Chapter 1.7
Urban Forestry and Vegetation

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

Cluster/Conservation Subdivision in Rural/Urban Area

INTRODUCTION

Clustered/Conservation Subdivision (CCS) ordinances allow residential developments in rural and urban fringe areas while retaining the natural character and significant wildlife habitat in the newly developed area. CCS developments are an alternative to traditional residential developments (often subdivisions and/or planned unit developments) that typically result in substantial destruction of natural features and habitat.[1] In contrast, CCS ordinances allow or require dense clusters of residential units in one part of the proposed project area, in exchange for permanently preserving open space and natural features.[2] Under this model, the open space is rendered undevelopable, but may be used by the community for recreation, agriculture, or conservation (for alternative ways to zone the PUD open space see Limit PUDs Near Sensitive Natural Areas). Placing CCS developments near the urban/rural boundary helps provide a natural transition from dense urban areas to more open and natural spaces.

Local governments may structure CCS ordinances in a variety of ways. Some local governments have chosen to create overlay districts that indicate where a CCS may be located.[3] Others may choose to allow a CCS directly in the regulations for various zones, most typically residential zones.[4] The ordinance should also describe the design standards for the CCS, such as maximum allowable surface coverage, minimum amount of open space required, and where or how the new residences will be clustered on the parcel. Local governments should note that CCS developments often require smaller minimum lot sizes than the underlying zoning district would otherwise allow to accommodate for tight clusters of buildings, so that more open space may be preserved. Many jurisdictions simply exempt CCS developments from minimum lot size requirements.[5] In many ordinances, there is a formula or ratio that indicates how much space developers must leave open. These formulas and ratios may be based on prior use patterns for new developments in communities that have traditionally had access to public open spaces, or they can be tailored to meet the needs of developments in communities that have historically been without open spaces. Finally, it is important for a municipality to specify what happens to the development rights of the preserved open space. Some local governments retain those development rights indefinitely, while others allow the transfer of those rights to non-profit land trust entities or a homeowners association.[6]

EFFECTS

Promoting CCS developments provides numerous benefits to local governments. First, preserving open space and wildlife habitat provides a natural corridor for wildlife to travel, and therefore increases the biodiversity in the jurisdiction.[7] One study found a strong correlation between using cluster type developments and the increased preservation of wildlife habitat and biodiversity, as compared to traditional residential developments, which had less wildlife habitat and biodiversity.[8] Second, the preservation of open space allows existing greenspace to continue to provide ecosystem services. Greenspace is open, undeveloped, or vegetated land that captures greenhouse gas (GHG) emissions and allows wildlife to move freely through a natural landscape.[9] The services that greenspace provide also include air purification, stormwater management and treatment, and soil retention.[10] Third, CCS developments help to ensure prime farmland is available to local farmers. Finally, one study found that homes in CCS developments gain monetary value at a quicker rate than traditional residential subdivisions.[11] Both homeowners and local governments may benefit from the resulting increase in assessed property value.

In contrast, a traditional residential subdivision consumes almost all of the greenspace on a parcel, which shifts costs to local governments to replace the loss of ecosystem services and potential farmland. Traditional residential subdivisions can also damage or destroy wildlife habitat and block existing wildlife corridors, thereby pushing wildlife out of the jurisdiction and harming overall biodiversity.[12] CCS ordinances mitigate these harms by allowing residential developments that complement the natural environment and preserve substantial wildlife corridors and habitat.[13]

EXAMPLES

Thurston County, WA

Thurston County is home to the state capitol of Olympia, which sits near the northern edge of the county border. Olympia has a large metropolitan area, but much of the County is rural and zoned as “Long Term Agriculture” (LTA) or “Long Term Forestry” (LTF).[14] Within these zones the County requires low density housing, which in some instances can mean one dwelling unit per eighty acres.[15] However, a landowner in a LTF or LTA district can apply to create a “Planned Rural Residential Development” (PRRD).[16] These PRRDs are exempt from minimum lot size requirements, allowing a developer to maximize profits while also retaining the rural character of the area.[17]

PRRDs require the creation of a “resource parcel.”[18] The composition of the resource parcel varies based on the underlying zoning district. For instance, in LTA districts the parcel must be used for agriculture, while in LTF districts the resource parcel must consist of forested land.[19] The percentage of the lot dedicated to the resource parcel also varies. In LTA districts, eighty-five percent of the PRRD must be a resource parcel.[20] In LTF districts, seventy five percent of the PRRD must be a resource parcel.[21] In all cases, the resource parcel must be one contiguous area of land, not intermingled with any residential developments.[22] This requirement insures that the residential development is limited to a small portion of the total platted area, thereby preserving natural wildlife corridors and habitat.

