COAST Defined

Section I: Coastal County Aggregations Used in STICS

Many social science data sets are collected and commonly reported using political boundaries, especially counties. As a result, “coastal counties” has emerged as common and readily recognizable framework to describe the human dimension of the coast. NOAA references two different coastal county suites for reporting demographic and economic information. The first county suite is the Coastal Watershed Counties, where land use and water quality changes most directly impact coastal ecosystems. The permanent U.S. population that resides in the Coastal Watershed counties can be thought of as "the population that most directly affects the coast." The second county suite is the Coastal Shoreline Counties, those counties that are directly adjacent to the open ocean, major estuaries, and the Great Lakes, and which due to their proximity to these waters, bear a great proportion of the full range of effects from coastal hazards (not just coastal inundation) and host the majority of economic production associated with coastal and ocean resources. The permanent U.S. population that resides in the Coastal Shoreline Counties can be thought of as "the population most directly affected by the coast." Both the Coastal Watershed Counties and the Coastal Shoreline Counties are based on 2010 county boundaries. For more detailed information on this model see The "Coast" is Complicated: A Model to Consistently Describe the Nation's Coastal Population associated peer-reviewed journal article.

A. Coastal Watershed Counties

The U.S. Population that most directly affects the coast resides in a standard suite of Coastal Watershed Counties where land use and water quality changes most directly impact coastal ecosystems. NOAA developed a list of coastal counties based on NOAA coastal watersheds and USGS coastal cataloging units as delineated in the NOAA Coastal Assessment Framework (CAF). This methodology emphasizes land areas within which water flows into the ocean or Great Lakes, and provides a broader, coastal watershed focus to the delineation coastal counties. Through this methodology, a county is considered a Coastal Watershed County if one of the following criteria is met: (1) at a minimum, 15 percent of the county’s total land area is located within a coastal watershed or (2) a portion of or an entire county accounts for at least 15 percent of a coastal USGS 8-digit cataloging unit. The 15-percent rule was selected as an appropriate level for capturing counties with a significant impact on coastal and ocean resources.

There are a few exceptions to these rules. Cook and Lake Counties in Illinois, as examples, do not meet the 15 percent rule for a coastal watershed or a coastal cataloging unit. However, they directly border Lake Michigan, so they are included in the suite of coastal watershed counties. There are three other instances where single counties were designated as noncoastal because they did not meet the "15% critieria", but they are completely surrounded by coastal watershed counties that do meet the "15% criteria". In these three instances - Allan Parish, LA, Highlands, FL and Greene, NC - these counties were included in NOAA's coastal watershed county suite. In addition, NOAA does not include Alaska or Hawaii in its Coastal Assessment Framework. However, all counties (boroughs and census areas in Alaska) where the shoreline of the 2010 Census County Boundary intersects with a cataloging unit, it is considered coastal. As a result, all five of Hawaii’s counties, and 25 of Alaska’s , are included in NOAA’s suite of coastal watershed counties.

For additional explanation about this methodology, click here.

Click here to download this list in ASCII tab-delimited format (2010 based).
Click here to download this geography in a shapefile format (2010 based)

B. Coastal Shoreline Counties

The U.S. population most directly affected by the coast resides in a standard suite of Coastal Shoreline Counties that are directly adjacent to the open ocean, major estuaries, and the Great Lakes, which due to their proximity to these waters, bear a great proportion of the full range of effects from coastal hazards and host the majority of economic production associated with coastal and ocean resources. The Federal Emergency Management Agency (FEMA) has defined a coastal county as one that: (1) has a coastline bordering the open ocean or Great Lakes coasts (or associated sheltered water bodies), or (2) contains velocity zones (V-zones) or coastal high hazard areas. V-zones are areas where wave heights more than 3 feet and/or high velocity water can cause structural damage in a 100-year flood, a flood with a 1-percent chance of occurring or being exceeded in a given year.

Click here to download this list in ASCII tab-delimited format (2010 based).
Click here to download this geography in a shapefile format (2010 based)

Summary of Coastal Counties (Year 2010)

  Coastal Watershed
Counties
Coastal Shoreline
Counties
Coastal States All Great
Lakes
All Great
Lakes
NOTE:
  • The districts found within the American Samoa are the US Census Bureau county equivalents.
  • The municipalities found within the Commonwealth Northern Mariana Islands (CNMI)
    are the U.S. Census Bureau county equivalents.
  • The "municipios" found within Puerto Rico are the US Census Bureau county equivalents.
Alaska
25   25  
Alabama
8   2  
California
29   20  
Connecticut
8   4  
Delaware
3   3  
District of Columbia
1   1  
Florida
62   38  
Georgia
28   9  
Hawaii
5   5  
Illinois
2 2 2 2
Indiana
9 9 3 3
Louisiana
39   21  
Massachusetts
12   9  
Maryland
20   18  
Maine
14   8  
Michigan
74 74 41 41
Minnesota
4 4 3 3
Mississippi
12   3  
New Hampshire
6   2  
New Jersey
20   15  
New York
39 21 22 9
North Carolina
38   22  
Ohio
24 24 8 8
Oregon
12   7  
Pennsylvania
13 1 3 1
Rhode Island
5   5  
South Carolina
22   9  
Texas
41   18  
Virginia
61   40  
Washington
19   15  
Wisconsin
23 23 15 15
Sub-Total 678 158 396 82
Territories      
American Samoa
5 3
Guam
1 1
Northern Mariana Islands
4 4
Puerto Rico
78 45
US Virgin Islands
3 3
Sub-Total 91 56
TOTAL 769 158 452 82

Section II: Coastal Management Jurisdictions Used in STICS

This section provides a more detailed description of each coastal management jurisdiction used in STICS, including example maps and links to downloadable boundary files. All downloadable boundaries offered below can be linked to socioeconomic data tables using the Data Query and Download Tool.

