Asheville Ecological Services Field Office
Conserving the Nature of America





Design and Construction Recommendations

Preventing direct water contamination - Protecting the floodplain and streamside forest - Preventing or minimizing erosion - Stormwater management - Site and access road manamgement - Protecting migratory birds


Preventing direct water contamination – Water contamination can be one of a project’s most damaging and difficult-to- control environmental impacts. To avoid these impacts, we recommend:

  • Construction practices
  • • Refueling outside the 100-year floodplain or at least 200 feet from all water bodies (whichever distance is greater) and protecting the refueling area with secondary containmen
  • • Storing hazardous materials and other chemicals at an upland site outside the 100‑year floodplain or at least 200 feet from all water bodies (whichever distance is greater)
  • • Inspecting and maintaining equipment daily to prevent contamination from leaking fuels, lubricants, hydraulic fluids, or other toxic materials
  • • Keeping equipment out of streams
  • • Cleaning and checking equipment for leaks of hydraulic fluids, cooling system liquids, and fuel before fording any stream
  • • Preventing wet concrete from contacting water bodies
  • • Not using fertilizers and pesticides near streams or wetlands
  • Bridge design and construction
  • • Any new bridge design include provisions for roadbed and deck drainage to flow through a vegetated buffer large enough to alleviate any potential effects from the runoff of storm water and pollutants
  • • Any bridge demolition occur at low flow
  • Pipelines
  • • Installing utility line crossings perpendicular to the stream
  • • Periodic inspection and maintenance of utility lines to prevent discharge to land or surface waters
  • • Considering aerial crossings or horizontal directional boring under streams as alternatives to conventional “open trench” stream crossing methods
  • Wastewater treatment
  • • Using ultraviolet disinfection for wastewater effluent as chlorine is toxic to many kinds of aquatic life, and the reaction of chlorine with organic material in water can form carcinogenic compounds.
  • • Using treated wastewater effluent, where appropriate, to irrigate agricultural land and urban green spaces rather than immediately returning it to the stream

Protecting the flood plain and streamside forest - Streamside forests provide travel corridors and habitat for wildlife, stabilize stream banks, and filter storm‑water runoff. Floodplain development increases the potential for flooding adjacent properties and interferes with natural hydrological processes. In order to protect these important and sensitive stream-side areas, we recommend:

  • Riparian areas
  • • Limiting activities in the floodplain to those absolutely necessary for construction.
  • • Maintaining riparian vegetation to the maximum extent possible, especially large trees
  • • If riparian areas are disturbed, revegetating them with native species as soon as possible
  • • Locating areas used for borrow or construction by‑products away from wetlands and out of the 100-year flood plain.
  • • Maintaining forested wetland/stream buffers (a minimum of 100 feet wide on perennial streams and 50 feet wide on intermittent streams; 200 and 100 feet, respectively, in watersheds that are home to federally threatened or endangered aquatic species) throughout the project area
  • • Keeping all utility crossings to a minimum, and all utility infrastructure out of riparian buffer areas
  • • Constructing sewer lines of ductile iron or a substance of equal durability in circumstances where minimum setbacks cannot be attained
  • • Keeping manholes or similar access structures outside the buffer areas
  • Bridge and culvert construction and design
  • • Using spanning bridges that do not constrict the stream channel for all permanent roadway crossings of streams and associated wetlands because they minimize impacts to aquatic resources, allow for the movement of aquatic organisms, and eliminate the need to fill and install culverts
  • • Designing bridges to not alter the natural stream or the stream‑bank morphology or impede aquatic life passage.
  • • Designing bridges and approaches to avoid any fill that will result in the damming or constriction of the channel or floodplain.
  • • Placing any piers or bents outside the bank‑full width of the streams.
  • • If spanning the floodplain is not feasible, installing culverts in the floodplain portion of the approaches in order to restore some of the hydrological functions of the floodplain and reduce high velocities of floodwaters within the affected areas.
  • • Using bottomless culverts if culverts are the only option, Bottomless culverts do not need to be buried, thereby minimizing adverse impacts to streams.
  • • Designing the culvert to allow for the passage of fish and other aquatic life
  • • Sizing the culvert to accommodate the movement of debris and bed material within a channel during a bank‑full event
  • • Maintaining sufficient water depth in the base‑flow barrel during low flows to accommodate fish movement
  • • Minimizing culvert length to the extent possible
  • • Installing alternating or notched baffles in a manner that mimics the existing stream pattern if culvert is longer than 40 linear feet
  • • In most cases we prefer that a bridge be replaced in place by constructing the new bridge through staged construction or by detouring traffic to existing off‑site routes

Preventing or minimizing erosion – While soil forms the foundation of life on land, in water it becomes a pollutant, smothering aquatic insects, mussels, and other life; rendering fish spawning areas useless; and damaging sensitive tissues, like fish gills. It also increases drinking water treatment costs for downstream users. To minimize the amount of soil that enters a stream during the construction of a project, we recommend:

  • • Installing all erosion‑control measures prior to starting ground‑disturbing activities.
  • • Frequently maintaining erosion-control measures.
  • • Returning approaches to preconstruction contours upon completion of the project, and planting the area with native grasses and tree species.
  • • Planting temporary (e.g., rye, grain, wheat, millet) or permanent herbaceous material to help control erosion immediately following any ground‑disturbing activity. Native annual small grains and herbs appropriate for the season are recommended.  Fescue‑based mixtures should be avoided.
  • • A stream-bank monitoring and maintenance program to stabilize stream banks throughout the life of this project.
  • • Clearing be minimized, and if grubbing is necessary, it should be done immediately before grading.
  • • Limiting ground disturbance to that which will be stabilized by the end of the work day.
  • • Instream work should be conducted “in the dry”, making use of temporary diversion structures or pump-around systems as appropriate.

