Water: Coastal Zone Act Reauthorization Amendments
Management Measures for Marinas and Recreational Boating - I. Introduction
A. What "Management Measures" Are
This chapter specifies management measures to protect coastal waters from sources of nonpoint pollution from marinas and recreational boating. "Management measures" are defined in section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990 (CZARA) as economically achievable measures to control the addition of pollutants to our coastal waters, which reflect the greatest degree of pollutant reduction achievable through the application of the best available nonpoint pollution control practices, technologies, processes, siting criteria, operating methods, or other alternatives.
These management measures will be incorporated by States into their coastal nonpoint programs, which under CZARA are to provide for the implementation of management measures that are "in conformity" with this guidance. Under CZARA, States are subject to a number of requirements as they develop and implement their coastal nonpoint pollution control programs in conformity with this guidance and will have some flexibility in doing so. The application of these management measures by States to activities causing nonpoint pollution is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA).
B. What "Management Practices" Are
In addition to specifying management measures, this chapter also lists and describes management practices for illustrative purposes only. While State programs are required to specify management measures in conformity with this guidance, State programs need not specify or require the implementation of the particular management practices described in this document. However, as a practical matter, EPA anticipates that the management measures generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices listed in this document have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measures. EPA has also used some of these practices, or appropriate combinations of these practices, as a basis for estimating the effectiveness, costs, and economic impacts of achieving the management measures. (Economic impacts of the management measures are addressed in a separate document entitled Economic Impacts of EPA Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters.)
EPA recognizes that there is often site-specific, regional, and national variability in the selection of appropriate practices, as well as in the design constraints and pollution control effectiveness of practices. The list of practices for each management measure is not all-inclusive and does not preclude States or local agencies from using other technically sound practices. In all cases, however, the practice or set of practices chosen by a State needs to achieve the management measure.
C. Scope of This Chapter
This chapter addresses categories of sources of nonpoint pollution from marinas and recreational boating that affect coastal waters. This chapter specifies 15 management measures grouped under two broad headings: (1) siting and design and (2) operation and maintenance.
Each category of sources is addressed in a separate section of this guidance. Each section contains (1) the management measure(s); (2) an applicability statement that describes, when appropriate, specific activities and locations for which the measure is suitable; (3) a description of the management measure's purpose; (4) the basis for the management measure's selection; (5) information on management practices that are suitable, either alone or in combination with other practices, to achieve the management measure; (6) information on the effectiveness of the management measure and/or of practices to achieve the measure; and (7) information on costs of the measure and/or practices to achieve the measure.
D. Relationship of This Chapter to Other Chapters and to Other EPA Documents
- Chapter 1 of this document contains detailed information on the legislative background for this guidance, the process used by EPA to develop this guidance, and the technical approach used by EPA in this guidance.
- Chapter 7 of this document contains management measures to protect wetlands and riparian areas that serve a nonpoint source abatement function. These measures apply to a broad variety of sources, including marinas and recreational boating sources.
- Chapter 8 of this document contains information on recommended monitoring techniques to (1) ensure proper implementation, operation, and maintenance of the management measures and (2) assess over time the success of the measures in reducing pollution loads and improving water quality.
- EPA has separately published a document entitled Economic Impacts of EPA Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters.
- NOAA and EPA have jointly published guidance entitled Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance. This guidance contains details on how State Coastal Nonpoint Pollution Control Programs are to be developed by States and approved by NOAA and EPA. It includes guidance on the following:
- The basis and process for EPA/NOAA approval of State Coastal Nonpoint Pollution Control Programs;
- How NOAA and EPA expect State programs to provide for the implementation of management measures "in conformity" with this management measures guidance;
- How States may target sources in implementing their Coastal Nonpoint Pollution Control Programs;
- Changes in State coastal boundaries; and
- Requirements concerning how States are to implement their Coastal Nonpoint Pollution Control Programs.
- The basis and process for EPA/NOAA approval of State Coastal Nonpoint Pollution Control Programs;
E. Problem Statement
Marinas and recreational boating are increasingly popular uses of coastal areas. The growth of recreational boating, along with the growth of coastal development in general, has led to a growing awareness of the need to protect waterways. In the Coastal Zone Management Act (CZMA) of 1972, as amended, Congress declared it to be national policy that State coastal management programs provide for public access to the coasts for recreational purposes. Clearly, boating and adjunct activities (e.g., marinas) are an important means of public access. When these facilities are poorly planned or managed, however, they may pose a threat to the health of aquatic systems and may pose other environmental hazards. Ensuring the best possible siting for marinas, as well as the best available design and construction practices and appropriate operation and maintenance practices, can greatly reduce nonpoint source (NPS) pollution from marinas.
