Vegetated Buffers
In the July 21, 1999, Federal Register notice, we proposed to require the establishment and maintenance of vegetated buffers adjacent to waters of the United States as an alternative form of compensatory mitigation to ensure that activities authorized by NWPs result in minimal adverse effects on the aquatic environment. The vegetated buffer requirement was in the draft NWP 39 and the proposed modifications to General Conditions 13 and 19.
As a result of our review of the comments received in response to the July 21, 1999, Federal Register notice, we have made several changes to the vegetated buffer requirements for the NWPs. For example, vegetated buffers are required only if there are perennial or intermittent streams or other open waters on the project site. Vegetated buffers will be established and maintained on the uplands or wetlands next to the open waters. For the purposes of the NWPs, vegetated buffers are not required next to ephemeral streams or wetlands. The use of vegetated buffers as mitigation for NWP activities is discussed in General Condition 19. The changes to the vegetated buffer requirements are discussed in more detail below.
Many commenters supported the vegetated buffer requirements for the new and modified NWPs. A number of commenters stated that vegetated buffers should not be a condition of an NWP authorization. These commenters said that vegetated buffers should be considered only when a landowner voluntarily agrees to establish and maintain vegetated buffers adjacent to waters of the United States as an alternative form of compensatory mitigation. Several commenters contend that compensatory mitigation sites should be protected by vegetated buffers. Another commenter stated that the use of upland buffers should be consistent with current Federal guidance, particularly the "Federal Guidance for the Establishment, Use and Operation of Mitigation Banks" (60 FR 58605). A commenter stated that the vegetated buffer requirement should not apply to all activities that require a Corps permit, such as piers.
Vegetated buffers will be required only when there are open waters, such as perennial or intermittent streams, on the project site, and the NWP activity involves discharges of dredged or fill material into waters of the United States. However, a required vegetated buffer could be established off-site for impacts on the project site. Project proponents will not be required to establish and maintain vegetated buffers next to ephemeral streams. Vegetated buffers are not normally required for activities that require only Section 10 permits, but district engineers can require vegetated buffers as compensatory mitigation for activities authorized by Section 10 permits, if such compensatory mitigation is appropriate. District engineers will determine, on a case-by-case basis, whether or not vegetated buffers are required. Vegetated buffers are required only when it is practicable for the permittee to establish these areas and the vegetated buffer will be self-maintaining, other than restrictions on cutting or removal of the buffer. If the permittee does not own the land next to the open waters, then vegetated buffers are not required unless the permittee can reasonably obtain the appropriate conservation easements for those buffers.
Compensatory mitigation sites can be protected by vegetated buffers, but we do not agree that this should be a requirement of the NWP program. However, providing a buffer to the restored waters of the United States in a mitigation bank is precisely why a good mitigation bank will have a matrix of waters and uplands for maximum ecological functions and values. The "Federal Guidance for the Establishment, Use and Operation of Mitigation Banks" does not contain any useful guidance concerning the establishment and maintenance of vegetated buffers next to open waters. During the revision of the vegetated buffer requirements for the NWPs, we considered the riparian forest buffer Conservation Practice Standard (Code 391A) issued by NRCS in July 1997. We also considered the information in the document entitled "Riparian Forest Buffers: Function and Design for Protection and Enhancement of Water Resources" published by the Forest Service.
A large number of commenters opposed the vegetated buffer requirement. Those in opposition to this requirement were divided into two groups. One group objected to vegetated buffers as compensatory mitigation for discharges of dredged or fill material into wetlands because they believe that wetland losses should be compensated only through wetland restoration, creation, or enhancement. The other group of commenters stated that the Corps does not have the regulatory or statutory authority to require vegetated buffers adjacent to waters of the United States.
Those commenters that oppose the use of vegetated buffers as compensatory mitigation for losses of wetlands indicated that vegetated buffers adjacent to waters of the United States do not replace the lost functions that would be provided by wetland restoration or creation. Many of these commenters said that vegetated buffers next to open waters and streams do not provide flood storage capacity, wildlife habitat, water quality, or groundwater recharge functions. Numerous commenters stated that using vegetated buffers as compensatory mitigation will not help the Administration achieve its goal of a net gain of 100,000 acres of wetlands per year. Other commenters indicated that vegetated buffers as compensatory mitigation is contrary to the "no net loss" goal. One commenter said that the use of vegetated buffers is contrary to the 1990 mitigation MOA.
