Management Recommendations for Mussels

Habitat conservation has become a significant component of the Nongame and Endangered Wildlife Program's efforts to maintain viable populations of freshwater mussel and fish species. Threats to these species and their habitat include: misuse of fertilizers, pesticides and herbicides, toxic chemicals from point and non-point sources of pollution, habitat degradation from erosion and sedimentation, competition from exotic species and impoundment of free flowing streams and rivers. The pages below offer recommendations for the management of landscapes to help reduce impacts from these threats.

 

Make a selection below to learn more about management recommendations for freshwater mussels.

The removal of trees on land immediately adjacent to streams leaves aquatic habitats vulnerable to increases in water temperature and sedimentation, weakens the integrity of stream banks by reducing extensive, near-shore root networks and reduces the diversity of plant materials necessary for energy flow, nutrient cycling and structure within aquatic habitats.

In 1998, Champion International Corporation signed a Memorandum of Understanding (Champion MOU) (82kb PDF) to help conserve its woodland in the upper Tar River Basin. An associated support document (100 kb PDF) was prepared by Ann Prince with the NC Natural Heritage Program. The conditions of the Champion MOU are summarized below. These recommendations should be used in association with the draft forestry Best Management Practices (BMPs) manuals being developed by the NC Division of Forest Resources. The draft forestry BMP manuals can be acquired from the NC Division of Forest Resources at 919-733-2162. The mailing address is P.O. Box 29581, Raleigh, NC 27626-0581.

Recommendations

A forested riparian buffer should be maintained a minimum of 200 feet in width on each side of a stream. Within that buffer there should be a no-harvest zone that extends from the stream edge to a distance of 50 feet or to the top of the first levee, whichever is greater. The remaining buffer, approximately 150 feet, should be selectively harvested according to the provisions described below:

    • Avoid conversion of hardwood or mixed forests to pine.
    • Use single tree or small group selection to remove trees, ideally retaining an average of 70% canopy closure throughout the buffer, with no less than 50% closure in any specific location.
    • Avoid construction of new roads or right-of-way corridors within the buffer.
    • Avoid soil disturbance to the fullest extent possible.
    • Avoid use of herbicides, pesticides, or fertilizers.

To further enhance wildlife habitat suitability, additional recommendations are provided:

    • Retain den trees, mast-producing trees, and other tree species utilized by wildlife.
    • When there is a focus on significant bird or other populations, conduct tree harvest during the non-breeding season (October 1st to March 1st) when possible.
    • Keep existing road widths to a minimum (ideally, 25 feet wide or less) to reduce fragmentation.
    • Retain snags, especially those which do not protrude above the canopy and those which occur in clusters.

The overland movement of soil from farm fields into streams is one of the primary impacts to aquatic habitats from crop production. Contamination of water from misuse of pesticides, herbicides and fertilizers is another serious impact. As with silvicultural activities, the removal of trees on crop and pastureland immediately adjacent to streams leaves aquatic habitats vulnerable to increases in water temperature and sedimentation, weakens the integrity of stream banks by reducing extensive, near-shore root networks and reduces the diversity of plant materials necessary for energy flow, nutrient cycling and structure within aquatic habitats. High levels of nitrogen and bacterial contamination are impacts associated with livestock and confined animal operations. Direct access for livestock to streams also leads to erosion of stream banks.

Recommedations

A forested riparian buffer should be maintained a minimum of 200 feet in width on each side of a stream. Within that buffer there should be a no-harvest zone that extends from the stream edge to a distance of 50 feet or to the top of the first levee, whichever is greater. The remaining buffer, approximately 150 feet, can be selectively harvested according to the provisions described below:

    • Avoid conversion of hardwood or mixed forests to pine.
    • Use single tree or small group selection to remove trees, ideally retaining an average of 70% canopy closure throughout the buffer, with no less than 50% closure in any specific location.
    • Avoid construction of field access roads and field ditches within and through the buffer.
    • Avoid soil disturbance within the buffer to the fullest extent possible and employ Best Management Practices, such as no till farming, contour plowing, conservation tillage, and filter strips on fields.
    • Avoid use of herbicides, pesticides, or fertilizers in the buffer and minimize use on fields.

Several programs are available through your NC Soil and Water Conservation District Office to provide technical and financial assistance for implementing Best management practices such as forested buffers. The following information is reproduced from the United States Department of Agriculture, Natural Resources Conservation Service at http://www.nrcs.usda.gov/technical/.