Because marinas are located right at the water's edge, there is often no buffering of the release of pollutants to waterways. Adverse environmental impacts may result from the following sources of pollution associated with marinas and recreational boating:
- Poorly flushed waterways where dissolved oxygen deficiencies exist;
- Pollutants discharged from boats;
- Pollutants transported in storm water runoff from parking lots, roofs, and other impervious surfaces;
- The physical alteration or destruction of wetlands and of shellfish and other bottom communities during the construction of marinas, ramps, and related facilities; and
- Pollutants generated from boat maintenance activities on land and in the water.
The management measures described in this chapter are designed to reduce NPS pollution from marinas and recreational boating. Effective implementation will avoid impacts associated with marina siting, prevent the introduction of nonpoint source pollutants, and/or reduce the delivery of pollutants to water resources.
Pollution prevention should be at the fore of any NPS management strategy. It is expected that each coastal State's decision on implementation of these management measures will be based on a management strategy that balances the need for protecting the coastal environment and the need to provide adequate public access to coastal waters.
F. Pollutant Types and Impacts
A marina can have significant impacts on the concentrations of pollutants in the water, sediment, and tissue of organisms within the marina itself. Although sources of pollutants outside the marina are part of the problem, marina design, operation, and location appear to play crucial roles in determining whether local water quality is impacted (NCDEM, 1991).
Marina construction may alter the type of habitat found at the site. Alterations can have both negative and positive effects. For example, a soft-bottom habitat (i.e., habitat characterized by burrowing organisms and deposit feeders) could be replaced with a habitat characterized by fouling organisms attached to the marina pilings and bulkhead. These fouling organisms, however, may attract other organisms, including invertebrates and juvenile fish.
The presence of a marina is not necessarily an indicator of poor water quality. In fact, many marinas have good water quality. Despite this, they may still have degraded biological resources and contaminated sediments resulting from bioaccumulation in organisms and adhesion of pollutants to sediments. A brief summary of some of the impacts that can be associated with marina and boating activities is presented below.
1. Toxicity in the Water Column
Pollutants from marinas can result in toxicity in the water column, both lethal and sublethal, related to decreased levels of dissolved oxygen and elevated levels of metals and petroleum hydrocarbons. These pollutants may enter the water through discharges from boats or other sources, spills, or storm water runoff.
Low Dissolved Oxygen. The organics in sewage discharged from recreational boats require dissolved oxygen (DO) to decompose. The biological oxygen demand (BOD) of a waterbody is a measure of the DO required to decompose sewage and other organic matter (Milliken and Lee, 1990). Accumulation of organic material in sediment will result in a sediment oxygen demand (SOD) that can negatively impact water column DO. The effect of boat sewage on DO can be intensified in temperate regions because the peak boating season coincides with the highest water temperatures and thus the lowest solubilities of oxygen in the water and the highest metabolism rates of aquatic organisms. (As temperature increases, dissolved oxygen levels decrease.) Cardwell and Koons (1981) recorded significant decreases in DO in several northwestern marinas in the late summer and early fall, which are the peak times of marina use. Nixon et al. (1973) measured lower DO levels in an area of marina development than in an adjacent undeveloped bay of similar size. An intensive study in several North Carolina marinas showed significant decreases in DO concentration compared to ambient concentrations in the receiving waterbody. These decreases in DO were thought to result from high SOD within the marinas and poor flushing resulting from improper marina design (NCDEM, 1990).
Metals. Metals and metal-containing compounds have many functions in boat operation, maintenance, and repair. Lead is used as a fuel additive and ballast and may be released through incomplete fuel combustion and boat bilge discharges (NCDEM, 1991). Arsenic is used in paint pigments, pesticides, and wood preservatives. Zinc anodes are used to deter corrosion of metal hulls and engine parts. Copper and tin are used as biocides in antifoulant paints. Other metals (iron, chrome, etc.) are used in the construction of marinas and boats.