Vegetated buffers next to streams and other open waters on the project site are an important type of compensatory mitigation that provides substantial aquatic habitat, water quality, and flood storage benefits. The establishment and maintenance of vegetated buffers may be a preferable form of compensatory mitigation because it may be infeasible to create or restore wetlands on the project site after the activity is built. Vegetated buffers, even if they are established on uplands next to streams and other open waters, would provide on-site aquatic habitat, water quality, and flood storage functions.
Vegetated buffers next to streams and other open waters provide many of the same functions that wetlands provide. In fact, many vegetated buffers will be wetlands. Due to their proximity to open waters, vegetated buffers are more effective at protecting open waters than wetlands distant from those open waters. We have refined the following list of the functions of vegetated buffers from the list of functions published in the July 21, 1999, Federal Register notice. In general, vegetated buffers next to streams and open waters provide the following functions: (1) Reduce adverse effects to water quality by removing nutrients and pollutants from surface runoff; (2) reduce concentrations of nutrients and pollutants in subsurface water that flows into streams and other open waters; (3) moderate storm flows to streams, which reduces downstream flooding and degradation of aquatic habitat; (4) stabilize soil (through plant roots), which reduces erosion in the vicinity of the open waterbody; (5) provide shade to the waterbody, which moderates water temperature changes and provides a more stable aquatic habitat for fish and other aquatic organisms; (6) provide detritus, which is a food source for many aquatic organisms; (7) provide large woody debris from riparian zones, which furnishes cover and habitat for aquatic organisms and may cause the formation of pools in the stream channel; (8) provide habitat to a wide variety of aquatic and terrestrial species; (9) trap sediments, thereby reducing degradation of the substrate that provides habitat for fish and other aquatic organisms (e.g., some fish species depend upon gravel stream beds for spawning habitats); and (10) provide corridors for movement and dispersal of many species of wildlife. In addition, vegetated buffers next to streams provide flood storage capacity and groundwater recharge functions.
Although we are requiring the establishment and maintenance of vegetated buffers in uplands next to open waters as compensatory mitigation for certain activities, we expect to continue our documented programmatic no net loss of wetlands approach to the regulatory program. For most activities authorized by NWPs, vegetated buffers will only be a portion of the required compensatory mitigation. Moreover, where the project involves filling wetlands, vegetated buffers will only be required after a 1:1 ratio based on acreage of wetland mitigation has been required. Only 1/3 of the additional mitigation required for the project may be non-wetland vegetated buffers. The vegetated buffer requirement for the NWPs is not contrary to the 1990 mitigation MOA, because vegetated buffers next to open waters help achieve the goals of the Clean Water Act. It is also important to note that the 1990 mitigation MOA applies only to activities subject to the standard permit process.
One commenter requested clarification as to where vegetated buffers must be located. A few commenters disagree with the Corps position that vegetated buffers adjacent to waters of the United States provide benefits for the aquatic environment. One commenter requested that the Corps explain why vegetated buffers are necessary and specify the goals that will be accomplished by vegetated buffers. This commenter said that the goals of vegetated buffers will affect width requirements. This commenter also believes that not all areas adjacent to open waters provide significant benefits to water quality and that all vegetated buffers do not perform all 10 functions listed on page 39274 of the July 21, 1999, Federal Register notice, because the functions of vegetation buffers are dependent on the vegetation present and site and soil characteristics.
