«Presented by the Carolina Environmental Program Morehead City Field Site Students: Joseph Hester, Alison Kitto, Elizabeth Newland, Erika Poarch, ...»
In 1972, the United States Government adopted the Federal Coastal Zone Management Act (CZMA). This required state governments to designate specific boundaries for their coastal zones, and to identify a host of natural features with particular environmental and ecological significance. The Coastal Area Management Act (CAMA) was passed by North Carolina legislators two years later in response to CZMA requirements (Finnell 1978). In an effort to standardize an inefficient system and adopt restrictive policies that involved general permits issued by the USACE, this legislation outlined the specific roles of local and state governments in coastal area development. The Coastal Resources Commission (CRC), under the jurisdiction of the North Carolina Division of Coastal Management (DCM) and the North Carolina Department of Environment and Natural Resources, is responsible for the scrutiny and approval of all permits for bulkhead construction in the coastal region (DCM 2003).
According to state law, local residents must apply to the CRC in order to build a shoreline stabilization structure. Under the permit process outlined by CAMA, permission to develop infrastructure in coastal areas is refused where proposed constructions would negatively impact the productivity of nearby land and water resources (DCM 2003). Current CRC policies prohibit the construction of a hard SHS within or immediately seaward of wetland habitats (Street et al. 2005). Additionally, they prohibit the infilling of any wetlands that may occur on the landward side of said SHS. Much like the general permits issued by the USACE, the CRC has issued a general permit allowing the enhancement of marshes via sill construction rather than bulkhead construction. However, that permit’s greatest obstacle exists in the stipulation that it cannot be utilized if there are “unresolved questions concerning the proposed activity’s impact on adjoining properties or on water quality, air quality, coastal wetlands; cultural or historic sites;
wildlife; fisheries resources; or public trust rights” (DCM 2003). CAMA is explicit in their recommendation to avoid bulkhead construction in situations where soft shoreline stabilization structures are appropriate. However, soft shoreline stabilization methods have never matched the prevalence of bulkheads and other SHS. Current policy changes are being formulated that will only allow the construction of a bulkhead in an area where erosion has been documented (Street et al. 2005).
This effort presents an interesting paradox, however, since bulkheads have been widely used for many years. Currently, the Coastal Resources Commission approves permits for about 30 miles of bulkhead per year (Skrabal, unpublished). As previously mentioned, a bulkhead on a property owner’s shoreline increases erosion on nearby natural shorelines. These situations, since erosion has already become a problem due to neighboring bulkheads, justify a CAMA permit for bulkhead construction. As a result of new policies, current bulkhead extent increases the need for bulkheads on adjacent properties. As more and more of these structures are installed, a vicious cycle is created where entire lengths of shoreline must be armored.
An important obstacle has hindered most shoreline hardening legislation from becoming proactive as opposed to reactive. Coastal development policies are designed to compensate for preexisting threats to the coastline (Holway and Burby 1993). It has also been suggested that increased shoreline hardening can provide landowners with an incentive to amplify development efforts (Burby et al. 2000). Current policies do not adequately limit development in areas susceptible to erosion as a proactive solution (Holway and Burby 1993).
One method of developing a proactive solution would involve setback lines, seaward of which no construction is allowed to take place. These setback lines could be identified in areas that are particularly sensitive to erosional or even sea level rise pressures. Appropriate local zoning regulations, also effective at preventing erosion problems, often include setback lines.
They can help create buffer zones by relocating preexisting infrastructure and acquiring waterfront properties in order to preserve them as public conservation areas. Local governments, with uniquely effective oversight for their municipal areas, are powerful tools that can help build small-scale coalitions based on the most up-to-date and comprehensive information (NRC 2006).
Their close contact with local developers and landowners allows them to adopt the most specifically appropriate measures to ensure erosion protection and ecosystem vitality.
Originally, the private encroachment on public trust areas was the main issue of concern in the shoreline hardening debate. Overall, what mattered to policymakers was whether or not shoreline alterations would affect areas over which the federal government maintained jurisdiction. The very nature of the effects private actions may have on public goods has changed; what was once considered an effect on navigability can now be considered an effect on biological productivity. The “takings clause” of the US Constitution claims that no amount of private property can be stripped by the government without just compensation to the original owner. Said clause has been redefined so as to account for any negative consequences certain private actions may have on the public good (Finnell 1978). Navigable waters have come to include all wetland areas below mean high tide line. This gives the federal government control over the important biological communities that are not directly valuable for the transport of material on ships, but which are inevitably valuable as resources that promote the ecological health of coastal waterbodies (Finnell 1978). Changes have also occurred in the problem’s perception by landowners, interest groups, and local decision-makers. Jurisdictional alterations have evolved to include concerns about wetland loss, fisheries, tourism, property values, and relative sea level rise.
