decrease the amount of impervi- 

 ous or built-upon area allowed on 

 waterside property and establish 

 buffers along the estuarine 

 shoreline, as well as set different 

 standards for erosion control 

 permits. 



"'People said, 'Why do we 

 have this no-hardening rule on the 

 oceanfront but not in the estuar- 

 ies?'" says Bill Crowell, cumula- 

 tive impacts analyst for the 

 Division of Coastal Management. 



Oceanfront stabilization has 

 been prohibited since the late 

 1970s, when concern over beach erosion 

 prompted the Coastal Resources Commis- 

 sion to write regulations banning the 

 armoring of waterfront properties. Rigid 

 structures that extend into the water trap 

 sand from the longshore current and prevent 

 it from settling out on the properties 

 immediately "downstream," starving them 

 of sand. 



Water hitting bulkheads or seawalls 

 can also promote erosion during storms, 

 since the force of waves is transferred 

 downward and to either side of the structure. 

 Over time, the dry sand beach at the toe of a 

 bulkhead is eroded away. Hardened 

 shorelines also prevent the natural inland 

 and southward migration of beaches that 

 allows the Outer Banks to strike their 

 dynamic equilibrium with the sea. 



Now the Coastal Resources Commis- 

 sion is taking a long, hard look at shorelines 

 in the estuaries. While oceanfront regula- 

 tions are meant to preserve beaches for 

 public recreation, regulations for the 

 estuaries seek to preserve critical marshes 

 and intertidal areas that are the foundations 

 of coastal water quality and estuarine food 

 chains. Here, where fresh and salt water 

 mix, marsh grasses and an undulating 

 shoreline create a safe haven for juvenile 

 species such as blue crabs, shrimp and 

 striped bass. Ninety percent of commercial 

 fishing species and 65 percent of recre- 

 ational species spend some part of their lives 

 in estuaries, seeking shelter from predators 

 as they grow to maturity. 



Marshes and intertidal areas are 

 a critical habitat for many juvenile species. 



Marshes also absorb pollutants from 

 runoff and dampen the force of incoming 

 waves, lessening erosion. If shoreline 

 stabilization results in the loss of these 

 marshes, estuarine water quality declines 

 and many species lose a crucial habitat. 



The proposed rules seek to preserve 

 fringing marshes as much as possible and to 

 avoid the negative effects hardened 

 shorelines can produce. The proposed rules 

 from the Coastal Resources Commission 

 would establish a hierarchy of erosion- 

 control methods that ranks alternative 

 methods above the more traditional 

 bulkheading. "We're trying to tailor 

 shoreline stabilization methods to particular 

 sites using a tiered approach," Davis says. 



Under the proposed rules, Division of 

 Coastal Management field representatives 

 would visit sites to determine the erosion- 

 control method most compatible with the 

 location. Those with no erosion problems 

 would be prohibited from building hard 

 structures. For remaining sites, representa- 

 tives would inspect the landforms and water 

 characteristics at the site, including wave 

 energy and fetch. Fetch refers to the distance 

 waves can travel and build in size before 

 reaching the shoreline. 



In sites with sloping shorelines, 

 existing marshes or limited fetch, property 

 owners would be encouraged to plant marsh 

 grasses or cultivate the existing marsh to 

 anchor the shoreline and to dampen the 

 force of incoming waves. Areas with higher 

 wave energy or steeper shorelines might 



require breakwaters or stone in 

 addition to the marsh grasses, or 

 riprap revetments along a graded 

 bank. "We've proposed a new 

 general permit for riprap to make 

 it easier to install," Davis says. 



Vertical walls would only 

 be permitted in existing narrow 

 canals or locations where marsh 

 plantings or sloping structures 

 would not be practical for 

 erosion control. 



EROSION-CONTROL 

 OPTIONS 



Rigid structures in estuaries can have 

 negative effects. Like their oceanfront 

 counterparts, estuarine bulkheads promote 

 scour at the toe of the structure and 

 increase erosion of the unprotected land to 

 either side. They also reduce habitat for 

 juvenile animals that come to the estuaries 

 to mature. A 1995 study in Lake Conroe, 

 Texas, found far fewer juvenile and adult 

 fish in front of bulkheads than in front of 

 sloping riprap revetments. Riprap 

 structures, which have cracks and crevices 

 between rocks instead of a smooth surface, 

 provide a better habitat for animals but 

 prevent marshes from migrating inland just 

 as bulkheads do. Marsh grasses waterward 

 of any rigid structures are likely to be 

 drowned. The treated wood used to build 

 bulkheads also can transfer arsenic and 

 other toxic chemicals to the environment. 



Despite these shortcomings, rigid 

 structures and bulkheads in particular are 

 sometimes the best option for certain 

 shorelines. Spencer Rogers, coastal 

 construction and erosion specialist for 

 North Carolina Sea Grant believes the 

 environmental impact of erosion-control 

 structures is largely determined by their 

 distance from the water. 



"The toe of the structure should be as 

 far landward as possible to minimize its 

 impact" says Rogers. "Sloping structures 

 or revetments must be wide to function 

 properly, but narrow vertical structures 

 such as bulkheads can be readily moved 



26 WINTER 1999 