For the purposes of the NWPs, vegetated buffers are to be established and maintained on uplands or wetlands next to perennial and intermittent streams and other open waters. The functions and values of vegetated buffers next to open waters, especially forested riparian zones next to streams, are well documented in the scientific literature. The main goal of the vegetated buffer requirement is to restore, enhance, and protect open waters. In general, properly designed and implemented vegetated buffers, especially those inhabited by trees, will perform the functions listed above. Since we are not requiring vegetated buffers next to ephemeral streams, most vegetated buffers should have adequate amounts of water to naturally establish and support trees in the riparian zone. Vegetated buffers will normally be 25 to 50 feet wide on both sides of streams, but the district engineer can require wider vegetated buffers to address documented water quality concerns. A 25 to 50 foot wide vegetated buffer next to a stream provides important aquatic habitat functions and values, as well as substantial water quality benefits.
Many commenters believe that the vegetated buffer requirements for the new and modified NWPs exceed the Corps regulatory authority. Several commenters consider the vegetated buffer requirement as an attempt to expand the scope of the Corps jurisdiction to uplands. Numerous commenters indicated that the Corps is requiring vegetated buffers even if the work does not involve discharges of dredged or fill material into waters of the United States. Many commenters said that any vegetated buffer requirements should be imposed by the states, who have authority under Section 401 of the Clean Water Act to address water quality issues. Several commenters said that vegetated buffers could also be imposed by states through the requirements of the National Pollutant Discharge Elimination System program.
The Corps has the statutory authority to require vegetated buffers next to streams and other open waters because the goal of the Clean Water Act is to restore and maintain the chemical, physical and biological integrity of Nation's waters. This goal is stated in Section 101 of the Clean Water Act and is applicable to all sections of the Clean Water Act, including section 404. Vegetated buffers next to streams and other open waters help maintain the chemical, physical, and biological integrity of these waters. The establishment and maintenance of vegetated buffers next to streams is the restoration of riparian zones. Discharges of dredged or fill material into waters of the United States, which the Corps regulates under section 404 of the Clean Water Act, result in the loss of aquatic resource functions and values. The establishment and maintenance of vegetated buffers next to streams and other open waters offsets losses of aquatic resource functions and values and reduces degradation of these aquatic resources.
The vegetated buffer requirement is not an attempt to expand the Corps regulatory jurisdiction. We are not asserting jurisdiction over uplands next to streams and other open waters. We cannot require compensatory mitigation for upland impacts, but we can require, as compensatory mitigation, upland vegetated buffers that restore or protect aquatic habitat and water quality. The establishment or maintenance of a vegetated buffer next to waters of the United States can be an important part of the compensatory mitigation required for a Corps permit. The establishment and maintenance of vegetated buffers next to open waters can be considered as compensatory mitigation that offsets losses of waters of the United States and ensures that the adverse effects of the authorized work on the aquatic environment are minimal. Vegetated buffers are not normally required for activities that do not involve discharges of dredged or fill material into waters of the United States. For example, vegetated buffers are not required for structures in navigable waters of the United States, unless the district engineer determines that such compensatory mitigation is necessary to offset impacts to those waters.
Vegetated buffers next to streams and other open waters do more than protect water quality. Eight of the 10 functions listed in the July 21, 1999, Federal Register notice relate to aquatic habitat. Only two functions listed in that notice exclusively addressed water quality functions. Likewise, most of the functions of vegetated buffers listed in this Federal Register notice are aquatic habitat functions. Commenters objecting to the vegetated buffer requirement focused only on the water quality functions of vegetated buffers, and ignored the aquatic habitat functions.
A number of commenters stated that the vegetated buffer requirement duplicates, and may conflict with, local land use planning. Two commenters said that the vegetated buffer requirement is contrary to 33 CFR 320.4(j)(2), which states that the primary responsibility for zoning lies with state, local and Tribal governments. Many commenters believe that the vegetated buffer requirement constitutes a taking of private property. Two commenters said that the vegetated buffer requirement has the potential to result in a taking of private property because the Corps has failed to demonstrate the causal link between the vegetated buffer requirement and specific water quality concerns caused by discharges of dredged or fill material into waters of the United States authorized by the NWPs. These commenters assert that the Corps must allow alternative methods to address water quality concerns.