Under most current legislation, policies are reactive, but efforts are being made to develop proactive policies for the protection of our coastal ecosystems. The North Carolina Division of Coastal Management’s Estuarine Shoreline Subcommittee, established in 2000 under CAMA, has identified erosion management goals. Specifically, they urge land-use planning, with an emphasis on maintaining natural shorelines. The recommendations encourage new wetland plantings, preservation of preexisting wetland areas, and utilization of beach fill as an alternative to shoreline hardening techniques. They have emphasized, however, that beach fill should only take place in a manner that preserves the natural state of the shoreline. Since SHS are often preferred by local residents, the subcommittee has explicitly recommended sills over other hard shoreline stabilization techniques like rock jetties or bulkheads.
Government and non-government organizations currently encourage the use of soft stabilization methods in low energy estuarine environments. Preferred nonstructural practices center around constructed wetlands, many times in conjunction with rip-rap or sills that assist fragile wetlands in sediment accretion (NCCF). The combination of erosion control strategies and wetland restoration could prove invaluable in protecting both our eroding shorelines and the fragile estuarine ecosystem. By maintaining a significant marsh buffer on a large percent of the waterfront properties in our coastal counties, local residents could alleviate much of the stress from both erosion and stormwater runoff. Many times coastal areas are struggling to adequately deal with stormwater runoff that increases with more impervious surfaces. This leads to results in rapid pulses of water movement through the estuarine system, creating sheer stress along shorelines that amplifies erosion potential (Street et al. 2005). More effective policies could be developed if state stormwater rules were developed simultaneously with shoreline hardening and erosion prevention policies. If landowners are given a clear picture of the importance of marshes in their stormwater buffering capacity as well as erosion protection potential, they would be more apt to favor integrated legislation. Said legislation could help combat what seems to be the positive feedback loop between stormwater runoff, coastal erosion, shoreline hardening, wetland disappearance, and estuarine ecosystem disturbance.
Science in Action
It has been speculated that bulkheads are detrimental to marsh health. However, many unanswered questions remain as to the exact to which bulkheads alter marsh habitats. Many factors influence salt marsh habitats, leading to difficulty in methodologically determining marsh health. Physical factors such as the effects of winds, sedimentation, tides and wave refraction are difficult to quantify. In addition, measuring marsh health using chemical parameters, such as differences between sediment and water column nutrient concentration could give a different indication of health than if examined using biological parameters such as stem counts, chlorophyll a (chl a) concentrations, or organism densities. A thorough examination would incorporate multiple factors that influence marsh health using an assortment of measurement techniques. Unfortunately, such a comprehensive study has not been conducted. Our short study attempted to quantify the biological health of the marsh using metrics such as stem counts, stem heights, chl a, and concentrations of organic matter in marsh sediment cores. Our study also includes suggestions for future research to better improve our understanding of the ramifications of armoring a shoreline.
II. The Effects of Bulkheads on Salt Marsh Habitats Introduction Salt marshes are critical components of the coastal ecosystem and are widely acknowledged as vulnerable to human influence. Shoreline modifications such as bulkheads may alter the natural erosional and depositional processes that help marshes survive and flourish.
Located in the transition zone between marine and terrestrial environments, these areas perform a variety of important functions. Salt marshes provide valuable nursery habitat for a wide range of organisms, including many commercially important fisheries species (Street et al. 2005). Salt marshes act as a buffer for stormwater runoff, thereby reducing the amount of sediments, pollutants, and pathogens introduced into estuarine environments (Mallin 2000). In addition, salt marsh vegetation stabilizes the sediments, encouraging accretion rather than erosion (Brinson et al. 1995).
Rising sea level, storm events, and boat wake all contribute to erosion of coastal and estuarine property. Landowners have attempted to halt this process by installing bulkheads, a common shoreline stabilization method. Estuarine bulkheads are walls built along the shoreline designed to protect and retain sediments above the mean high tide line. Bulkheads shield the shoreline from wave energy by providing a hard surface upon which waves can break. However, they cause wave energy to be redistributed away from the protected property to nearby marshes, unprotected shoreline, and other aquatic habitats North Carolina’s coastal region includes approximately 3,900 miles of estuarine shoreline, and between the years of 1984 and 2000, bulkhead permits were issued for an estimated 11.7% of these shorelines. However, there is no way of knowing how many of these permitted projects were actually completed. Until 2001, bulkheads less than 500 feet in length required no permit or application process. Therefore, the amount of shoreline that has been bulkheaded could be significantly more or less than previously estimated (Street et al. 2005). As development increases, it can be expected that more shoreline hardening structures (SHS) will be utilized in order to protect eroding coastlines (Bozek and Burdick 2005).
Consequently, it is important that we develop a thorough understanding of the impacts of structures, such as bulkheads, on shoreline erosion and the estuarine ecosystems. Many unanswered questions remain as to the influence of bulkheads on salt marsh health. Relatively few studies have examined the effects of bulkheads on the physical and biological processes occurring in salt marshes.