The County further regulates how residences are situated in the PRRD. Homes must blend in with the natural features as seen from the public roadway, and the configuration and size of lots must vary.[23] Lots must be grouped, rather than arranged in a linear fashion.[24] The goal of these requirements is to provide unhindered access and use of the resource parcel, and promote a pleasant rural aesthetic as viewed from the highway.[25]

To view the provisions, see Thurston Cty., WA, Code of Ordinances § 20.30A (1993).

Jamestown, RI

Jamestown is located on an island just West of Newport, Rhode Island. A majority of the jurisdiction is zoned for low-density residential uses.[26] Within three of the largest of those zones, clustered development is required for any subdivision of land over five acres (emphasis added).[27] The planning commission will only approve a traditional type residential development if it determines that a clustered development is inappropriate due to “land configuration, prevailing development adjacent to the parcel, or environmental condition.”[28]

In a cluster development, the town requires that fifty percent of the area be devoted to open space[29] (see Limit PUDs Near Sensitive Natural Areas). Permitted uses in the open space are limited to conservation, recreation, agriculture, and preservation of historic sites.[30] However, a developer may construct certain structures in the open space, such as walkways, retaining walls, recreational facilities, or utilities.[31]  Notably, any open space that has been deemed “unsuitable for development” will not count towards the fifty percent requirement.[32] The open space must then be conveyed to the Town, to a cooperative or homeowners association, or donated to a non-profit land trust entity.[33]

The Town also sets minimum lot sizes for clusters based on the underlying zoning district. For example, in the zone designated as rural-residential that normally requires minimum lot sizes of 200,000 square feet, that requirement is reduced to 20,000 square feet.[34] On the other end of the spectrum, the zone that normally requires at least 40,000 square feet lots only requires 8,000 square feet lots in cluster developments.[35]

To view the provisions, see Jamestown, RI, Code of Ordinances § 82-1600 to 1608 (2003).

Baltimore County, MD

Baltimore County is a largely rural jurisdiction with the City of Baltimore on its Southern border. The County’s zoning regulations establish several zones designed to preserve rural resources and the natural character of the county.[36] CCS developments are required in some cases for the subdivision of land in certain “Resource Conservation” districts. [37]

For example, in the Watershed Protection zone, any development of a parcel of land greater than ten acres must be a clustered design.[38] 70% of the tract must be reserved as the “conservancy area.”[39] Whenever possible, the conservancy are must be a contiguous block of land that contains valuable ecological features such as prime soil, steep slopes, wetlands, and forests.[40] The conservancy area is required to be held by a single entity, such as a land trust or homeowner’s association, and a permanent preservation easement must be placed over the area.[41] The entity that owns the area must also file an agreement with the county to take responsibility for maintaining the area and preserving it as is.[42]

To view the provisions, see Baltimore Cty., MD, Zoning Regulations § 1A03.5 (1992).

ADDITIONAL EXAMPLES

Loudon Cty., VA, Code of Ordinances § 1226.02 (a) (1998) (exempting clustered developments from a ten-acre minimum lot size per dwelling requirement in agricultural and forest districts).

Concord, MA, Zoning Bylaw § 9.1-9.5 (1962) (allowing cluster developments reduced minimum lot sizes and requiring fifty percent of land be perpetually maintained as open space for agriculture, parks, recreation, or conservation).

Chiply, FL, Code of Ordinances § 20-135 (1992) (requiring that cluster developments preserve fifty percent open space in exchange for reducing the minimum lot size from one dwelling unit per ten acres, to two dwelling units per acre).

Amherst, MA, Zoning Bylaw § 4.34 (2014) (providing a detailed ratio for “developed land” to “common land” in Amherst’s Cluster Developments. For every dwelling unit, the code requires 2,000 square feet of usable common land).

ADDITIONAL RESOURCES

Guidelines for Calculation and Provision of Open Space in Developments of Regional Impact Technical Bulletin 94-001, as Amended, Cape Cod Commission 5-7 (May 4, 2009).

Public Dedication of Land and Fees-in-Lieu for Parks and Recreation: A Tool for Meeting Recreational Demands in Pennsylvania Municipalities, Pennsylvania Land Trust Association (2015).