Chapter 2.1
Floodplain and River Corridor Land Use

• ALL
• Remove Code Barriers
• Create Incentives
• Fill Regulatory Gaps

Setbacks Protecting Sensitive Habitats and Water Quality

INTRODUCTION

A setback is an on-site building restriction that sets the minimum distance a building may be from a designated area, such as a sidewalk or street. Increasingly, building setbacks are also established to protect environmentally sensitive areas or critical wildlife habitat areas, including littoral and riparian areas, wetlands, forests, habitats for certain species, and shorelines.[1] The environmental characteristics of these areas are often irreplaceable, which makes setback requirements an important tool in protecting them from human impact.[2] Local governments can incorporate such setback requirements in their zoning ordinances, create incentives for those who leave sensitive areas untouched, or a combination of both.[3] When creating such setback requirements, local governments should be prepared for private landowners’ concern regarding use restrictions.[4]

One common type of setback requirement used by local governments are riparian buffer strips, a type of “conservation buffer” that can mitigate the damages of polluted runoff on water quality. The U.S. Department of Agriculture defines conservation buffers as “small areas or strips of land in permanent vegetation, designed to intercept pollutants and manage other environmental concerns.”^[5] Riparian buffer strips grow or are planted along the edge of surface waters, and intercept runoff from up-slope land use.^[6] Local government regulations typically limit or prohibit construction in these buffer areas and define allowable uses, usually low-impact activities such as walking or biking. Additionally, if development spills over or is found to have an adverse impact on the buffer or sensitive area, some local governments require that the developer or owner mitigate these damages through the replanting of native vegetation or other compensatory actions.

Local governments have great flexibility when it comes to establishing setbacks or buffers to protect sensitive areas. A key issue is often defining the width of the buffer.  In doing so, local jurisdictions, should at minimum consider the following factors to ensure habitat protection: purpose of the buffer, species present in the buffer, existing buffer conditions including natural resources and vegetative cover, slope, soil type, and surrounding land uses.[7] According to the Minnesota Department of Natural Resources (DNR), wider buffers provide greater control of pollution from runoff.^[8]  The Minnesota DNR also advises buffers containing deep-rooted grasses and native plants are most effective at preventing polluted runoff from reaching streams.^[9]

In addition, a U.S. Forest Service guide for the design of conservation buffers recommends that they be placed along a topographic contour to “promote shallow flow across the buffer” and prevent sections of the buffer at odds with the contour from becoming oversaturated with runoff.^[10] Buffer strips are particularly effective when planted along small streams, so it is important that municipalities ensure that these locations are not overlooked.^[11] More of the water that ends up in large, downstream waterways originates from these small streams than from runoff directly into the large waterway.^[12] Unfortunately, riparian buffers are less effective when utilized in regions where runoff occurs while the soil is frozen.^[13] Frozen soil is not effective at absorbing runoff.^[14] Many ordinances also provide for one or two additional development zones surrounding the traditional buffer zone itself, restricting development uses at consecutive levels.

EFFECTS

Setbacks and buffer zones shelter important natural resources and habitats from human impact. Not only are wetlands home to a number of different aquatic species, their associated buffers provide essential habitats for wetland dependent species, such as birds and certain mammals.[15] Additionally, riparian buffers can be home to many species of birds, mammals, amphibians, and reptiles.[16] Habitat buffers, along with sufficiently wide riparian and wetland buffers, can serve as wildlife migration corridors. “Wildlife have varying spatial requirements to maintain viable populations for survival,” and by establishing buffers, communities can reduce competition and maintain populations.[17] These migration corridors also combat habitat fragmentation, thus permitting the movement of wildlife and increased genetic diversity. [18]

Conservation buffers, especially riparian buffer zones, are important to improving water quality. Polluted runoff is a leading cause of water quality issues in the United States.^[19] On agricultural lands, nitrogen and phosphorous in fertilizers and manure, as well as pharmaceuticals in livestock manure, can leach into nearby waters via runoff, harming aquatic life and contaminating drinking water.^[20] In developed areas, rain and snowmelt runs across hard surfaces like roads and sidewalks, picks up pollutants, and drains into local waterways.^[21] In suburban areas, runoff can carry lawn and garden fertilizer away into waterways.^[22] And, in industrial areas, runoff can include hazardous pollutants such as wastewater from meatpacking facilities, chemicals from construction sites, heavy metals, and chemicals from vehicle maintenance facilities.^[23] Few, if any, communities are completely free of polluted runoff.