The vegetated buffer requirement does not duplicate or conflict with local land use planning. Although some state and local governments have vegetated buffer requirements, there are many regions that do not have such requirements. The district engineer will consider state and local vegetated buffer requirements when determining the vegetated buffer requirements for NWP activities. If the state or local vegetated buffer requirements are adequate, then the district engineer can defer to those requirements. The vegetated buffer requirement is not contrary to 33 CFR 320.4(j)(2) because it does not override state or local zoning decisions. If it is impractical for the permittee to establish and maintain vegetated buffers next to open waters on the project site, then vegetated buffers are not required. If the project proponent does not want to establish and maintain vegetated buffers and the district engineer determines that such buffers are necessary to ensure the proposed work results in minimal adverse effects on the aquatic environment, then the project proponent can request an individual permit or other form of DA permit.
The vegetated buffer requirement does not constitute a taking of private property because it is compensatory mitigation to offset losses of aquatic resource functions and values. If the project proponent does not want to establish and maintain vegetated buffers next to open waters on the project site, then he or she can request another form of DA permit to authorize the activity. The removal of nutrients, sediments, and pollutants from surface and shallow subsurface waters by vegetated buffers next to open waters is well documented in the scientific literature. The establishment and maintenance of vegetated buffers is a type of out-of-kind compensatory mitigation to offset authorized losses of wetlands and other waters of the United States, which also remove these chemical compounds from waters. The vegetated buffer requirement is no different than requiring the alteration of uplands to create wetlands as compensatory mitigation for losses of wetlands. In fact, the establishment and maintenance of vegetated buffers next to streams and other open waters is likely to be more successful and less costly than attempting to create wetlands by grading and altering uplands. When reviewing compensatory mitigation proposals, district engineers can consider alternative forms of compensatory mitigation to address water quality concerns, if vegetated buffers are not practical for the project site.
Several commenters opposed the vegetated buffer requirement, stating that it substantially reduces the amount of developable area on a parcel of land. Two commenters said that the vegetated buffer requirement will be difficult to implement for those projects that have already received subdivision approval. These commenters also assert that this requirement will increase the cost of housing. Several commenters said that the establishment and maintenance of vegetated buffers is practical only in large, open spaces. One commenter stated that the vegetated buffer requirement will increase sprawl development because it requires buildings to be constructed farther apart from each other.
Although the vegetated buffer requirement may reduce the amount of developable land on a particular parcel, we do not agree that such a reduction will be substantial. In most situations, vegetated buffers will be located in 100-year floodplains, in which there are often state or local building restrictions. If it is impractical for the project proponent to establish and maintain vegetated buffers on the property because of prior subdivision approval, then the district engineer can determine that vegetated buffers are not required. We do not agree that the vegetated buffer requirement will increase the cost of housing more than any other type of compensatory mitigation requirement, such as the creation of wetlands. In most circumstances, establishing and maintaining vegetated buffers will be less costly than grading land to create wetlands. The vegetated buffer requirement will not encourage sprawl development.
One commenter believes that the Corps needs to provide a cost-benefit analysis for the vegetated buffer requirement. This commenter also stated that this requirement requires an environmental impact statement because it is a major Federal action.
The vegetated buffer requirement does not need a cost-benefit analysis or an environmental impact statement.
In the July 21, 1999, Federal Register notice, we stated that vegetated buffers will normally be 50 to 125 feet wide, but provided district engineers with the flexibility to impose narrower or wider vegetated buffers. Many commenters stated that the widths of vegetated buffers required for NWP activities should be based on the width necessary to ensure that the adverse effects to the aquatic environment are minimal. These commenters said that permit conditions, including mitigation requirements, must be directly related to impacts of the proposed work and appropriate to scope and degree of those impacts. One of these commenters cited 33 CFR 325.4(a). Another commenter cited 33 CFR 320.4(r) and remarked that the Corps has not demonstrated that vegetated buffers provide compensatory mitigation for identifiable losses of resources. Numerous commenters said that the requirement for 50 to 125 foot wide vegetated buffers would, in some cases, result in compensatory mitigation requirements that would exceed the impacts of the activity. Two commenters disapprove of the vegetated buffer requirement, stating that it is not tailored to the effects of the authorized activity and could result in large vegetated buffers for projects that result in small losses of waters of the United States. Several commenters said that vegetated buffer requirements for particular projects must be in proportion of the impacts of the authorized work.