Conservation Reserve Program (CRP) - This program allows you to establish certain conservation buffer practices on cropland and marginal pasture and enroll the land in the CRP at any time. Filter strips, field borders, grassed waterways, field windbreaks, shelterbelts, contour grass strips and riparian (streamside) buffers are all examples of conservation buffers. In addition to being common-sense practices, financial incentives make conservation buffers economically attractive.

Environmental Quality Incentives Program (EQIP) - This program provides technical, financial and educational assistance in designated priority areas, with half of the resources targeted to livestock-related natural resource concerns and the remainder set aside for other significant conservation priorities.

Wildlife Habitat Incentives Program (WHIP) - This is a voluntary program for landowners who want to develop and improve wildlife habitat on private land. It provides both technical assistance and cost sharing to help establish and improve fish and wildlife habitat.

Wetlands Reserve Program (WRP) - This voluntary program helps landowners restore and protect wetlands on private property. It provides an opportunity for landowners to receive financial incentives to enhance wetlands in exchange for retiring marginal agricultural land.

Stewardship Incentive Program (SIP) - Teamed with the Forest Stewardship Program, SIP provides cost sharing for improved management of private forest land through multiple practices, including planning, tree planting, wildlife and fish habitat, recreation, riparian restoration, soil erosion control, and forest improvements.

Some private organizations are making financial assistance available as well, particularly for wildlife habitat enhancements. We recommend you contact your NC Division of Soil and Water Conservation District representative (http://www.ncagr.gov/SWC/commission/CAC.html) for information on Best Management Practices associated with agricultural activities.

Roads are considered essential for the economic and social well-being of all modern communities. In general, easy access to well maintained major interstates, state highways and smaller secondary roads is considered essential infrastructure by most governments. The construction and maintenance of roads and bridges have major impacts on aquatic ecosystems. Sediment, hydrocarbons, various other toxic substances and increased stormwater flows are usually associated with roads. In most cases, these impacts to aquatic ecosystems can be dramatically reduced during all phases of road and bridge construction and maintenance activities.

Stormwater Management Associated with Roads

The focus of most stormwater management systems in the past has been the rapid transfer of water from roads to ditches with ultimate discharge directly to nearby draws, streams, creeks and rivers. Such a system increases driving safety for citizens; however, it increases sediment and toxicant loading to streams and increases scouring of stream banks and substrates by increasing stream flows above normally expected levels. Theoretically, all existing roads associated with aquatic endangered species habitats should be retrofitted as quickly as possible to significantly reduce stormwater transfer directly to waterbodies. However, such a process would cause undue economic hardship. Instead, during maintenance activities along roadways, whenever possible and practical, road maintenance crews should divert stormwater into the local landscape. Particularly along streams and creeks with flat riparian habitats, such actions would significantly reduce peak flows, increase infiltration, and reduce the introductions of toxicants. For new construction activities, such stormwater diversions should be required project actions.

Bridge Maintenance and Replacements

Over time, bridge structures age or become damaged and must be repaired or replaced to ensure public safety. Such a process can be accomplished with a nominal impact on the associated aquatic habitats and with reasonable cost modifications. Whether the project is a local bridge maintenance project or a major replacement project, it is essential that adequate communication, planning and design, and implementation occur at appropriate times during the life of the project. The following recommended protocols summarize strategies used in North Carolina to conserve aquatic endangered species' habitats. These recommendations represent more than 10 years of consultations among state and federal governmental agencies. These strategies were developed with full cooperation from numerous biologists, engineers, landscape professionals and other personnel from various state and federal agencies. In general, N.C. Department of Transportation personnel have taken great pride in their abilities to complete required construction activities while conserving extremely important aquatic habitats.

Recommended Protocol for Bridge Maintenance Projects

  • Adequate opinion from biologists experienced in minimization of project impacts to sensitive aquatic habitats should be acquired whenever bridge maintenance actions are being considered.
  • Whenever possible, maintenance actions should be accomplished during the growing season for local plant communities.
  • Lead-based paints should not be used on bridges.
  • Pesticides should not be used near bridges. Excessive amounts of fertilizers should not be used near the stream.
  • If fill near a bridge, stream bank management, or in-stream work is required, the project should be processed in the same manner as for a bridge replacement project (see below).