A. Place-Based Management Programs

1. NOAA National Estuarine Research Reserve System Target Watersheds

The National Estuarine Research Reserve System (NERRS) is a network of 28 reserves dedicated to long-term research, monitoring, education and resource stewardship. For 23 NERRS units an associated target watershed has been delineated, which is the watershed area that most directly impacts reserve habitats. The remaining five NERRS units do not have a target watershed; they are: Kachemak Bay, Mission Aransas, Narragansett Bay, Waquoit Bay, and Lake Superior. The geography was provided by NERRS.

2. NOAA National Estuarine Research Reserve System Large Estuarine Watersheds

For each of the 28 National Estuarine Research Reserve System ( NERRS) units and their target watersheds (where applicable), large estuarine watersheds have been delineated using a flow analysis based on a 30-meter digital elevation model corresponding most closely to the boundaries of USGS 8-digit Hydrologic Unit Code (HUC) watersheds. The geography was provided by NERRS.

3. U.S. EPA National Estuary Program Study Areas

The mission of the National Estuary Program (NEP) is to protect and restore America’s nationally significant estuaries, and currently has 28 program units. Each NEP has a designated study area and develops and implements a Comprehensive Conservation and Management Plan for that area. All 28 NEPs have a single study area, with the exception of the Puget Sound NEP, which has divided its study area into seven sub-systems.The geography was provided by NEP.

4. U.S. EPA National Estuary Program Watersheds

The National Estuary Program (NEP) has identified the estuarine and fluvial drainage areas associated with each of their 28 program unit study areas. These larger watersheds were delineated so the NEPs can better understand pressures created upstream of their study areas, providing critical information to successfully implement their Comprehensive Conservation and Management Plans. The geography was provided by NEP.

5. U.S. EPA Council of Large Aquatic Ecosystems (LAE) Watersheds

The Council of Large Aquatic Ecosystems is composed of ten geographically based, large aquatic ecossystem programs across the U.S. Ecosystem-based programs complement national programs, such as the discharge permit program or infrastructure financing program, by delivering plans and programs tailored to a specific, critical aquatic ecosystem. The Council seeks to strengthen these ecosystem programs by facilitating communication among the LAE members and their national water program counterparts. The geography was provided by EPA.

6. Coastal Zone Management Act (CZMA) State Coastal Zone Boundaries

Authority for the delineation of state coastal zones is established under section 304 of the Coastal Zone Management Act (CZMA), which states:

The zone extends inland from the shorelines only to the extent necessary to control shorelands, the uses of which have a direct and significant impact on the coastal waters, and to control those geographical areas which are likely to be affected by or vulnerable to sea level rise.

This definition provided no national guidance, and therefore, the states took many different approaches to establish their coastal zones. For example, four states have their total land area within the coastal zone: Rhode Island, Delaware, Florida, and Hawaii. Other states, such as Washington and South Carolina, use county boundaries to delineate their coastal zone boundary. For a complete description of the methods used by each state with a Coastal Zone Management Program see the coastal zone definition for each state. The geography was provided by the CZ Management Program.

Coastal Zone Management Act (CZMA) State Coastal Zone-Based Coastal Counties

A county is considered a coastal zone county if it is included within or intersects a Coastal Zone Management Act (CZMA) state coastal zone boundary.

The U.S. Coastal Zone boundary file provided on the STICS Web site (link below) excludes several states including Alaska, Hawaii, Michigan, Indiana, Illinois, as well as the U.S. Territories.  To determine which counties fall within or are partially within a state’s coastal zone, several methods were employed. 

  • First, using a GIS, the U.S. Coastal Zone boundary file was intersected with U.S. Counties boundary file resulting in a list of counties whose area partially or completely falls within the coastal zone.  Counties whose boundary is used as the inland extent of the coastal zone were excluded. 
  • Second, counties that  weren’t included in the U.S. Coastal Zone boundary file were examined on a case by case basis resulting in the following:
    • Michigan - Coastal zone counties within Michigan are listed on the Michigan Department of Recreation and the Environment (http://www.michigan.gov/deq/0,1607,7-135-3313_3677_3696-90802--,00.html). 
    • Illinois - Coastal zone counties are discussed on the Illinois Department of Natural Resources (http://dnr.state.il.us/cmp/).
    • Alaska and Puerto Rico – Detailed descriptions of the coastal zones within Puerto Rico and Alaska are not readily available.  Consequently, counties that intersect their coastal zone are difficult to determine.  For the purposes of this list, coastal zone counties for Puerto Rico and Alaska have been selected based on their intersection with the outer boundary of the Census2000 state boundary files. 
    • Remaining States and Territories - were selected based on the descriptions provided in the downloadable .PDF file provided on this page. 

