Download a free copy of the Adobe Acrobat Reader. This zoning is used to protect specific natural resources not explicitly safeguarded under existing regulations. Overlay zoning is particularly useful in establishing wellhead or source water protection areas in developed areas. Once the protection area is specified, overlays help share future changes in land use. The objective of performance zoning is to protect specific vulnerable or valuable natural resources.
Planners evaluate proposed developments' projected impact on the watershed.
Factors may include storm water runoff, wetland impacts, steep slopes, erodible soils, riparian areas, and ground and surface waters. In impact zoning, the developer minimizes harmful impacts. Developers are not told how to minimize these impacts, only that the final design must meet certain performance standards. These performance standards might establish, for example, that the sediment load in runoff cannot exceed pre-development loads. Communities today recognize they need to protect surface and groundwater supplies.