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<br /> <br />River and stream protection programs often establish bllffer zones IDitllin wl/icll tree:; or other vegetatiOll are to be left <br />undisturbed. Setbacks demark a point beyond U.1hich development CtUl/lOt encroacllllpon tile floodplain. Buffers and <br />setbacks are methods to minimize the impacts of adjacent development 011 the .floodplain alld all water quality. <br /> <br /> <br />common method is to base the required open space <br />acreage on projected population-generally ranging <br />from one to 10 acres per 1,000 residents (Listokin and <br />\Nalker 1989). Other communities use a percentage of <br />total subdivision acreage or the number of d\velling <br />units to determine open space requirements. <br />Modern ordinances differentiate behveen developed <br />and undeveloped open space, and specify the amount <br />of land that should be left in its natural state. Poulsbo, <br />vVashington, for example, encourages the retention of <br />natural areas by allowing up to 30 percent of the total <br />land donation area to consist of vvetlands, slopes, <br />floodplains, or other natural features, while the <br />remaining 70 percent of the dedicated land must be <br />suitable for recreational activities. <br />Drainage and floodplain regulations may provide <br />additional open space on a site or in a subdivision <br />beyond what is normally required. Drainage ordinances <br />that require detention and retention ponds and place a <br />limit on the amount of impervious surface on a site can <br />result in more open space overall in the development. <br />In floodplains, there are allmvances for transferring <br /> <br />Figure 3-5. Typical Riverine Buffers and Setbacks <br /> <br />f'-8UcFER 4- SETBACk~ <br /> <br />density and clustering units that provide an automatic <br />increase in open space. Fairfax County, Virginia, for <br />example, requires the open space in cluster <br />developments to have at least one acre of usable open <br />space outside the floodplain and have no dimension <br />that is less than 50 feet. As noted in the cluster <br />de\!elopment section, NFIP communities that also <br />participate in the CRS can help property owners reduce <br />flood insurance premiums by leaving land and open <br />space, and additional credit is given \vhere lands have <br />been left undisturbed or have been restored to protect <br />the natural and beneficial floodplain functions. <br /> <br />Greenways, Buffers, and Setbacks <br />Greemvays have emerged as a tool for linking <br />subdivision requirements with recreational and <br />floodplain management goals. A green way is a linear <br /> <br />open space established along a natural corridor, such as <br />a riverfront, stream valley, or ridgeline, or overland <br />along a railroad right-of-vvay, canal, scenic road, or <br />other route that has been converted to recreational use <br />(Little 1990). Some communities are requiring the <br />dedication of greem....ay easements along floodplains, <br />minor streams, and other linear features. The greenway <br />counts tmvard the open space requirement for a <br />subdivision. <br />The \Vinston-Salem/Forsyth County, North Carolina, <br />Vision 2005 plan recommends that all designated <br />floodplains in the county be set aside as green\vays. The <br />county subdivision ordinance requires a 40-foot <br />minimum greenway easement for all development <br />along floodplains. The state of North Carolina provides <br />tax credits for land donations for greenways and other <br />conservation purposes. <br />In the lexicon of zoning and land-use controls, buffer <br />areas are landscaped or ,vooded strips that separate <br />incompatible uses. Zoning and landscape ordinances <br />contain standards for buffers that are specific to each <br />use and to every district. Ordinance provisions typically <br /> <br /> <br />L-. BUtFER -+ ~ <br />~ SETBACK----", <br /> <br />r <br /> <br />ACCESS <br /> <br />dictate the buffer width and type of material to be <br />planted or the allowable height of fences or berms. <br />Setbacks are established in a zoning ordinance to <br />delineate the required distance between a building and <br />each lot line. Together, the front, side, and rear setbacks <br />make up the yards of the principal building on each lot. <br />The setback concept can be further applied in floodplain <br />or sensitive lands ordinances to separate urban develop- <br />ment from wetlands, coastal areas, riverbanks, or <br />floodplains. These setbacks, rather than just establishing <br />yards, are used to reduce the impact of development on <br />any of the environmental features that may be present <br />on a site. <br />River and stream protection programs frequently <br />establish some form of buffer zone and setback along <br />the banks of the \\raterway. The purpose is to ameliorate <br />the negative effects that adjacent development may <br /> <br />23 <br />