minimum lot size is 80 acres per residential dwelling unit.[26]

Land that contains significant agricultural resources and also serves as an important wildlife habitat is zoned as “Agriculture-Wildlife” (“AG-WL”).[27] In AG-WL zones, the minimum lot size is set at 160 acres.[28] In both of these districts, developers are required to design the site so that it minimizes the impact on wildlife corridors and habitat. For example, developers are often required to “cluster” building near each other, rather than spread them out over the entire parcel.[29]  By combining large lot sizes with wildlife friendly site design requirements, Clark County has ensured that both rural resources and wildlife habitat are preserved.

To view the provisions, see Clark Cty., WA, County Code § 40.210.010 (2005).

ADDITIONAL EXAMPLES

Skagit Cty., WA, County Code § 14.16.400 (1979) (establishing “agricultural- natural resource” zones with minimum 40 acre lots and allowing only agricultural uses).

Sacramento Cty., CA, Zoning Code § 2.4.2 (2015) (requiring minimum lot sizes of up to 160 acres in certain districts to discourage the premature conversion of rural land into urban land).

Blaine Cty., ID, County Code §§ 9-4-2, 9-20-7 (1977) (setting minimum lot size in certain rural districts at 40 acres, and establishing overlay zones that require site design that is sensitive to wildlife habitat).