Stormwater management – Any development associated with new sewer lines will create more impervious surfaces (such as roofs, roads, and parking lots), which collect pathogens, metals, sediment, and chemical pollutants and without proper planning, quickly transmit them to streams, lakes and wetlands. To address these secondary impacts of the project, we recommend:

  • • Minimizing the amount of impervious surface resulting from development associated with this project
  • • Developing an adequate plan for controlling and treating stormwater.
  • • Incorporating stormwater retention to allow for the slow discharge of stormwater, attenuating the potential adverse effects of storm‑water surges: thermal spikes; and sediment, nutrient, and chemical discharges.
  • • The use of low-impact-development (LID) techniques to treat storm‑water runoff. LID is a method of storm‑water management that allows for storm‑water and environmental controls to be incorporated into the landscape and infrastructure (e.g., green roofs, rain gardens, and grassed swales)

Site and access road management – To minimize the negative impacts of the construction area and maximize the potential habitat value, we recommend:

  • • Using woody debris and logs from site clearing to create brush piles at the edges of the cleared areas to improve habitat for wildlife
  • • Allowing cleared areas to develop into a brush/scrub habitat. Corridor maintenance should be minimized, and mowing should be prohibited between April 1 and October 1 in order to reduce impacts to nesting wildlife
  • • Establishing a mowing schedule that incorporates a portion of the area (e.g., one-third) each year instead of the entire project every 2 or 3 years
  • • Avoiding the removal of large trees at the edges of construction corridors

Protecting migratory birds - The Migratory Bird Treaty Act prohibits the taking, killing, possession, transportation, and importation of migratory birds, their eggs, parts, and nests, except when specifically authorized by the Department of the Interior.  To avoid impacts to migratory birds, we recommend:

  • • Inspecting the project area from March through September.  If migratory birds are nesting in the project area, impacting the nests should be avoided from March through September.
  • • If birds are discovered nesting  in the project area during years prior to the proposed construction date, measures should be developed to discourage birds from establishing nests during the construction season, or construction and demolition activities should be avoided during the nesting period.
  • Tower design and siting (birds are attracted to tower lights, especially red and flashing lights, which increases chances for bird-tower collisions)
  • • Building the structure less than 200 feet above ground level, avoiding requirements for tower lighting which would attract birds
  • • Building the structure without guy wires
  • • Using red or white (preferable) strobe lights instead of flashing lights
  • • Avoid the use of solid red or pulsating red warning lights at night, as birds are more attracted to red lights
  • • Using the minimum amount of lighting, the minimum intensity of lighting, and the minimum number of strobe flashes allowed with the minimum strobe flash duration under Federal Communications Commission/Federal Aviation Administration regulations
  • • Minimizing lighting for on‑ground facilities and ensure it points downward or is down‑shielded
  • • Illuminating the tower with additional daytime white strobes (in addition to the tower top) to increase daytime visibility
  • • Collocating equipment on existing towers
  • • Siting new towers within existing tower clusters
  • • Siting towers away from wetlands, other known bird concentration areas
  • • Siting towers outside areas with a high incidence of fog, mist, or low ceilings
  • • Constructing towers so they can accommodate possible future collocations of antennas


Note: Fish & Wildlife Service project planning and review is coordinated by the Asheville Field Office in the western half of North Carolina and by the Raleigh Field Office in the eastern half.

Map: Asheville and Raleigh Field Offices work areas. Credit: USFWS Link to Raleigh Field Office web site


The North Carolina Wildlife Resources Commission has developed a A Guidance Memorandum to Address and Mitigate Secondary and Cumulative Impacts to Aquatic and Terrestrial Wildlife Resources and Water Quality. The memorandum provides numerous recommendations to address the environmental impacts that may result from a project. We support this document and encourage you to use it.

Photo montage of biologists shocking for fish, a biologists studying a plant, and biologists recording mussel data. Photo credits: U.S. Fish & Wildlife Service



Project planning and review contacts:

Address for all:
160 Zillicoa St.
Asheville, NC 28801

Holland Youngman
Projects involving the North Carolina Department of Transportation or Federal Highway Administration

Lauren Wilson
Projects involving the North Carolina Department of Transportation or Federal Highway Administration

Rebekah Reid
cell - 828/782-0090
Project planning and review

Byron Hamstead
office - 828/258-3939, ext. 42225

cell - 828/337-2726
Projects involving the U.S. Army Corps of Engineers

Bryan Tompkins
office - 828/257-3939, ext.42240
cell - 828 450-7586
Projects involving the Federal Energy Regulatory Commission, Tennessee Valley Authority, or Natural Resources Conservation Service



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Last Updated: July 13, 2016