Contributors: J.A. Arnold, S.W. Coffey, D.E. Line, and J. Spooner, Extension Biological & Agricultural Engineering Specialists, and D.W. Moody, U.S. Geological Survey

STORMWATER MANAGEMENT PRACTICES

Land Use Management Practices

Land use management usually implies controlling or restricting the uses of land in the watershed to reduce pollution. It can also include the use of site planning, which means designing the placement of buildings, homes and roads to minimize pollution impacts. Good land management practices can result in significant improvements in water quality yet require little or no maintenance and are very low in cost.

Low-density development. Limiting the density of development and the amount of impervious area greatly reduces the impact of storm-water on streams, rivers, lakes and oceans. Lower percentages of built-upon land of the total land available mean smaller stormwater volumes and less pollutant loading. Developers should consider low-density options for their developments, not only from the aspect of improved water quality, but also because construction of stormwater control measures may not be needed. If no stormwater control structures are needed, the developer saves construction and maintenance costs on the structures, and avoids the risks of potential failure of the structures. Developments with lower densities may result in higher selling prices per lot due to the increased space around each dwelling or building.

Comprehensive site planning. Fitting the development to the site to minimize land disturbance greatly reduces erosion and sediment in nearby water bodies, not only during construction but throughout the life of the project.

The "fingerprinting" technique identifies the ultimate development desired and fits in all necessary components during the planning stage. Fingerprinting minimizes reworking the site and makes provision for all needs early in the site development.

Cluster development is a technique in which all built-upon areas are placed together rather than spread out over the entire site. Using clustering, developers can place the desired residential or commercial space as far as possible from the receiving water and minimize impervious surfaces such as access roads.

Table 4. Low-Density Development Standards in North Carolina (as of January 1, 1993, C15A NCAC 2H.1000 and 2B.0200 for specific legal requirements). 1,2
Location Built upon Area Lot Size
All Counties

In watersheds with waters classified WS-I through WS-IV

Check local government regulations.

Coastal Counties*
Within ½ mile and draining to saltwaters classified as SA 25 percent 1/3 acre
Within 575 feet of saltwaters classified as Outstanding Resource Waters (ORWS) 3 25 percent 1/3 acre
All other waters in coastal counties 30 percent 1/3 acre
Other Counties

Within 1 mile of and draining to waters classified as High Quality Waters (HQW 3 )

12 percent

1 acre

Near waters classified as Outstanding Resource Waters (ORW)-Freshwater' 12 percent 1 acre

  • Includes: Beaufort, Bertie, Brunswick, Camden, Carteret, Chowan, Craven, Currituck, Dare, Gates, Hertford, Hyde, New Hanover, Onslow, Pamlico. Pasquotank, Pender, Perquimans, Tyrell, and Washington.

    • 1 Alternative or innovative structural stormwater controls may be allowed, on a case-by-case basis.

    2 Vegetative buffers, of minimum 30 foot width and adjacent to the surface water, are required for all developments. Buffer width is measured horizontally from the normal pool elevation of impounded structures, from the bank to each side of streams and rivers, and from the mean high water line of tidal waters, perpendicular to the shoreline.

    3 The Environmental Management Commission may require more stringent controls on a specific site to protect the values and maintain existing and anticipated uses of these waters.

    Phased development can be used to avoid disturbing large areas that will not be needed for long periods of time. Seasonal development avoids construction activities during weather that could cause undue pollutant loading in runoff or adversely affect sensitive plant or animal species.

    Minimum requirements can be established for tree coverage and non-built-upon land. Limits must be set for the amount of land permitted to be disturbed and for slope steepness. Minimum slope protection requirements should be defined.

    Plan and design industrial sites to put as much undisturbed or vegetated area as possible between buildings and water. Use clustering and fingerprinting to locate buildings and large impervious areas. Shorten access roads and avoid direct, high-velocity discharges of stormwater into streams. Design grassed swales for roadside drainage and route storm-water onto vegetated areas to encourage infiltration and sediment removal. Install porous pavement, precast cellular concrete paving (turf blocks), flexible revetment, or gravel for roads, truck aprons and parking lots.

    Locate municipal buildings and maintenance centers away from the receiving waters. Minimize bare areas around street and vehicle service garages. Require new developments in the city limits or new annexations to be designed to reduce the impacts of stormwater.

    Minimize stormwater impacts by locating homes and other built-upon areas away from receiving waters. Shorten driveways and subdivision roads as much as possible and locate the roads so they do not follow streams. Use grassed swales for roadside drainage and route stormwater to vegetated areas to maximize infiltration and sediment removal. Encourage the use of porous pavement, precast cellular concrete paving (turf blocks), flexible revetment and gravel for driveways and parking areas.