After considering these comments, we have reduced the recommended width of vegetated buffers to 25 to 50 feet wide on both sides of the stream or 25 to 50 feet from the OHWM or bank of the open waterbody. District engineers can require wider vegetated buffers if there are documented water quality concerns. The width of the vegetated buffer is measured in a direction perpendicular to the OHWM or bank of the open waterbody. The 25 to 50 foot wide vegetated buffer will provide aquatic habitat functions and values, as well as water quality benefits. When determining the appropriate width of vegetated buffers, district engineers will consider the degree of the adverse effects on the aquatic environment caused by the authorized work and require compensatory mitigation to the extent necessary to ensure that the adverse effects are minimal. The required compensatory mitigation, including vegetated buffers, will be in proportion, from an aquatic function and value perspective, to the authorized impacts to waters of the United States. If the authorized work results in minimal adverse effects on the aquatic environment without compensatory mitigation, then vegetated buffers are not required.
Two commenters said that the Corps should not specify a minimum width for vegetated buffers. One of these commenters contends that the benefits of vegetated buffers is likely to be different for dissimilar types of wetlands and waterbodies. One commenter requested clarification concerning the criteria that will be used to determine the width of vegetated buffers for specific project sites and which plant species should be used to establish the vegetated buffer. One commenter asked if a 50 to 125 foot wide vegetated buffer will be required in all cases. Two commenters recommended a minimum vegetated buffer width of 100 feet.
One commenter stated that many factors are cited in the current literature for determining the appropriate width of vegetated buffers. This commenter said that the Corps needs a standard method that district engineers can use to determine appropriate, site-specific vegetated buffer widths. This commenter also indicated that the width of the vegetated buffer should be based on the value of the aquatic resource to be protected and adjacent land uses. In addition, the method should identify situations where vegetated buffers are inappropriate or impractical. Several commenters said that the Corps should use a more flexible approach for vegetated buffer requirements, including the consideration of other methods that provide the same benefits, while utilizing less land. One commenter suggested methods to provide flexibility for vegetated buffer requirements, including buffer averaging to allow certain buffer areas to be narrower as long as the average width meets minimum requirements, conservation easements that can be donated to responsible charitable trusts and owner tax benefits, and density trading which allows developers density credits to offset loss of useable land to buffers.
We believe that recommending a 25 to 50 foot wide vegetated buffer and allowing district engineers the flexibility to determine appropriate vegetated buffer widths on a case-by-case basis is appropriate. A 25 to 50 foot wide vegetated buffer next to open waters will protect or restore aquatic habitat functions and values and provide water quality benefits. District engineers can require wider vegetated buffers if there are documented water quality concerns that can be addressed by a wider vegetated buffer. The district engineer will determine the appropriate width of the vegetated buffer on a case-by-case basis, based on the degree of impacts and the quality of waters. District engineers will also assess, on a case-by-case basis, whether or not vegetated buffers are impractical or inappropriate. District engineers can also consider the use of buffer width averaging. Density trading is more appropriately addressed by local planning and zoning agencies.
One commenter suggested using vegetated buffer width guidelines published by NRCS, which are based on soil type, slope, and topography. Two commenters stated that appropriate vegetated buffer widths should be determined by district engineers after consultation with Federal and state resource agencies. Two commenters requested that the Corps provide guidance for determining the length of the vegetated buffer along the open waterbody (i.e., how far upstream and downstream the vegetated buffer should extend).
We do not agree that it is necessary, for the purposes of the NWPs, to utilize complex vegetated buffer width guidelines based on soil types, slopes, and topography. Vegetated buffers 25 to 50 feet wide provide substantial aquatic habitat functions and water quality benefits. District engineers can require wider vegetated buffers to address documented water quality concerns or narrower vegetated buffers where it is not practicable to require 25 foot wide buffers. District engineers can coordinate with Federal and state resource agencies to determine the appropriate vegetated buffer width for a particular project, but we do not believe that this is necessary in all cases. The length of the vegetated buffer should extend along the open waterbody to the extent the district engineer determines necessary to offset authorized impacts.