The Natural Resources Conservation Service (NRCS) states that conservation buffers are efficient at slowing this runoff, trapping pollutants, stabilizing soil, and controlling erosion.^[24] Ultimately, this translates to three principal benefits: (1) reduction of harmful impacts of polluted runoff, such as eutrophication of downstream waters; (2) improvement of the quality of drinking water in downstream waters; and (3) reduction of the cost of treating drinking water.^[25] The NRCS further states that when properly installed and maintained, conservation buffers have the capacity to remove up to 50 percent or more of nutrients and pesticides, 60 percent or more of certain pathogens, and 75 percent or more of sediment.^[26] Forested buffers have the added benefit of keeping water cool, allowing it to retain more dissolved oxygen.[27] They can also improve air quality by filtering dust from construction and farm activities.[28] Buffers around wetlands can serve many of the same functions as those around rivers or streams, with the added benefit of reducing rapid water level fluctuation in the wetlands.[29]

EXAMPLES

Fort Collins, CO

Fort Collins provides that any development within 500 feet of a natural habitat identified in the City’s Natural Habitats and Features Map Inventory, or any development containing a natural habitat or feature that has significant ecological value, is subject to the protection standards contained in the ordinance.[30] Among the natural habitats and features that hold significant ecological value are aquatic areas (e.g., rivers, streams, lakes), wetlands, and potential habitats and known locations of rare, threatened, or endangered species of plants and wildlife.[31]

The heightened protection standards that are part of this ordinance include buffer zones to protect the ecological character of natural habitats and features.[32] Buffer zones may be multiple and noncontiguous. The ordinance also provides general buffer zone distances that may be enlarged or reduced if necessary to comply with buffer zone performance standards.[33] For example, wetlands greater than a third of an acre and having significant use by water fowl and/or shorebirds have a general buffer of 300 feet, while lakes and reservoirs have a general buffer of 100 feet.[34] No disturbance is permitted in the buffer zones and if the development causes any disturbance, the developer is required to undertake restoration or mitigation measures. [35]

To view the provision, see Fort Collins, CO, Land Use Code § 3.4.1 (2017).

Maplewood, MN

Maplewood divides their wetlands into classes, each with distinct buffer and setback requirements. “Manage A” wetlands are wetlands with the highest function, “Manage B” are those of high quality, “Manage C” are of moderate quality, and Stormwater Ponds are ponds created for stormwater treatment.[36] Manage A wetlands, as well as streams, are required to have a minimum buffer width of 100 feet, while Stormwater Ponds have a minimum buffer of 10 feet, with an additional structure setback requirement of 10 feet from the edge of the buffer.[37] Additionally, this ordinance permits averaging of buffer widths when, due to the unique characteristics of the parcel, it is necessary to allow for reasonable use of the land.[38] In these instances, the minimum buffer width will be decreased, but a corresponding increase in width will be made elsewhere on the parcel.[39] In the case of Manage A wetlands, the minimum buffer width is decreased to 75 feet, but the average buffer width must still be 100 feet.[40]

Subject to certain exemptions, alterations and construction of structures is prohibited in wetlands, buffers, and streams. Further, the City requires mitigation when a property owner or contractor has altered or will alter a wetland or buffer.[41] Among the mitigative actions the City may require are “monitoring the impact and taking appropriate corrective measures”, and “compensating for the impact by replacing, enhancing or, providing substitute buffer land at a two-to-one ratio.”[42]

To view the provision, see Maplewood, MN, Code of Ordinances § 18-221 (2015).