Recommended Protocol for Bridge Replacements

  • Adequate opinions from biologists experienced in minimization of project impacts to sensitive aquatic habitats should be acquired whenever bridge replacement actions are being considered.
  • In areas possibly occupied by aquatic endangered species, a survey for the species - 100 meters upstream and 300 meters downstream - should be conducted by a permitted biologist before construction begins. If the species is discovered in this project footprint, relocations upstream should be completed with cooperation from state and federal wildlife agency personnel.
  • State and federal wildlife agency personnel should be invited to any pre-construction conferences. These personnel should also be notified before construction activities begin.
  • All channel spans and bents from the existing bridge should be dismantled from the top down. No debris from the demolition of the existing bridge should be allowed to reach the stream. These activities help eliminate possible water and sediment disturbances caused by traditional structure removal techniques.
  • Whenever possible, piles from bents of the existing bridge in the stream channel should be cut off at the stream bed or natural ground elevation. Turbidity curtains or other appropriate means should be used to restrict movement of any sediment disturbed during this process. Piles from non-channel bents can be removed normally. When timber piles are to be cut off at stream level, a crane and bucket can be used to lower a construction worker down to stream level. The construction worker can then use a hydraulic saw to cut off the timber piles without affecting the stream.
  • On land, special soil and erosion control measures should be implemented to prevent sediment from entering the stream. These measures should be adequate to protect Outstanding Resource Waters. Measures should be in place before grubbing activities take place.
  • Pesticides should not be used near bridges. Excessive amounts of fertilizers should not be used near the stream.
  • All clearing and other soil disturbing activities should be limited to the time between April 15 and November 1. These activities should be scheduled to limit the duration and extent of soil exposure. No clearing should be done until just before other work is to begin in a specific area. Exposed areas should be seeded as soon as work in the area is completed.
  • Grubbing activities should be kept to a minimum throughout the project area. Grubbing in areas within 50 feet of the stream should not be allowed unless absolutely necessary for project construction. Clearing activities should be done by hand wherever feasible.
  • Ditching along the roadway should be designed and constructed to divert stormwater away from the stream.
  • Fill material, construction causeways, or construction equipment should not be allowed in the stream.
  • If site conditions permit, the new bridge should have pile bents. If site conditions dictate the use of drilled shafts, the slurry from drilling should not be allowed to enter the stream directly. The slurry should be pumped to a settling basin away from the stream bank to allow sediment to be removed.
  • Green concrete should not come in contact with the stream.
  • Whenever possible and practical, the bridge should be designed and constructed to span the stream.
  • Deck drains over the stream should be eliminated on the new bridge unless there are safety concerns. If eliminated, bridge drainage outlets should be located only on the approach spans. Rip rap should be placed under the bridge to catch and filter run-off from the bridge drainage outlets.
  • Granular fill material should be used in all fill areas immediately adjacent to the bridge to reduce the possibility of sediment reaching the stream during significant rainfall events.
  • If significant fill is required, contractors should be required to construct fill approaches using lifts not to exceed 4 feet. Each lift should be encased with stone (rip rap) plating on the slopes before a new lift is begun. When significant fill is required, a cloth fabric may be required to cover the exposed fill at night when the fill is not being placed or when a storm event is approaching the construction site.
  • During all phases of a project, motor fuels, lubricants, and other toxic substances should be kept at least 100 feet from the stream.

On the surface, these suggestions appear extensive; however, with proper planning and implementation, these recommendations often have nominal impacts on project costs and, on occasion, reduce overall project costs. This is particularly true when the number of bents can be reduced.

Recommended Protocol for Other Road Projects

In areas associated with aquatic endangered species habitats, all other road maintenance and construction activities should follow Best Management Practices required for the conservation of High Quality Waters.

Traditional land uses, such as silviculture, generally appear to provide the necessary stream buffers and hydrologic conditions to protect aquatic habitats. As North Carolina changes from a rural agricultural economy to a modern industrial center, extensive development is likely to change the current land and water use patterns. The cumulative and secondary impacts of development, including impacts from increasing numbers of bridges and culverts, numbers of wastewater spills and amount of impervious surfaces, can result in stream bank instability and other stream morphology changes, increased sediment loading, changes in substrate characteristics, modified aquatic food resources, changed stream temperatures, increased nutrient loading, increased toxicant loading, changed fish communities and reduced complexity of benthic habitats. These anticipated changes are known threats to sensitive aquatic species, such as freshwater mussels. Protective land and water use recommendations need to be implemented to reduce changes in aquatic ecosystems.