Several commenters indicated that the guidance in the July 21, 1999, Federal Register notice concerning the width of vegetated buffers contradictory. For instance, General Condition 9 states that vegetated buffers must be established to the maximum extent practicable but there is a statement on page 39339 that says that the vegetated buffer should be as wide as possible. In addition, on page 39274 there is a statement that the width of the vegetated buffer must balance the benefits to environment with the uses of property resulting from authorized work. These commenters believe that the width of the vegetated buffer should be based on the benefits of the buffer and the adverse effects of the regulated activity (i.e., the discharge of dredged or fill material into waters of the United States), not all uses of the project.
We do not agree that the discussion of vegetated buffer requirements in the July 21, 1999, Federal Register notice contains contradictions. The appropriate width of a vegetated buffer is dependent on what is practicable for the prospective permittee and the amount of vegetated buffer that is necessary to ensure that the activity results in minimal adverse effects to the aquatic environment.
Several commenters said that vegetated buffers should not be required in all cases, particularly in those situations where the adverse effects on the aquatic environment are minimal. One commenter asked if vegetated buffers are required for activities that do not require notification to the district engineer. Another commenter asked if vegetated buffers are required even if the proposed work does not result in any impacts to streams, open waters, or wetlands on the project site. One commenter stated that vegetated buffers should be required only if there are perennial or intermittent streams on the site. Two commenters asserted that vegetated buffers should not be required next to ephemeral streams. One commenter stated that flexibility for district engineers to determine vegetated buffer widths reduces predictability for the regulated public when planning developments. Two commenters recommended that joint Federal agency guidance be developed for vegetated buffer requirements.
Vegetated buffers are not required if the proposed work results in minimal adverse effects on the aquatic environment without compensatory mitigation. Vegetated buffers are only required where the proposed project requires a Corps permit. The Corps is not establishing any new authority to regulate riparian areas, where no Corps permit is otherwise required. Vegetated buffers are not required for activities that do not require notification, since these activities result in minimal adverse effects on the aquatic environment. Vegetated buffers are required if there are open waters on the project site. We agree that vegetated buffers should not be required next to ephemeral streams. We will consider the development of joint guidance for vegetated buffer requirements.
Two commenters objected to requirements for conservation easements or deed restrictions for vegetated buffers. Another commenter supported the requirement for conservation easements or deed restrictions.
As with other forms of compensatory mitigation, conservation easements or deed restrictions for vegetated buffers are necessary to ensure that the compensatory mitigation site is maintained and protected from future alteration.
Three commenters requested clarification concerning how vegetated buffers are to be maintained and for how long vegetated buffers must be maintained. Two commenters stated that the requirement to maintain vegetated buffers is too burdensome for permittees because it implies that the permittees would have to monitor vegetated buffers and replace any vegetation that dies or is damaged during a flood or other storm event. One commenter indicated that the maintenance of vegetated buffers is problematic in arid regions because water would have to be provided to the plants to ensure their survival, which would be costly and contrary to water conservation policies. Two commenters suggested a limit of one year for the maintenance of vegetated buffers.
Permittees are not required to establish and maintain vegetated buffers that would require active management, such as irrigation. If the vegetated buffer must be planted, it must be self-sustaining, without the need for maintenance. Trees and shrubs damaged by storms and other events do not need to be replaced because the vegetation will grow back at the buffer site.
Two commenters supported the requirement for native species in vegetated buffers. Several commenters objected to requiring native species in vegetated buffers. One commenter said that this requirement is contrary to current best management practices because certain non-invasive, non-native plant species may be preferable in certain circumstances. Two commenters stated that the requirement for native species is unnecessary because there is no connection between water quality and the planting of native species or the removal of noxious weeds. Two commenters indicated that the requirement for native trees and shrubs in vegetated buffers is too strict and permittees should be able to plant native grasses and other herbaceous species instead of trees and shrubs. One commenter requested a list of "acceptable" native plant species for vegetated buffers.
