Excavation of Channels, Canals and Boat Basins

Navigation channels, canals and boat basins are common along the coast's sounds, rivers and creeks. Navigation projects enhance our state's coastal waters for boating or fishing. But if they are poorly designed, navigation projects can disturb shellfish beds and fish nursery areas, damage wetlands or accelerate shoreline erosion.

You must meet the following specific development regulations for navigation channels {15A NCAC 7H .0208(b)(1)}, in addition to the general rules for coastal wetlands, estuarine waters and public trust areas: 

  • Navigation channels, canals and boat basins must avoid primary nursery areas, highly productive shellfish beds, beds of submerged aquatic vegetation and marshes.

  • Navigation channels and canals can be allowed through narrow fringes of regularly and irregularly flooded coastal wetlands, provided they do not significantly damage fishery resources, water quality or adjacent wetlands and if no reasonable alternative exists.

  • A canal or channel must be the smallest width possible to meet your needs and provide adequate water circulation.

  • Canals, channels and basins must not cause water quality problems. This standard ensures that water can flow freely, and won't stagnate and concentrate pollutants.

  • Canals and channels should be designed to prevent shoreline erosion on adjoining properties.

  • Septic tanks are not allowed on the shores of canals serving more than one residence, unless they meet standards set by the Division of Water Quality and the Division of Environmental Health. Such septic systems may not have point-source discharges, and the development must have stormwater routing and retention systems, such as grassed swales and settling basins. This reduces the discharge of sewage and other pollutants into canals, where water moves slowly and has a decreased capacity to dissipate harmful materials.

  • No canal or boat basin may be deeper than its connecting channels. Canals or boat basins deeper than adjoining channels can allow sediment and pollution to build up in the basin.

  • Boat basins should be designed with the widest possible opening and the shortest possible entrance to promote flushing and exchange of waters. The depth of a boat basin should decrease from the waterward end to the landward end (see Figure 4.6).

Figure 4.6

There are two common methods of excavating and maintaining navigation channels, canals and boat basins: mechanical dredging and hydraulic dredging.

Mechanical Dredging is used to construct and maintain navigation channels and boat basins, allowing boats to use coastal waters safely. But improperly placed dredged material (spoil) can smother coastal wetlands, shellfish beds and fish spawning and nursery areas, and can release pollutants into estuarine waters.

To qualify for a CAMA permit, your dredging project must meet the general CAMA regulations for coastal wetlands, estuarine waters and public trust areas. 

  • All dredged material from the construction or maintenance of a canal, channel or basin must be confined inland of regularly or irregularly flooded coastal wetlands and must be stabilized to prevent sediment from entering adjacent marshes or waterways.

  • Dredging in primary nursery areas and beds of submerged aquatic vegetation is prohibited, unless maintenance excavation is essential to maintain a traditional and established use in these areas. In order to conduct maintenance excavation in these areas: 

  • You must meet certain criteria, and you must present clear evidence that you can meet those criteria when you apply for a permit.
  • You must prove that the project is water-dependent, the channel has been continuously used for a specific purpose, and the disposal of dredged material will not harm coastal resources. 

Hydraulic Dredging

Because hydraulic dredging increases the potential for environmental impacts, special rules apply {15A NCAC 7H .0208(b)(2)}:

  • Dredged material (spoil) must be confined on high ground by retaining structures or deposited on ocean beaches if the spoil is suitable. Dredged materials confined on high ground must be placed inland of any marshland and should be stabilized to keep sediments from entering adjacent waters or wetlands.

  • The end of the dredge pipeline should be set far enough into the disposal area to keep the containment dike from eroding and far enough from the spillway to allow suspended sediments to settle evenly throughout the disposal area. (see Figure 4.7A).

  • Effluent from a diked spoil disposal area must be carried by a pipe, trough or similar device to a point in the water past visible vegetation or below the normal low water line. When possible, you must return effluent to the area being dredged (see Figure 4.7B).

  • A water control structure must be installed at the intake end of the effluent pipe to allow for the settling of suspended sediments, which restricts the flow of sediment into adjacent marshes and waterways (see Figure 4.8).

  • Effluent from diked disposal areas holding spoil from closed shellfish waters must not be returned to open shellfish waters. This practice keeps the contaminants found in closed shellfish waters from reaching non-polluted shellfish beds, spawning and nursery areas, and submerged vegetation beds.

Figure 4.7


Figure 4.8