Coastal zone boundaries and the counties that intersect these boundaries are subject to change.  The table below will be updated if such changes should occur. Click here to download this list in ASCII tab-delimited format (2010 based).

 

7. NOAA's National Marine Sanctuaries (NMS) Counties

The mission of NOAA's National Marine Sanctuaries is to serve as the trustee for the nation's system of marine protected areas, to conserve, protect, and enhance their biodiversity, ecological integrity and cultural legacy. For more information about the Program's history, and the creation of the marine sanctuaries, click here.

A list of counties associated to each of the National Marine Sanctuaries has been obtained by the NMS science staff to assess natural and human-caused environmental changes within the sanctuaries and to assist sanctuary scientists pursue the best possible science and involve stakeholders in determining goals and objectives of social science projects.

B. Floodplains

FEMA 100-Year Coastal Flood Hazard Areas (CFHA) and Special Flood Hazard Areas [SFHA (Coastal + Riverine)]

These are areas subject to one-percent annual chance (100-year) coastal floods as determined by the Federal Emergency Management Agency (FEMA) through the National Flood Insurance Program (NFIP). FEMA defines areas subject to one-percent annual chance floods as Special Flood Hazard Areas (SFHAs).  These areas are also informally known as 100-year flood hazard areas.  FEMA delineates and maps two types of SFHAs: AE Zones and VE Zones.  In general, AE Zones are areas subject to either a one-percent annual chance riverine flood, or a one-percent annual chance coastal flood that does not have high velocity waters or damaging wave action associated with the flood.  VE Zones are almost always coastal (includes Great Lakes coastal areas) SFHAs. Note that NFIP floodplain management regulations must be enforced, and mandatory purchase of flood insurance may be required, in all SFHAs. VE Zones are differentiated from AE Zones (coastal or riverine) because not only are VE Zones subject to flood damage, but they are also subject to damages resulting from high velocity waters or wave action associated with coastal flooding.

Coastal areas defined by VE Zones, or by AE Zones associated with coastal flooding, may collectively be referred to as Coastal Special Flood Hazard Areas (or more informally as 100-Year Coastal Flood Hazard Areas (CFHA)).  FEMA does not officially map boundary lines that separate AE Zones associated with coastal flooding from AE Zones associated with riverine flooding.  FEMA intersected the CFHA boundaries (coastal flooding) with counties creating the FEMA's coastal county list mentioned in STICS. AECOM a contractor for FEMA provided the regional geodatabases of the FEMA floodplain boundaries. The STICS team in partnership with NOAA's Coastal Services Center (CSC) obtained the 100-yr FEMA SFHA geography by using the appropriate "FEMA Flood Zones" from the regional databases.

STICS includes the SWEL-sourced polygons that have been peer reviewed and developed by FEMA with the purpose of obtaining population estimates where there is no NFHL nor Q3 coverage such as along the Great Lakes and Alaskan coastlines. Coastal A Zone boundaries were approximated by associating a 1% annual chance still-water elevation to the DEM. Still-water elevations were obtained by referencing published FEMA flood insurance study reports and selecting a representatitve 1% annual chance still-water elevation for each coastal county without NFHL or Q3 data. A polygon coastal A Zone area was then approximated by identifying grid cells from the DEM below the representative still-water elevation. More information about this method can be accessed from: http://www.floods.org/PDF/JCR_Est_US_Pop_100y_CFHA_2010.pdf

FEMA Disclaimer:

"In 2007 and 2008, FEMA conducted a coastal demographics study in which a boundary line was estimated that separates AE Zones associated with riverine flooding from AE Zones associated with coastal flooding.  These “unofficial” coastal AE Zone boundaries were combined with official VE Zone boundaries in order to estimate the spatial ground limits of all areas subject to the one-percent annual chance flood (i.e., 100-year Coastal Flood Hazard Areas).  The boundaries used to establish the 100-year Coastal Flood Hazard Areas are the product of a planning-level study conducted by FEMA using readily available datasets. Due to the nation-wide scale of the study and the relatively coarse spatial accuracy of the available data used, it is recommended that the 100-year Coastal Flood Hazard Area boundaries be used only for planning-level studies such as national or regional coastal demographic studies. It is important to emphasize that the boundary line separating AE Zones associated with riverine flooding, from AE Zones associated with coastal flooding, has not been adopted by FEMA and is not intended to be used for floodplain management or insurance purposes under the NFIP."

C. Watersheds

1. NOAA’s Coastal Assessment Framework (CAF)

NOAA’s Coastal Assessment Framework (CAF) provides a comprehensive national framework of coastal watersheds that facilitates characterization of entire watersheds in the U.S., both coastal and upstream portions, with a nested hierarchy of spatial units for the small and large coastal resource data analyses needed to effectively manage our nation's diverse coastal areas. For Alaska and Hawaii, it includes coastal USGS-8-digit Cataloging Units.

The CAF is composed of:

An Estuarine Drainage Area (EDA) is defined as that part of an estuary’s entire watershed that empties directly into the estuary and includes the downstream-most USGS cataloging unit in which the head of tide is found. EDAs may be composed of all or part of a single or several USGS hydrologic units and include all or part of the USGS cataloging unit containing the most upstream extent of tidal infl uence (head-of-tide).