Permittees are encouraged to plant vegetated buffers with native species, but this is not an absolute requirement. Vegetated buffers should be planted with native species, but a well-established vegetated buffer that contains some non-native species should not be removed and replaced. We recognize that there are circumstances where non-native species may be more appropriate. The planting of native species is important for the habitat functions of vegetated buffers. We encourage permittees to plant seedlings and saplings of trees in the vegetated buffer, but permittees can plant herbaceous vegetation in the vegetated buffer and allow natural succession processes to allow a woody plant community to develop at a later time. We do not agree that it is necessary to provide a list of "acceptable" native species that should be planted in vegetated buffers.
One commenter requested clarification whether vegetated buffers must be grassed or wooded. Another commenter objected to wooded vegetated buffers because they would impede flood flows and increase erosion. One commenter stated that wooded vegetated buffers would cause a loss of hydraulic capacity of the channel.
Vegetated buffers should have woody vegetation because woody plants, especially trees, are important components of an effective vegetated buffer. Woody plants, especially trees, provide shade to the open waters, as well as substantial amounts of detritus that is an important component of aquatic food webs. Woody vegetation in riparian zones often slows the velocity of floodwaters, which can provide water quality benefits by allowing sediment to drop out of suspension and decrease the sediment load in the water column. We do not agree that vegetated buffers increase erosion. The roots of woody vegetation help stabilize the soil, thereby decreasing erosion. Although woody vegetation, especially tree falls that create snags, may reduce the hydraulic capacity of a stream channel, it is important to consider the ecological functions and values of the stream, not just the hydraulic capacity of the stream channel and water conveyance. With the new and modified NWPs, we are placing greater emphasis on protecting open waters, especially streams.
One commenter supported the Corps statement in the July 21, 1999, Federal Register notice that mowed lawns are not considered vegetated buffers. Several commenters objected to this statement and believe that mowed lawns should be considered vegetated buffers.
We do not consider mowed lawns next to streams and other open waters as vegetated buffers because mowed lawns do not provide most of the functions and values that a vegetated buffer inhabited by trees or shrubs would provide. For example, mowed lawns cannot shade streams to moderate water temperature changes or produce woody debris that creates important aquatic habitat. In many areas, mowed lawns are intensively managed through the application of fertilizers, herbicides, and pesticides. Intensively managed mowed lawns next to streams can exacerbate water quality problems that vegetated buffers are intended to address. Since mowed lawns next to streams and other open waters do not provide the functions and values that wooded vegetated buffers provide, it would be inappropriate to consider mowed lawns next to streams and other open waters as compensatory mitigation for activities authorized by NWPs.
One commenter said that the requirement for vegetated buffers is inconsistent with the proposed NWP definitions. For example, the definition for the term "compensatory mitigation" does not include vegetated buffers that are established and maintained on uplands next to streams and other open waters. This commenter also contends that vegetated buffers cannot be considered enhancement because the proposed NWP definition for this term is limited to activities in aquatic habitats that increase one or more aquatic functions.
The establishment and maintenance of vegetated buffers next to streams and other open waters as compensatory mitigation is not inconsistent with the definition of the term "compensatory mitigation" provided in the "Definitions" section of the NWPs. The planting of trees and shrubs next to a stream in a pasture enhances the quality of the stream. Stream restoration activities usually involve planting the upland or wetland riparian zone with trees and shrubs. We have added a definition of the term "vegetated buffer" in the "Definitions" section of the NWPs.
One commenter requested that the Corps provide guidance concerning the specific amount of vegetated buffer that will be required as compensatory mitigation to offset losses of waters of the United States. Two commenters stated that vegetated buffers should be an additional requirement after the permittee has provided full compensation for wetland losses. A commenter asked if vegetated buffers alone can be used to satisfy compensatory mitigation requirements for the NWPs. This commenter also stated that, in many cases, vegetated buffers already exist on site and that the preservation of these areas is strongly discouraged by Corps mitigation policy because of the "no net loss" goal. This commenter believes that the vegetated buffer requirement is contrary to Corps mitigation policy.
