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It
is recommended that developing municipalities incorporate open space/conservation
developments into their master plan if it has not already been done. 
These
types of development promote a reduction in street width, smaller lot
sizes, and the elimination of sidewalks, curb and gutter.
Communities may encourage this type of development through bonus lots
and development of ordinances suitable to open space development to expedite
the approval process.
The Center for Watershed Protection has developed a Codes and Ordinances Worksheet (COW) to help communities evaluate their current development rules. This tool is best used by a local-site planning roundtable made up of representatives from government, developers, and environmental groups. The COW consists of 66 questions that correspond to the principles of better site design and points are awarded if the local development rule agrees with the COW principle.
Open-space
design involves concentrating development in a compact area of the site,
leaving the remainder of the site as open space or natural areas. This
type of design is also referred to as cluster or conservation development.
Open-space design integrates stormwater management into the core of the
site design. (1)
The benefits to stormwater management provided by
this type of development over conventional subdivision design include:
--- Impervious cover is minimized, reducing runoff and pollutants
--- Existing vegetation that absorbs and minimizes runoff is maintained.
Pollutants contained in the runoff are also absorbed.
--- Turf areas are minimized, reducing the area where nutrient-rich fertilizer
and pesticides are applied.
--- Overall land disturbing activities are minimized, resulting in less
construction site erosion if proper management techniques are used.
--- Existing natural areas are preserved.
--- Efficient use of infrastructure.
The Center for Watershed protection reported that nutrient export declined by 45 to 60 percent when two conventional subdivisions were redesigned as open-space developments. They also noted that impervious cover was decreased by an average of 34 percent over conventional subdivision design. (2) It has also been shown that as much as a 50-percent reduction in impervious surface over conventional design can be achieved depending on lot size and road network. (3)
Open-space developments contain some design features that usually require departure from typical zoning ordinances. It is important to note that many communities do not have ordinances in place to allow this type of development. Lack of proper ordinances can significantly slow the development process.
The following are design features that would promote conservation development:
--- Street widths may be reduced and would not normally allow for on-street
parking.
--- Sidewalks may be eliminated or provided on only one side of the road.
Natural walking paths are instead provided throughout the development.
--- Roadside swales are typically used for drainage rather than curb and
gutter.
--- Lot sizes are typically smaller and only a portion of the lot may
be cleared for construction. This allows for backyard common space, minimizes
turf area and maintains existing vegetative buffers.
--- Bonus lots are offered to developers as an economic and environmental
benefit for preservation of natural open space. Developers may be allowed
an increase in the number of lots beyond the density permitted in the
underlying zoning as an incentive to preserving existing open space.
--- Some conservation developments may also require relaxation of typical
setbacks from streets and adjacent structures to minimize disruption to
natural areas.
Rain
Gardens (Bio-retention)
Use of rain gardens to mitigate stormwater runoff may be incorporated
into open space design requirements. For more information on rain
gardens follow the link here. (4)
Open-Space Regulations
The state does not require open space development.
However, use of the open space design can provide credit towards meeting
the infiltration performance standard of NR 151.12(5)(C).
Source for text in oval:
City of Mequon Development Ordinance. Chapter 3 Zoning and Subdivision
Regulations (3.08(2))