A Coastal Drainage Area (CDA) is defined as that component of an entire watershed that meets these three criteria: 1) it is not part of any one of the 102 EDAs; 2) it drains directly into an ocean, an estuary, or the Great Lakes; and 3) it contains the downstream-most cataloging unit in which the head of tide is found (in the Great Lakes, tide refers to meteorologically created tides).

A Fluvial Estuarine Drainage Area (FEDA) is that component of an estuary’s entire watershed upstream of the EDA boundary. FEDAs have land components only. The huge 1,131,700 square mile Mississippi River FDA dwarfs all others, and makes up over half of the total drainage area covered by the entire CAF.

A Fluvial Coastal Drainage Area (FCDA) is that component of a coastal watershed that lies “upstream” of the CDA boundary. Like FDAs, FCDAs only have a land component.

2. USGS Hydrologic Units: Cataloging Units, Accounting Units, Sub-regions, and Regions

USGS has developed a national framework of drainage basin boundaries where the U.S. is divided and sub-divided into successively smaller hydrologic units. These hydrologic units are classified into four levels: regions (2-digits, average size: 177,560 sq mi), sub-regions (4-digits, average size: 16,800 sq mi), accounting units (6-digits, average size: 10,596 sq mi), and cataloging units (8-digits, average size: 703 sq mi) (http://water.usgs.gov/GIS/huc.html). These hydrologic units are arranged within each other, from the smallest (cataloging units) to the largest (regions). The first level of classification divides the Nation into 21 major geographic regions. The second level of classification divides the 21 regions into 221 sub-regions. The third level of classification subdivides many of the sub-regions into 378 accounting units. The fourth level of classification is the Hydrologic Cataloging Unit (HUC), the smallest element in the hierarchy of hydrologic units. There are 2,264 8-digit HUCs in the Nation. Efforts are underway to add further 5th and 6th level subdivisions (http://www.ncgc.nrcs.usda.gov/products/datasets/watershed/).

Using this framework, NOAA has defined a coastal cataloging unit as a USGS 8-digit HUC that falls entirely within or straddles an EDA or CDA. Using this definition, coastal HUCs are basically those USGS 8-digit HUCs that are adjacent to the shoreline.

D. Political

The U.S. Census Bureau provides data for a range of geographic types from the United States down to a Census Block. A detailed description of Census geography terminology can be obtained from the U.S. Census Bureau web site (American Factfinder - http://factfinder.census.gov/home/en/epss/glossary_a.html).

U.S. Census Regions, Divisions, States, Counties, Places, Voting Districts, Zip Code Tabulation Areas, Block Groups, and Blocks

The U.S. Census Bureau has identified four Census Regions (Northeast, Midwest, South, and West) within the United States, and further organizes them into nine Divisions. Regions and Division are grouping of states which are further subdivided by counties or equivalent entities.

A U.S. state is any one of 50 federated states of the United States of America that share sovereignty with the federal government. Four states (Kentucky, Massachusetts, Pennsylvania, and Virginia) use the official title of commonwealth rather than state. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. STICS provides socioeconomic data aggregated to States.

Counties are the primary legal subdivision of most states. In Louisiana, these subdivisions are known as parishes. In Alaska, which has no counties, the county equivalents are boroughs, a legal subdivision, and census areas, a statistical subdivision. In four states (Maryland, Missouri, Nevada and Virginia), there are one or more cities that are independent of any county and thus constitute primary subdivisions of their states. The District of Columbia has no primary divisions, and the entire area is considered equivalent to a county for statistical purposes. In Puerto Rico, municipios are treated as county equivalents. STICS provides socioeconomic data aggregated to Counties and also defines Coastal Watershed Counties and Coastal Shoreline Counties.

Places are concentrations of population either legally bounded as an incorporated place, or identified as a Census Designated Place (CDP) including “comunidades” and “zonas urbanas” in Puerto Rico. Incorporated places have legal descriptions of borough (except in Alaska and New York), city, town (except in New England, New York, and Wisconsin), or village. Incorporated places recognized in decennial US census data products are those reported to the U.S. Census Bureau as legally in existence on January 1, 2000, under the laws of their respective states, as cities, boroughs, towns, and villages. Demographic data for Places are derived from Blocks data.

Voting district (VTD) is a generic term adopted by the Bureau of the Census to include the wide variety of small polling areas, such as election districts, precincts, , legislative districts, or wards, that State and local governments create for the purpose of administering elections. Some States also use groupings of these entities to define their State and local legislative districts, as well as the districts they define for election of members to the U.S. House of Representatives. Demographic data for VTDs are derived from Blocks data.

Zip Code Tabulation Areas (ZCTA) are geographic areas that approximate the delivery area for a five-digit or a three-digit ZIP Code. ZCTAs do not precisely depict the area within which mail deliveries associated with that ZIP Code occur. Demographic data for ZCTAs are derived from Blocks data.

Block Groups are subdivisions of census tracts (or, prior to 2000, block numbering areas). A block group is the smallest geographic unit for which the Census Bureau tabulates sample data. A Block Group is a cluster of blocks and its average size is approximately 452 housing units of 1,100 people. STICS provides demographic data by Census Block Groups.

Blocks are the smallest geographic units for which the Census Bureau tabulates 100-percent data. Blocks are small areas bounded on all sides by both visible features such as streets, roads and streams, and invisible boundaries such as city, town, property lines and others.