Many of these metals/compounds are found in marina waters at levels that are toxic to aquatic organisms. Copper is the most common metal found at toxic concentrations in marina waters (NCDEM, 1990, 1991). Dissolved copper was detected at toxic concentrations at several marinas within the Chesapeake Bay (Hall et al., 1987). The input of copper via bottom paints and scrapings has been shown to be quite significant (Young et al., 1974). Tin in the form of butyltin, an extremely potent biocide, has been detected at toxic levels within marina waters nationwide (Stephenson et al., 1986; Maguire, 1986; Grovhoug et al., 1986; Stallard et al., 1987). The use of butyltins in bottom paint is now regulated, and butyltins cannot be used on nonaluminum recreational boats under 25 meters in length. High levels of zinc, chromium, and lead were also detected in waters within North Carolina marinas (NCDEM, 1990). Table 5-1 presents results of a recent study of boatyard hull pressure-washing wastewater in the Puget Sound area that revealed concentrations of metals and other pollutants that are of concern to environmental regulators (METRO, 1992a).
Petroleum Hydrocarbons. McMahon (1989) found elevated concentrations of hydrocarbons in marina waters and attributed them to refueling activities and bilge or fuel discharge from nearby boats.
2. Increased Pollutant Levels in Aquatic Organisms
Aquatic organisms can concentrate pollutants in the water column through biological activity. Copper and zinc concentrations in oysters were significantly higher in oysters in South Carolina and North Carolina marinas than at reference sites (NCDEM, 1991; SCDHEC, 1987). Increased levels of copper, cadmium, chromium, lead, tin, zinc, and PCBs were found in mussels from southern California marina waters (CARWQCB, 1989; Young et al., 1979). Three months after planting, concentrations of lead, zinc, and copper in oysters transplanted to several Australian marinas were two to three times higher than those of control sites (McMahon, 1989). Concentrations of copper in a green algae and the fouling community were significantly higher in a Rhode Island marina area than in adjacent control areas (Nixon et al., 1973). Several polynuclear aromatic hydrocarbons were detected in oyster tissue at marinas in South Carolina (Marcus and Stokes, 1985; Wendt et al., 1990).
3. Increased Pollutant Levels in Sediments
Many of the contaminants found in the storm water runoff of marinas do not dissolve well in water and accumulate to higher concentrations in sediments than in the overlying water. Contaminated sediments may, in turn, act as a source from which these contaminants can be released into the overlying waters. Benthic organisms those organisms that live on the bottom or in the sediment are exposed to pollutants that accumulate in the sediments and may be affected by this exposure or may avoid the contaminated area.
Metals. Copper is the major contaminant of concern because most common antifouling paint preparations contain cuprous oxide as the active biocide component (METRO, 1992a). In most cases metals have a higher affinity for sediments than for the water column and therefore tend to concentrate there. A recent Puget Sound area study of wastewater from boat hull pressure washing found that suspended solids accounted for 96 percent of the copper, 94 percent of the lead, and 83 percent of the zinc in the wastewater (see Table 5-1 for concentrations). Most of the metal concentrations were associated with particles less than 60 microns in size, resulting in their settling out of solution slowly (METRO, 1992a). Stallard et al. (1987) noted that the sediments of nearly every California marina tested had high concentration of butyltins. Marina sites in North Carolina had significantly higher levels of arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc than did reference sites (NCDEM, 1991). McMahon (1989) found significantly higher concentrations of copper, lead, zinc, and mercury in the sediments at a marina site than in the parent waterbody. Within the marina, higher levels of copper and lead were found near a maintenance area drain and fuel dock, suggesting the drain as a source of copper and lead and the fuel dock as a possible source of lead. Sediments at most stations within Marina Del Rey were sufficiently contaminated with copper, lead, mercury, and zinc to affect fish and/or invertebrates, especially at the larval or juvenile stage (Soule et al., 1991). Researchers thought that this contamination might account for the absence of more sensitive species and the low diversity within the marina. However, the extent of the sediment contamination resulting from marina-related activities was unclear.
