Conservation buffers are small areas or strips of land in permanent vegetation, designed to intercept pollutants and manage other environmental concerns. Examples of buffers include: riparian/wetland buffers, filter strips, grassed waterways and vegetative barriers. An ordinance that requires buffers around water resources can effectively remove additional pollutants and protect downstream resources, as well as provide aquatic and terrestrial habitat. This fact sheet provides guidance on developing and implementing a buffer ordinance.
Buffers can provide many different environmental and economic benefits, including:
Water quality improvement and protection will vary based on the ordinance developed. An ordinance that requires a 100-foot buffer versus a 20 foot buffer will have higher pollutant removals. Pollutant removal studies have determined a 63-89 percent removal of TSS and 41-78 percent removal of TP for buffers that are between 4.6 and 26 meters wide (Aquatic Buffers Fact Sheet: Buffer Zones, Center for Watershed Protection).
MS4s can adopt regulations wherein owners or developers are required to implement buffers under certain conditions. Conditions could be based on proximity to streams, lakes and wetlands, to waters of the United States, to DNR public waters or based on the functions and values of water bodies as identified by the MS4. The EPA provides model ordinance guidance for buffers and recommends the ordinance framework adapted below.
Background Identify the functions and benefits of buffers.
Intent Establish the intent to require the design and implementation of buffer installations.
Definitions Define key terms.
Applications Identify the activities and applications to which the ordinance applies.
Plan requirements Identify the content and submittal requirement for the buffer plan.
Design standards Define the design standards including width or area, slope and vegetative cover. Establish a minimum width that would apply to all buffers, and then customize requirements according to functions, values, and perhaps size of the water body. Determine how areas are to be calculated and identify any flexibility in the standard, such as using an average buffer width to meet the standard. This would also allow changes to be made to adjust for such factors as steep slopes, poor soils, encroaching land uses or sensitivity of the water body. A State of Minnesota Stormwater Advisory Group document provides thorough guidance on wetland susceptibility which could provide a basis for required characteristics of wetland buffers (see Additional References). Standards should also provide specifications for different vegetative mixes based on a set of site conditions (e.g. slope, soils and climatic region), require signage, and specify a minimum spacing of signage (ex. every 50 feet) to identify the buffer and prevent encroachment. Especially in early spring, the untrained eye can mistake buffers for lawn.
See the Vegetated Swales and Buffer Strips fact sheet for additional design information.