For more information see the Standard Hierarchy of Census Geographies Entities.

 

E. Other

1. 50 Mile Fixed-Distance Inland Boundary

The area within a 50 mile fixed-distance from the coastline has been used by the U.S. Census to estimate demographic information of the U.S. “coastal” population. This process to develop this area included land that borders the ocean and any of its saltwater tributaries, including bays and tidal rivers, and the Great Lakes. Excluded from this boundary are rivers and lakes that may be part of coastal watersheds. Therefore, for example, the tidal Potomac and the Chesapeake Bay were included as part of the coastal shoreline, while the Hudson River and Lake Pontchartrain were not. Once the coastline was delineated, a buffer was applied to identify all block groups located either partially or fully within 50 miles of this coastline boundary. The final area was the aggregated area of these block groups.

2. Areas Vulnerable to Hurricane-Force Winds

The American Society of Civil Engineers (ASCE) delineates hurricane prone areas of the eastern U.S. that are vulnerable to hurricane-force winds, that is 90 mph or greater basic wind speed. The ASCE basic wind speed is based on velocity of three-second gusts measured at 10 meters above the ground, whereas wind speeds used in the Saffir/Simpson hurricane strength scale are based on wind speeds averaged over a one-minute period. As such, a basic wind speed of 90 mph is approximately equivalent to a minimum Category I hurricane wind speed (74 mph).

Section III: Efforts to Define a Uniform National Coastal Area

The term “coastal area” has numerous delineations and applications across the coastal management community, creating uncertainty and jurisdictional complexity for state, local, and federal managers, the public and their elected representatives. NOAA’s Office of Ocean and Coastal Resource Management hosted the first National Coastal Area Workshop on February 26, 2009, in Washington D.C. to discuss the challenges and benefits of developing a single definition of coastal area under the authority of the Coastal Zone Management Act. It was recognized that defining a uniform national coastal area is a complex task, however, it was concluded that there could be many benefits of a consistent national coastal area. For further information, see the National Coastal Area Workshop Report.

Many social science data sets are collected and commonly reported using political boundaries, especially counties. As a result, “coastal counties” has emerged as common and readily recognizable framework to describe the human dimension of the coast. NOAA references two different coastal county suites for reporting demographic and economic information. The first county suite is the Coastal Watershed Counties, where land use and water quality changes most directly impact coastal ecosystems. The permanent U.S. population that resides in the Coastal Watershed counties can be thought of as "the population that most directly affects the coast." The second county suite is the Coastal Shoreline Counties, those counties that are directly adjacent to the open ocean, major estuaries, and the Great Lakes, and which due to their proximity to these waters, bear a great proportion of the full range of effects from coastal hazards (not just coastal inundation) and host the majority of economic production associated with coastal and ocean resources. The permanent U.S. population that resides in the Coastal Shoreline Counties can be thought of as "the population most directly affected by the coast." Both the Coastal Watershed Counties and the Coastal Shoreline Counties are based on 2010 county boundaries. For more detailed information on this model see The "Coast" is Complicated: A Model to Consistently Describe the Nation's Coastal Population associated peer-reviewed journal article.

Section IV: Discussion on Coastal Management Jurisdictions

The “coast” is commonly defined as a transition area between land and sea, including large inland lakes such as the Great Lakes. This delineation often includes an ocean component—the coastal ocean from the land/ocean interface out to some seaward boundary—and a land component—the coastal area from the shoreline to some inland boundary. This section discusses some of the different methods by which coastal boundaries are delineated around the land/ocean interface for the purposes of description, assessment, and management.

A. The Coastal Ocean: To a Seaward Boundary

The coastal ocean is the part of the sea that is distinguished by its proximity to the land, and there are several ways to define the seaward boundary of the coastal ocean. One example is the extent of the shallow (less than 200m deep) area of the ocean where land, ocean and atmosphere interact—which is roughly 7 percent of the surface area of the global ocean (Note: The 200m depth contour as the outer boundary of the coastal ocean is based on historical happenstance when hypsographic analyses use 200m as the shallowest isobaths (Oceanography: Oceans by Seafriends Organization)) The average depth at the continental shelf break is about 125m. As an additional example, the State of the Nation’s Ecosystem Report (Heinz Center, 2002) selected the area of “brackish water” as the coastal ocean, defined as where the ocean is influenced by fresh water from rivers and groundwater so that salinity is below that of the open ocean. The width of this area varies from a narrow area in the Pacific coast to areas as wide as 200 miles in the Atlantic coast. As a final example, the seaward boundary of the coastal ocean can be defined for political uses, such as the jurisdiction of the United States. The ocean “jurisdiction of the United States” under international law, was presented as follows in the 2004 report of the U.S. Commission on Ocean Policy.

The Baseline (0 Miles)

For purposes of both international and domestic law, the boundary line dividing the land from the ocean is called the baseline. The baseline is determined according to principles described in the 1958 UN Convention on the Territorial Sea and the Contiguous Zone and the 1982 UN Convention on the Law of the Sea, and is normally the low water line along the coast. In the United States, the definition has been further refined based on federal court decisions. The US baseline is the mean lower low water line along the coast, as shown on official U.S. nautical charts. Water bodies inland of the baseline (such as bays, estuaries, rivers, and lakes) are considered “internal waters” subject to national sovereignty.