    Land use planning and zoning. Municipalities, counties and other governing bodies can establish plans or zoning regulations which allow sensible development while protecting the natural resources of the area. The community may decide or other regulations may determine the level of protection needed to ensure the desired level of long-term environmental quality. Planning and zoning rules are created by boards or commissions responsible for planning, zoning, public health, or ground water and wetlands protection.

    Planning and zoning rules may restrict certain activities in areas near water bodies or set aside strategic areas to prevent pollution problems.

    Resource-based master planning is the preferred method to protect resources and allow development of the area. Watershed protection plans and cluster development are some of the methods used to promote environmental protection.

    By guiding certain land uses to areas where the environmental impacts are minimized, citizens can enjoy the benefits of industry, development and a protected environment. Planning bodies can devise long-range plans to give industry, developers and private citizens the opportunity to be involved and comply with development plans which can enhance the community for all.

    Buffer zones. Buffer zones are strips of undisturbed natural vegetation or planted vegetation around water bodies. Such vegetated zones help reduce the impact of runoff by trapping sediment and sediment-bound pollutants, encouraging infiltration, and by slowing and spreading stormwater flows over a wide area. Many local and state programs incorporate buffer zone regulations to protect rivers and lakes that are drinking water supplies, private and public wells and wetland areas. Information on buffer zones can be found at local Soil Conservation Service offices and other government agencies.

    Buffer zones should be wide enough to be effective in reducing pollutants entering the water. The low-density development requirements of the North Carolina Stormwater Management Rules require a minimum buffer width of 30 feet between built-upon areas and the surface water; however, wider zones may be necessary to be effective.

    Setback requirements, discrete distances from water bodies or sensitive areas where construction is prohibited, are used to protect potable water supplies and other sensitive waters. Setbacks reduce pollutant loading of stormwater runoff and help avoid concentration of flood flows.

    Easements can be used to prevent development on land areas around water bodies. Although easements have not been used traditionally to protect water resources, they can provide an alternative method of gaining control of strategic land, especially in combination with buffer zones and setbacks. Easements may be negotiated or purchased from landowners and passed on to future owners as part of the deed to the property.

    Certain areas can be designated as strategic areas to receive long-term protection from development or other disturbances in order to maintain a high quality resource. The long-term protection could include purchase of the land or an easement, purchase of development rights, or some other type of agreement to limit development. Generally a local unit of government or one of its arms, such as a planning board or zoning commission or the soil and water conservation board, will declare an area to be a strategic area. Management of the strategic area is usually a responsibility of the governing body that declared the area to be a strategic area.

    "Green belts" around water ways can be used to protect the water and also provide parks and recreational areas for residents.

    Citizens can participate on zoning and planning boards to create rules requiring buffers in all new and existing developments. Buffer zones on homeowner's property or in subdivisions should be established (or left if already established) if the land borders a water body.

    Sanitary Waste Management. On-site sewage disposal, such as septic tanks and similar systems, can present a hazard to the health and well-being of residents and industries if these systems do not function as designed. If the on-site sewage disposal systems in the area are malfunctioning, the local governing body should consider the benefits of sanitary sewers. There are very few reasons not to connect to a sanitary sewer if one is available.

    If the need arises, areas that are found to be strategic to maintaining the quality of certain resources should be considered for installation of sanitary sewers. The availability of sanitary sewers can reduce or eliminate pollution that threatens receiving waters, however, sanitary sewer installation frequently brings increased development to an area. Local ordinances or zoning regulations must be in effect to control increased development of an area where sewers have been installed to reduce a pollution problem. Local governments should consider the installation of sanitary sewers for residential, industrial or commercial areas where on-site disposal poses health or environmental problems. Even occasional sewer or pumping station overflows can add significant amounts of pollutants to a receiving water, making the water unsafe for contact sports.

    Local governments should not use water and sewer pipeline installation to control development. The location and density of development should be controlled through strong planning and zoning programs rather than through the installation of water distribution and/or sewer collection systems.

    Local programs requiring proper on-site sewage disposal system installation and maintenance may control pollutants from a problem area. All on-site sewage disposal systems will operate better and longer if they are regularly inspected and cleaned.

    Local governments should pay special attention to the operation of small community sewage disposal systems to ensure they are operated by qualified personnel and maintained properly. Overflows from sewers and pumping stations can seriously pollute local streams.

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    Last Modified: 07/10/96