Petroleum Hydrocarbons. Petroleum hydrocarbons, particularly polynuclear aromatic hydrocarbons (PAHs), tend to adsorb to particulate matter and become incorporated into sediments. They may persist for years, resulting in exposure to benthic organisms. Voudrias and Smith (1986) reported that sediments from two Virginia creeks with marinas contained significantly higher levels of hydrocarbons than did control sites. The North Carolina Division of Environmental Management (NCDEM, 1990) found PAHs in the sediments of six marinas, all of which had fuel docks. Nearby reference areas did not appear to be affected. Marcus et al. (1988) found an increase in PAHs in the sediments of two South Carolina marinas. Sources of petroleum hydrocarbons were identified as the origin of sediment contamination within several Australian marinas; however, a well-flushed marina in this study did not have an increase in sediment hydrocarbons (McMahon, 1989). This finding supports the supposition that sufficient flushing within a marina basin prevents build-up of pollutants in marina sediments.
4. Increased Levels of Pathogen Indicators
Studies conducted in Puget Sound, Long Island Sound, Narragansett Bay, North Carolina, and Chesapeake Bay have shown that boats can be a significant source of fecal coliform bacteria in areas with high boat densities and low hydrologic flushing (NCDEM, 1990; Sawyer and Golding, 1990; Milliken and Lee, 1990; Gaines and Solow, 1990; Seabloom et al., 1989; Fisher et al., 1987). Fecal coliform levels in marinas and mooring fields become elevated near boats during periods of high boat occupancy and usage. NOAA identified boating activities (the presence of marinas, shipping lanes, or intracoastal waterways) as a contributing source in the closure to harvesting of millions of acres of shellfish-growing waters on the east coast of the United States (Leonard et al., 1989).
5. Disruption of Sediment and Habitat
Boat operation and dredging can destroy habitat; resuspend bottom sediment (resulting in the reintroduction of toxic substances into the water column); and increase turbidity, which affects the photosynthetic activity of algae and estuarine vegetation. Paulson and Da Costa (1991) demonstrated that propeller-induced flows can contribute significantly to bottom scour in shallow embayments and may have adverse effects on water clarity and quality. The British Waterways Board (1983) noted that propeller-driven boats may impact the aquatic environment and result in bank erosion. Waterways with shallow water environments would be affected as follows:
- The propeller would cut off or uproot water plants growing up from the bottom, and
- The propeller agitation of the water (propwash) would disturb the sediments, creating turbidity that would reduce the light available for photosynthesis of plants, impact feeding and clog the breathing mechanisms of aquatic animals, and smother animals and plants.
EPA (1974) noted a resuspension of solids from the bottom and disturbance to aquatic macrophytes following boating activity. Changes in turbidity were dependent on water depth, motor power, operational time and type, and nature of sediment deposits. The increase in turbidity was generally accompanied by an increase in organic carbon and phosphorus concentrations. However, the possible contribution of these nutrients to eutrophication was not determined. The biological communities of rivers may be impacted by boat traffic, which can increase turbidity; resuspend sediments that move into backwaters; create changes in waves, velocity, and pressure; and increase shoreline erosion (USFWS, 1982).
Dredging may alter the marina and the adjacent water by increasing turbidity, reducing the oxygen content of the water, burying benthic organisms, causing disruption and removal of bottom habitat, creating stagnant areas, and altering water circulation (Chmura and Ross, 1978). Some of these impacts (e.g., turbidity and reduced DO) are temporary and without long-term adverse effects. Dredging is addressed under CWA section 404 and associated regulations and is therefore not discussed further in this chapter.
6. Shoaling and Shoreline Erosion
Shoaling and shoreline erosion result from the physical transport of sediment due to waves and/or currents. These waves and currents may be natural (wind-induced, rainfall runoff, etc.) or human-induced (alterations in current regimes, boat wakes, etc.).
The British Waterways Board (1983) noted that when vessel-generated waves reach the shallow margins of a waterway, they can erode the banks and the bed, tending to wash away fringing plants and their associated animal life. The Waterways Board also found that a substantial volume of the sediment that results in shoaling comes from bank erosion and that removal of this material by dredging is a costly recurrent expense, especially where boat traffic causes extensive bank erosion. Factors influencing vessel-generated shoreline erosion include the distance of the boat from shore, boat speed, side slopes, sediment type, and depth of the waterway (Camfield et al., 1980; Sorensen, 1986; Zabawa and Ostrom, 1980).