State Seaward Boundaries (0-3 nm; 0-9 nm for Texas, Florida’s Gulf Coast, and Puerto Rico)

In the 1940s, several states claimed jurisdiction over mineral and other resources off their coasts. This was overturned in 1947, when the Supreme Court determined that states had no title to, or property interest in, these resources. In response, the Submerged Lands Act was enacted in 1953 giving coastal states jurisdiction over a region extending 3 nautical miles seaward from the baseline, commonly referred to as state waters. For historical reasons, Texas and the Gulf Coast of Florida are an exception, with state waters extending to 9 nautical miles offshore. (Note: A nautical mile is approximately 6,076 feet. All references hereafter in this Primer to miles are to nautical miles.) Subsequent legislation granted the U.S. Virgin Islands, Guam, and American Samoa jurisdiction out to 3 miles, while Puerto Rico has a 9-mile jurisdictional boundary.

The federal government retains the power to regulate commerce, navigation, power generation, national defense, and international affairs throughout state waters, sometimes called also as Federal Waters. However, states are given the authority to manage, develop, and lease resources throughout the water column and on and under the seafloor. (States have similar authorities on the land side of the baseline, usually up to the mean high tide line, an area known as state tidelands.)

In general, states must exercise their authority for the benefit of the public, consistent with the public trust doctrine. Under this doctrine, which has evolved from ancient Roman law and English common law, governments have an obligation to protect the interests of the general public (as opposed to the narrow interests of specific users or any particular group) in tidelands and in the water column and submerged lands below navigable waters. Public interests have traditionally included navigation, fishing, and commerce. In recent times, the public has also looked to the government to protect their interests in recreation, environmental protection, research, and preservation of scenic beauty and cultural heritage.

The Territorial Sea (0-12 nm)

Under international law, every coastal nation has sovereignty over the air space, water column, seabed, and subsoil of its territorial sea, subject to certain rights of passage for foreign vessels and, in more limited circumstances, foreign aircraft. For almost two hundred years, beginning with an assertion by Secretary of State Thomas Jefferson in 1793, the United States claimed a territorial sea out to 3 miles. In 1988, President Reagan proclaimed a 12-mile territorial sea for the United States, consistent with provisions in the LOS Convention. The proclamation extended the territorial sea only for purposes of international law, explicitly stating that there was no intention to alter domestic law.

The Contiguous Zone (12 to 24 nm)

International law recognizes a contiguous zone outside the territorial sea of each coastal nation. Within its contiguous zone, a nation can assert limited authority related to customs, fiscal, immigration, and sanitary laws. In 1999, President Clinton proclaimed a U.S. contiguous zone from 12 to 24 miles offshore enhancing the U.S. Coast Guard’s authority to take enforcement actions against foreign flag vessels throughout this larger area.

The Exclusive Economic Zone (12 to 200 nm)

The Law of the Sea Convention (LOS) Convention allows each coastal nation to establish an exclusive economic zone (EEZ) adjacent to its territorial sea, extending a maximum of 200 miles seaward from the baseline. Within its EEZ, the coastal nation has sovereign rights for the purpose of exploring, exploiting, conserving, and managing living and nonliving resources, whether found in ocean waters, the seabed, or subsoil. It also has jurisdiction over artificial islands or other structures with economic purposes.

In 1983, President Reagan proclaimed the U.S. EEZ, which occupies the area between 12 miles (the seaward limit of the territorial sea) and 200 miles offshore for international purposes. It also includes areas contiguous to its commonwealths, territories, and possessions. Consistent with international law and traditional high-seas freedoms, the U.S. does not generally assert control over surface or submarine vessel transit, aircraft overflight, or the laying of cables and pipelines on the ocean floor, nor does it assert jurisdiction over marine scientific research in the U.S. EEZ to the same extent that most coastal nations do. The United States
requires advance consent for marine research, if and only if, any portion of the research is conducted within the U.S. territorial sea, involves the study of marine mammals, requires taking commercial quantities of marine resources, or involves contact with the U.S. continental shelf.

The Continental Shelf (12 to 200 nm or Outer Edge of Continental Margin)

The legal concept of the continental shelf has evolved over the last sixty years. A 1945 proclamation by President Truman first asserted a U.S. claim to resources of its continental shelf. This proclamation set a precedent for other coastal nations to assert similar claims over resources far from their shores. The need to establish greater uniformity was one of the driving forces behind the 1958 United Nations Convention on the Continental Shelf. However, the 1958 Convention showed limited vision, defining the continental shelf based on a nation’s ability to recover resources from the seabed. As technological capabilities improved, uncertainty began anew about the seaward boundary of a nation’s exclusive rights to continental shelf resources.

The LOS Convention generally defines the continental shelf for purposes of international law as the seafloor and subsoil that extend beyond the territorial sea throughout the natural prolongation of a coastal nation’s land mass to the outer edge of the continental margin or to 200 miles from the baseline if the continental margin does not extend that far. The legal definition of the continental shelf thus overlaps geographically with the EEZ.

Where a coastal nation can demonstrate that its continental margin extends beyond 200 miles, the LOS Convention has a complex process for asserting such claims internationally. The U.S. continental margin extends beyond 200 miles in numerous regions, including the Atlantic Coast, the Gulf of Mexico, the Bering Sea, and the Arctic Ocean. However, because the United States is not a party to the LOS Convention, it can not assert its claims through LOS Convention mechanisms.