Hartford, CT

Hartford, CT’s “Waterway Buffers” section of their zoning regulation aims

"to establish minimum acceptable standards for the design of waterway buffers in order to: protect riparian habitat; reduce land development impacts on water quality and flows; provide for the environmentally sound use of our natural resources; remove pollutants delivered in urban stormwater; reduce erosion and control sedimentation; prevent or minimize loss of life, injuries, property damage, and other losses; and furnish scenic value and recreational opportunity."^[43]

The zoning regulation works to meet these aims by restricting certain land uses near waterways which cause water safety or erosion hazards, and by preventing the destruction of natural barriers, stream channels, or flood plains.^[44] The zoning regulation prohibits parking, structures, and driveways in any floodplain in a 50-foot zone landward from the Connecticut River, in a 30-foot zone landward from any other waterway, and in a 25-foot zone landward from intermittent streams.^[45] Such buffer zones are to include vegetation, including trees, of “a type and quantity sufficient to protect the physical and ecological integrity of the waterway ecosystem, provide distance between upland development and the waterway, and filter stormwater runoff from land development.”^[46] Maintenance of the vegetation is to be maintained by, and not removed except for, a public body, but with removal of exotic and invasive species allowed for.^[47]

To view the provision, see Hartford, CT, Zoning Regulations § 6.11 (2018).

ADDITIONAL EXAMPLES

Surprise, AZ, Code of Ordinances § 122-12 (2009) (requiring an environmental buffer zone of at least 75 feet for natural habitats, features, and environmentally and culturally sensitives lands).

Sedalia, MO, Code of Ordinances §22-100-22-102 (2012) (ensuring “[r]iparian buffer zones shall remain undisturbed to the maximum extent practicable. This zone prohibits any land disturbance, clearing, grubbing or any other construction activities except as necessary for utility construction and road access. Such construction shall minimize disturbance of the stream and riparian buffer zone. Naturally occurring vegetation within the riparian buffer zone shall not be removed, diminished, inhibited, mowed, or substantially altered from its natural state or growth”).

Dover, DE, Code of Ordinances § 11.222 (2010) (requiring all buildings, structures, and impervious surfaces have a setback of at least 100 feet from wetland areas greater than .25 acres and from all water bodies).

Kansas City, MO, Zoning and Development Code §§ 88-415-01-88-415-09 (current through 2019) (providing for three continuous buffer zones of differing development standards around streams, with all buffer zones requiring “mature riparian vegetation”).

Shreveport, LA, Unified Development Code § 4.6(D) (2019) (creating three buffer development zones to “protect riparian (river and stream) corridors throughout the City of Shreveport. The buffer standards of the overlay district are intended to reduce soil and nutrient loss by slowing surface runoff, maintain the quality of water by reducing erosion and minimizing siltation, and provide a buffer to reduce sedimentation and nutrient pollution of streams and rivers from non-point sources”).

Atlanta, GA, Code §§ 74-300–74-321 (2012). (providing for different buffer widths depending on the type of body of water, including a requirement that development around any drinking water supply watershed area is set back at least 100 feet).

Seattle, WA, Municipal Code § 25.09.160 (2017) (establishing wetland buffer widths based on the size, category, and habitat functions of the wetland).

ADDITIONAL RESOURCES

Gary Bentrup, Conservation Buffers: Design Guidelines for Buffers, Corridors, and Greenways 21, Forest Serv.: S. Research Station (2008), https://perma.cc/VWZ2-P8AR.

Envtl. L. Inst., Planner’s Guide to Wetland Buffers for Local Governments (2008), https://perma.cc/T9S5-JWKA.

Minn. Dep’t of Nat. Res., Vegetation Buffer Strips in Agricultural Areas (Nov. 2007), https://perma.cc/K35G-T2PN.