G. Other Federal and State Marina and Boating Programs
1. NPDES Storm Water Program
The storm water permit program is a two-phase program enacted by Congress in 1987 under section 402(p) of the Clean Water Act. Under Phase I, National Pollutant Discharge Elimination System (NPDES) permits are required to be issued for municipal separate storm sewers serving large or medium-sized populations (greater than 250,000 or 100,000 people, respectively), and for storm water discharges associated with industrial activity such as certain types of marinas. Permits are also to be issued, on a case-by-case basis, if EPA or a State determines that a storm water discharge contributes to a violation of a water quality standard or is a significant contributor of pollutants to waters of the United States. EPA published a rule implementing Phase I on November 16, 1990.
a. Which marinas are regulated by the NPDES Storm Water Program?
Under the NPDES Storm Water Program, discharge permits are required for point source discharges of storm water from certain types of marinas. A point source discharge of storm water is a flow of rainfall runoff in some kind of discrete conveyance (a pipe, ditch, channel, swale, etc.).
If a marina is primarily in the business of renting boat slips, storing boats, cleaning boats, and repairing boats, and generally performs a range of other marine services, it is classified under the storm water program (using the Standard Industrial Classification (SIC) system developed by the Office of Management and Budget) as a SIC 4493. Marinas classified as SIC 4493 are the type that may be regulated under the storm water program and may be required to obtain a storm water discharge permit.
A marina that is classified as a SIC 4493 is required to obtain an NPDES storm water discharge permit if vehicle maintenance activities such as vehicle (boat) rehabilitation, mechanical repairs, painting, fueling, and lubrication or equipment cleaning operations are conducted at the marina. The storm water permit will apply only to the point source discharges of storm water from the maintenance areas at the marinas. Operators of these types of marinas should consult the water pollution control agency of the State in which the marina is located to determine how to obtain a storm water discharge permit.
b. Which marinas are not regulated by the NPDES Storm Water Program?
Marinas classified as SIC 4493 that are not involved in equipment cleaning or vehicle maintenance activities are not covered under the storm water program. Likewise, a marina, regardless of its classification and the types of activities conducted, that has no point source discharges of storm water, is also not regulated under the NPDES storm water program. In addition, some marinas are classified SIC code 5541 - marine service stations and are also not regulated under the NPDES Storm Water Program. These types of marinas are primarily in the business of selling fuel without vehicle maintenance or equipment cleaning operations.
c. What marina activities are covered by this guidance?
EPA has not yet promulgated regulations that would designate additional storm water discharges, beyond those regulated in Phase I, that will be required to be regulated in Phase II. Therefore, marina discharges that are not covered under Phase I, including those discharges that potentially may be ultimately covered by Phase II of the storm water permits program, are covered by this management measures guidance and will be addressed by the Coastal Nonpoint Pollution Control Programs. Any storm water discharge at a marina that ultimately is issued an NPDES permit will become exempt from this guidance and from the Coastal Nonpoint Pollution Control Program at the time that the permit is issued.
2. Other Regulatory Programs
The management measures for marinas do not address discharge of sanitary waste from vessels. They do, however, specify a measure to require that new marinas be designed to include pumpout stations and other facilities to handle sanitary waste from marine toilets, also referred to as marine sanitation devices (MSDs), and another measure to ensure that these facilities are properly maintained.
Vessels are not required to be equipped with an MSD. If a boat does have an MSD, however, the MSD has to meet certain standards set by EPA as required by CWA section 312. In addition to EPA standards for MSDs, EPA may allow a State to prohibit all discharges (treated or untreated) from MSDs, thus declaring the area a "no-discharge zone." Any State may apply to the EPA Administrator for designation of a "no-discharge zone" in some or all of the waters of the State; however, EPA must ensure that these waters meet certain tests before granting the application.
The siting and permitting process to which marinas are subject varies from State to State. State and Federal agencies both play a role in this process. Under section 10 of the Rivers and Harbors Act of 1899, the U.S. Army Corps of Engineers (USACE) regulates all work and structures in navigable waters of the United States. Under section 404 of the Clean Water Act, USACE permits are issued or denied to regulate discharges of dredged or fill materials in navigable waters of the United States, including wetlands.
All coastal States with Federally-approved coastal zone management programs can review Federal permit applications, and some States regulate dredge and fill, marshlands, or wetlands permitting for marina development. All States with Federally-approved coastal programs have the authority to object to section 10/section 404 permits if the proposed action is inconsistent with the State's coastal zone management program. Some States require permits for the use of State water bottomlands. States have authority under the Clean Water Act to issue section 401 water quality certifications for Federally-permitted actions as part of their water quality standards program.