The High Seas (Areas Beyond National Jurisdictions)

International law has long considered areas of the ocean beyond national jurisdiction to be the high seas. On the high seas, all nations have certain traditional freedoms, including the freedom of surface and submerged navigation, the freedom to fly over the water, harvest fish, lay submarine cables and pipelines, conduct scientific research, and construct artificial islands and certain other installations. These freedoms are subject to certain qualifications, such as the duty to conserve living resources and to cooperate with other nations toward this end. In addition, a nation exercising its high seas freedoms must give due regard to the interests
of other nations.

Originally defined as the area beyond the territorial seas of coastal nations, today the high seas are defined by the LOS Convention as the area seaward of the EEZs of those nations. Sixty percent of the world’s oceans remain in this zone, where the traditional freedom of the seas still prevails. Even on the high seas, the United States and other coastal nations have some limited ability to exercise governmental authority. For example, U.S. citizens on the high seas remain subject to U.S. law, as do individuals on U.S.-flagged vessels and aircraft.

 


Over the past twenty years, U.S. presidents have issued a series of proclamations changing the extent and nature of U.S. authority over the oceans. The changes, creating a territorial sea to 12 miles, a contiguous zone to 24 miles, and an exclusive economic zone to 200 miles, have not been comprehensively reflected in domestic laws. Many laws also use imprecise or inconsistent terms to refer to ocean areas, such as “navigable waters,” “coastal waters,” “ocean waters,” “territory and waters,” “waters of the United States,” and “waters subject to the jurisdiction of the United States.” These terms can mean different things in different statutes and sometimes are not defined at all. Legal disputes have already occurred over the seaward extent of jurisdiction of the Endangered Species Act and the National Environmental Policy Act. The Clean Water Act and the Oil Pollution Act both refer to the 3-mile territorial sea. Inconsistencies or ambiguities in geographic definitions have caused problems in civil and criminal cases unrelated to natural resources, such as the regulation of offshore gambling. Congress has amended some laws regulating marine commerce to reflect the 12-mile U.S. territorial sea. However, there has
been no systematic effort to review and update all ocean-related U.S. statutes and regulations.

Internationally, other countries have defined their coastal ocean in different ways. For example, Northern Island describes its coastal ocean as 12 miles seaward from baseline. For Portugal, it is seaward to the 30 m depth contour. For Croatia, it is 300 m into the sea.

B. The Coastal Area: To an Inland Boundary

The coastal area is a portion of the land that is distinguished by its proximity to the ocean. Coastal areas are diverse in function and form, dynamic, and do not lend themselves well to definition by strict spatial boundaries. There are no consistent natural boundaries that unambiguously delineate the coastal area. Nevertheless, for assessment and management purposes, a variety of methods to establish the coastal area and an associated inland boundary are utilized around the world. This section reviews various criteria that can be used to delineate the coastal area and provides example methods used by various federal and state programs.

1. Political Criteria

Existing political boundaries are a common method to define the coastal area for assessment and management purposes, and to this end, there are several national suites of “coastal counties” (see Section 1. Common Coastal County Aggregations Used in STICS for a detailed presentation of the most common coastal county aggregations). Political boundaries have also been to establish state coastal zones, under the authority of the Coastal Zone Management Act 1972. One example is the state of Minnesota that uses the nearest legal coastal townships along the shore, or approximately six miles inland to define the state’s coastal zone. In the metropolitan areas it includes also cities boundaries. To describe the Nation’s coastal and ocean economies, the National Ocean Economics Program (NOEP) relies on a tiered approach of political boundaries, including counties and zip code areas, extending inland from the shorelines of the ocean or Great Lakes. Other countries also use political boundaries to define their coastal areas, such as Malaysia and Thailand, which use district boundaries, and the Philippines, which use boundaries of coastal municipalities plus inland municipalities conducting brackish water aquaculture.

Several federal agencies and other institutes in the U.S. define the coastal area as the suite of coastal counties that are adjacent to the ocean shoreline. The number of counties however varies depending on the shoreline boundary used.

  • The Census Bureau defines the coastal county inclusion (311 counties excluding Great Lakes) as counties adjacent to water classified as either coastal water or territorial sea in their Topologically Integrated Geographic Encoding and Referencing (TIGER) system (U.S. Census Bureau  2010). NOAA defines it as counties (422 excluding Alaska and U.S. Territories) that intersect NOAA’s Medium Resolution Shoreline; this shoreline extends inland to the head of tide. (NOAA 2012e).
  • The National Ocean Economics Program defines it as counties (355 excluding U.S. Territories) that intersect, in whole or in part, state Coastal Zone as delineated under the authority of the Coastal Zone Management Act of 1972, which are adjacent to an ocean, Great Lake, or included river or bay (NOEP 2012 and personal communication with NOEP).
  • The U.S. Geological Survey defines it as counties (219 excluding Great Lakes) where some portion of the land was directly exposed to the Pacific Ocean, Atlantic Ocean, or Gulf of Mexico as identified by an intersection with the Coastal Vulnerability Index shoreline (Boruff et al. 2005).
  • FEMA defines it as counties (452 excluding unorganized atolls in American Samoa) that (1) have a coastline bordering the open ocean or Great Lakes coasts (or associated sheltered water bodies), or (2) contain FEMA-identified coastal high hazard areas (V-zones and/or Coastal A zones).  (Crowell et al. 2007 and Crowell et al. 2010). 