Recommended Protocols:

Stormwater

  • The natural predevelopment hydrograph should be maintained. It is important to determine the pre-development hydrographic regimes and stream temperatures to develop baseline data sufficient to determine future changes. Rosgen or similar geomorphologic methods should be used.
  • In order to maintain predevelopment hydrographic conditions, including flow volumes, new developments can build using traditional designs at a level of 7% imperviousness, or build more densely, using dedicated open space and other stormwater practices to mimic the hydrograph which would occur at only 7% imperviousness.
  • Maintain a 200-foot naturally forested buffer on all perennial streams and a 100-foot forested buffer on all intermittent streams in new developments. If wooded buffers do not exist, then these areas should be revegetated to allow development of a naturally forested buffer. (See Knutson and Naef 1997 for identified need for wide riparian buffers. Note 200-foot buffers associated with protection of aquatic endangered species habitats required for Buckhorn Reservoir Expansion Project in 1995.)
  • Infiltration practices (e.g., reduced road widths, rain gardens, parking lot bioretention areas, increased sheetflow instead of ditching, disconnect impervious areas) should be emphasized over detention ponds to maintain predevelopment hydrographic conditions, including base flow during low flow conditions.
  • Grassed swales should be used along streets in place of curbing and guttering, except in areas with >5% slope.
  • There should be no direct discharges of stormwater to streams, and stormwater should not be ditched or piped through the buffer.
  • Use of Conservation Reserve Program lands and restoration of prior converted wetlands should be encouraged to help manage overall stormwater impacts.
  • Local governments should encourage new developments, including residential, to use the planning method for stormwater control outlined by the EPA in their Low Impact Development manual (EPA Document # 841- B-00-002 and 841-B-00-003) and reduce impediments to implementing strategies promoted by the EPA in this manual. These documents may be obtained on-line at by searching for "Low Impact Development" at http://www.epa.gov/
  • Developers and builders, including land clearing operators, should participate in a stormwater education program.

Wastewater Treatment Facilities and Infrastructure

  • Design and implement spill and emergency management procedures for the removal and clean up of any spills and similar situations (e.g., runoff from efforts to control residential, commercial, or industrial fires) instead of utilizing "hosing down" or flushing practices.
  • Install ultraviolet or ozonation disinfection equipment to replace older disinfection technologies.
  • Eliminate package sewage treatment plants and provide incentives, such as reduced rate or free connections to public facilities, for users of existing package treatment plants.
  • For sewer lines closest to streams, public and private sewer lines should parallel streams and be at maximum distances from streams and tributaries. Between sewer lines and streams, a minimum 200' natural buffer should be provided for perennial streams and a 100' buffer for intermittent streams, using criteria defined by the US Army Corps of Engineers or other regulatory authorities, including the Division of Water Quality
  • No new sewer lines or structures should be installed or constructed in the 100-year floodplain nor within 50 feet of wetlands associated with the 100-year floodplain.
  • Sewer lines closest to streams should be constructed of ductile iron.
  • Only aerial or directional boring stream crossings should be allowed, and the placement of these crossings should be limited to major stream or creek confluences. Manholes or similar access structures should not be allowed between linked sewer lines. Stream crossing areas should be monitored once a quarter for potential maintenance needs. Sewer lines associated with crossing areas should be maintained at the highest standards possible.

Water, Gas, and Other Underground Utilities

  • To prevent direct impacts to important aquatic habitats, all underground utilities should follow requirements associated with sewer line placements.

Above Ground Utilities

  • Stream crossings should be reduced to the minimum number necessary to deliver electricity, telecommunications, etc. to the service area.
  • All utility crossings should be perpendicular to stream flow.
  • Pesticides (including insecticides and herbicides) should not be used within 200 feet of streams or floodplains and wetlands associated with streams.
  • Native forested plant communities should be maintained within 200 feet of streams or floodplains and wetlands associated with streams. On small streams, creeks, and rivers, a closed canopy should be maintained over streams. Emphasis should be placed upon trimming trees (instead of tree removal) within 200 feet of streams or floodplains and wetlands associated with streams.

Sediment and Erosion Control

  • State of the art erosion and sedimentation control measures should be implemented for all construction sites and should significantly exceed state minimum requirements.
  • Fill or building should not be allowed in the 100-year floodplain.