We have modified General Condition 19 to provide guidance regarding the proportion of compensatory mitigation that should consist of vegetated buffers. If there are open waters on the project site and the district engineer requires compensatory mitigation for wetland impacts to ensure that the net adverse effects on the aquatic environment are minimal, any vegetated buffer will comprise a portion or all of the remaining compensatory mitigation acreage after the permanently filled wetlands have been replaced at a one-to-one acreage basis. By using vegetated buffers as compensatory mitigation, the quality of open waters will be protected or enhanced by maintaining these vegetated areas if they already exist on the site. If the vegetated buffer is not used as compensatory mitigation, then the permittee could cut down the existing vegetation next to the open waters (which often does not require a DA permit), which would adversely affect the quality of the open waters. Programmatically, the Corps will continue to support the "no net loss" goal for wetlands, but the establishment and maintenance of vegetated buffers for NWP activities will provide substantial benefits for open waters, especially streams.
Many commenters stated that the vegetated buffer requirement is problematic for companies and agencies that do not own the property where the vegetated buffer would be located on the project site. For example, the authority of flood control agencies is often limited to the channel, not to the land adjacent to the channel. As another example, utility companies have limited easement rights in utility line rights-of-way and cannot impose deed restrictions or conservation easements in these areas. Numerous commenters said that vegetated buffers should not be required where the project proponent does not own the land next to the open waters on the project site. Several commenters stated that the costs for public agencies to obtain rights-of-way to establish and maintain vegetative buffers will be prohibitive or economically impractical.
District engineers will not normally require vegetated buffers next to streams and other open waters if the permittee does not own the land next to the open waterbody. Such vegetated buffers will only be required where the permittee has or can reasonably obtain the appropriate conservation easements. Likewise, vegetated buffers are not required in utility line easements. However, if the utility company is building a substation on its land and there are open waters on the project site, the district engineer can require vegetated buffers next to those open waters as compensatory mitigation.
Two commenters said that vegetated buffers are impractical in urban areas where most of the surface runoff is directed to storm drain pipes, not streams. A commenter stated that maintaining vegetated buffers adjacent to facilities built by developers but handed over to local governments would increase costs to those local governments. Another commenter said that the vegetated buffer requirement will increase project and maintenance costs for state Department of Transportation projects. Two commenters assert that the vegetated buffer requirement will make maintenance of authorized facilities difficult or prohibitive. One commenter requested clarification whether a vegetated buffer disturbed during a maintenance activity will require additional mitigation or whether the project proponent would be required only to replace the disturbed vegetation.
If it is impractical to establish and maintain vegetated buffers next to streams in urban areas because of the limited amount of available land, then vegetated buffers are not required. In these circumstances, off-site compensatory mitigation may be preferable, including off-site vegetated buffers. If vegetated buffers next to open waters would make the maintenance of facilities in waters of the United States too costly, then other forms of compensatory mitigation should be considered. We do not agree that the vegetated buffer requirement would increase costs for transportation projects, because these activities usually require compensatory mitigation. If it is necessary to disturb the vegetated buffer during maintenance activities, the project proponent is only required to allow the vegetation to grow back. Additional compensatory mitigation will not be required for the disturbance of a vegetated buffer if it is allowed to grow back.
Several commenters said that vegetated buffers should not be required for activities authorized by NWPs 3 or 12. One commenter indicated that vegetated buffers should not be required for linear transportation crossings that are constructed perpendicular to the stream. Another commenter said that vegetated buffers should not be required for flood control maintenance activities.
District engineers can require vegetated buffers for activities that involve discharges of dredged or fill material into waters of the United States if there are open waters on the project site. Activities authorized by NWP 3 typically do not require compensatory mitigation, including vegetated buffers. There may be circumstances where vegetated buffers will be required for utility line activities, if compensatory mitigation is necessary to ensure that the adverse effects on the aquatic environment are minimal. Activities authorized by NWP 31 usually would not require vegetated buffers, especially if the flood control authority does not own the land next to the flood control facility or compensatory mitigation was required for the construction of the facility or previous maintenance activities.
Top of Page I Previous Page I Front Page