Coastal areas established using existing political boundaries are easily defined and easily recognized by the public, but the resulting area may or may not be have ecological, economic, and social relevance to the “coast.”

2. Fixed-Distance Inland Criteria

Establishing a fixed-distance inland from the land/ocean interface is another common method to define the coastal area. For example the U.S. Census used a fixed-distance inland boundary of 50 miles to define a national coastal area and estimate associated demographic information. Using this coastal area definition, in the year 2000, the U.S. Census estimated 137.5 million people, or 48.9 percent of the total U.S. population reside on the coast (source: http://www.census.gov/newsroom/emergencies/additional/additional_information_on_coastal_areas.htm).

In 1975 the Texas Coastal Management Program defined the Texas coastal zone as "southwest along the coast from the Sabine to the Rio Grande, seaward into the Gulf of Mexico for a distance of 10.35 miles (9 nautical miles). Other countries have also defined their coastal area using fixed-distance inland criteria. For example, Denmark uses 1.86 miles (3 km) inland from the shoreline; Northern Island uses 3 miles inland from baseline (shoreline); Portugal uses 1.2 miles (2 km) inland from the line of highest equinoctial; Costa Rica uses 656 ft (200 m) from the Mean High Water Boundary (MHWM); Sri Lanka uses 984 ft (300 m) from the MHWM; Croatia uses 0.62 miles (1 km) inland from the coastline. Fixed-distance inland critieria has also been used to describe characteristics of the global coastal area. For example, the Socioeconomic Data and Applications Center (SEDAC) established a coastal area using a 62 miles (100 km) inland boundary to determine that about 40 percent of the world’s population lives within this distance from the coast (source: SEDAC).

Coastal areas established by arbitrary distances inland are easily defined and recognizable to the public, but the resulting area may or may not have ecological, economic, and social relevance to the “coast.”

3. Elevation Criteria

The use of elevation to delineate the coastal area is common practice for assessment and management purposes. An example of this method is designation of the 100 year special flood hazard area (SFHA) by the Federal Emergency Management Agency (FEMA). In another example SEDAC defined the coastal area for many countries by including all land contiguous with the coast that was 10 m or less in elevation (what SEDAC referred to as the low elevation coastal zone) and estimated the urban, rural, and total population of this land area.

Selected other organizations and projects that use elevation to establish the inland extent of the coastal area include:

Coastal areas established through elevation require robust elevation data and may not be readily recognized by the public, however, they are well suited to denote, assess, and manage areas vulnerable to coastal inundation.

4. Watershed / Geophysical Criteria

A coastal watershed is a unit of land that drains to surface water bodies including lakes, rivers, estuaries, and bays that ultimately empty into the coastal ocean. Coastal watersheds transcend political, social, and economic boundaries, and have been commonly used to define coastal areas. An example framework of estuarine and fluvial drainage units that can be used to delineate a watershed-based coastal area is NOAA’s Coastal Assessment Framework (CAF), as can the USGS Hydrologic Units watershed framework (see Section 2. Coastal Management Jurisdictions Used in STICS for a detailed presentation of the CAF and USGS Hydrologic Units).

Coastal areas established delineated using coastal watersheds have direct relevance to the ecology of the “coast” and managing coastal resources, but may not be easily recognized by the public.

5. Other Physical Criteria

Some coastal areas are defined by prominent physical landmarks. More often physical landmarks are used to define the seaward extent of a coastal or marine management area, they are used occasionally to define the inland extent of a coastal area. For example, in the Lingayen Gulf, an extension of the South China Sea on Luzon in the Philippines, a coastal area for planning purposes was defined by including five non-coastal municipalities that were located in brackish waters.

Another example comes from the USFWS National Wildlife Refuge System. When tasked with identifying the refuges that were “coastal,” USFWS first identified what refuges were located in tidally influenced waters, which resulted in a list of 169 refuges. USFWS then looked consulted the National Wetland Inventory and added another 8 refuges based proximity to tidally-influenced wetlands. Lastly, USFWS updated their list with refuges that had submerged, intertidal, or emergent lands within the Refuge’s administrative boundaries that have saline soils.

Another criterion that could be considered when defining coastal areas is hurricane prone areas based on subjectivity to hurricane-strength wind speeds. The American Society of Civil Engineers (ASCE) delineates areas of the U.S. prone to hurricane-force winds, which includes lands on the U.S. Atlantic Ocean and Gulf of Mexico coasts subject to wind speeds greater than 90 mph.

6. Mixed Criteria

Coastal areas can be delineated using a mix of the criteria described above. An example is the current delineation of the U.S. coastal zone under the authority of the Coastal Zone Management Act (CZMA). The CZMA provides for each state to define its coastal zone for management purposes, and collectively the states use a range of political, fixed-distance inland, watershed, and other criteria (see Section 2. Coastal Management Jurisdictions Used in STICS for further information on U.S. state coastal zones).

Internationally, other countries use a combination of distance-to-coast and elevation information to define coastal areas, for example, land that within 100 km of the coast and less than 50 meters in elevation.