The Food and Drug Administration (FDA) has established fecal coliform standards for certified shellfish-growing waters. Each coastal State regulates its own shellfish sanitation program under the National Shellfish Sanitation Program. States must participate if they wish to export shellfish across State lines. Various approaches are used to comply.
Some States also have a State coastal zone management permit providing them authority over development activities in areas located within their defined coastal zone. Alternatively, or in addition to this permitting authority, some States have regulatory planning authority in given areas of the coast, allowing them to influence the siting of marinas, if not their actual design and construction.
Finally, Massachusetts has developed a Harbor Planning Program, and other States (e.g., Connecticut, Rhode Island, New York, and Oregon) are developing similar programs. Municipalities participating in the program develop Harbor Management Plans. The plans must be consistent with approved coastal zone management plans, and they offer benefits such as giving municipalities greater influence over licensing of State tidelands and priority consideration for grants. The plans recommend comprehensive, long-term management programs that help municipalities balance conservation and development, address pollution impacts on a cumulative rather than piecemeal basis, and resolve conflicts over water-dependent and non-water-dependent uses of the waterfront.
H. Applicability of Management Measures
The management measures in this chapter are intended to be applied by States to control impacts to water quality and habitat from marina siting, construction (both new and expanding marinas), and operation and maintenance, as well as boat operation and maintenance. Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint source (NPS) programs in conformity with the management measures and will have some flexibility in doing so. The application of these management measures by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance.
The management measures for marinas are applicable to the facilities and their associated shore-based services that support recreational boats and boats for hire. The following operations/facilities are covered by the management measures of this chapter:
- Any facility that contains 10 or more slips, piers where 10 or more boats may tie up, or any facility where a boat for hire is docked;
- Boat maintenance or repair yards that are adjacent to the water;
- Any Federal, State, or local facility that involves recreational boat maintenance or repair that is on or adjacent to the water;
- Public or commercial boat ramps;
- Any residential or planned community marina with 10 or more slips; and
- Any mooring field where 10 or more boats are moored.
Many States already use a 5- to 10-slip definition for marinas. The 10-slip definition for marinas is also based on Federal legislation that implements MARPOL (the International Convention for the Prevention of Pollution from Ships). This legislation requires adequate waste disposal facilities for ships at facilities with 10 or more slips. This guidance is not intended to address shipyards where extensive repair and maintenance of larger vessels occur. Such facilities are subject to NPDES point source and storm water permitting requirements.
Certain types of changes or additions to existing marinas may produce insignificant differences in impacts from such marinas, while other types of changes and expansions may have a far greater effect. Activities that alter the design, capacity, purpose, or use of the marina are subject to the siting and design management measures. The States are to define: (1) activities that significantly change the physical configuration or construction of the marina, (2) activities that significantly change the number of vessels accommodated, or (3) the operational changes that significantly change the potential impacts of the marina. Potential changes to marinas may be treated in the same manner as new marinas; i.e., the changes to the marina would be subject to applicable siting and design management measures.
The management measures for siting and design are applicable to new marinas. Application of the management measures to expanding marinas should be done on a case-by-case basis and should hinge on the potential for the expansion to impact water quality and important habitat. For example, an expanding marina would not be required to implement the flushing, water quality assessment, or shoreline stabilization management measures if the expansion involved only an increase in the number of parking spaces. The storm water runoff management measure is the only siting and design measure that is always applicable to existing and expanding marinas, as well as new marinas.
One method that has been used successfully by several States to determine whether an alteration/expansion is significant is to set a marina perimeter when the marina is constructed. Thereafter, alterations that occur within that perimeter (such as dock reconfiguration) are considered not significant. Another method that States have used is to set a limit, such as a 25 percent increase in the number of slips or a set number of slips (e.g., an increase of more than five slips is considered significant). Rhode Island has successfully implemented a combination of these methods (Rhode Island Coastal Resources Management Program, Section 300.4).
Changes to a marina may also result from catastrophic natural disasters such as hurricanes and severe flooding. It is possible, in smaller marinas, that efforts to rebuild need not be subject to all siting and design management measures.