New York State tidal wetlands south of the Tappan Zee Bridge, as of 1974, for tidal wetlands trend analysis.
To provide a digital representation of tidal wetlands in New York State as of 1974 for tidal wetlands trend analysis
1. These digital data do not constitute an official tidal wetlands map. The user of the data assumes all responsibility for any action that might result from the use of the data. All measurements and positions are approximate. 2. The official tidal wetlands inventory maps from which the wetland boundaries were digitized are based on aerial photographs that, though best-fitted to NYSDOT planimetric maps, are nonetheless not ortho-rectified. This, along with shoreline changes that have occurred since 1974 (year of the photography), means that some of the digitized wetland boundaries may not align well with current orthophotography or with other GIS data layers. 3. Some of the wetland boundaries in the digital data do not appear on the official tidal wetlands inventory maps. These include boundaries added to correct errors/omissions identified during digitizing of the maps, and others added in unmapped 2,000m x 2,000m blocks to connect "dangling" boundaries on adjacent mapped blocks. 4. Some wetlands labeled as category FC on the official tidal wetlands inventory maps may be coded as HM or IM in the digital data. The re-coding (done during some of the earlier digitizing efforts) was intended to indicate the dominant vegetation type, since this is what determines the regulatory value of FC wetlands. Although the codes for some of these wetlands were reverted to FC during the final digitizing effort, FC-mapped wetlands coded as HM or IM in the digital data may still exist in the areas of Moriches, Quantuck and Shinnecock Bays, Fishers Island and the Town of East Hampton.
publication date
1. The NYS DEC asks to be credited in derived products. 2. Secondary Distribution of the data is not allowed. 3. Any documentation provided is an integral part of the data set. Failure to use the documentation in conjunction with the digital data constitutes misuse of the data. 4. Although every effort has been made to ensure the accuracy of information, errors may be reflected in the data supplied. The user must be aware of data conditions and bear responsibility for the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions.
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Mylar maps were made by enlarging 1974 color infrared aerial photography at 1 inch equals 1,000 feet and best fitting the enlargement to New York State Department of Transportation maps at a scale of 1 inch equals 2,000 feet. Each map, 2,000m x 2,000m, is identified with a six digit New York Transverse Mercator coordinate (NAD27), e.g. 600-526 (600 is 600,000 and 526 is 4,526,000). The maps were not subject to aerial triangulation.
An edge-matched vector line was digitized in ARC/INFO from mylar maps of the Official New York State Tidal Wetlands Inventory at 1 inch equals 200 feet. The vector lines were used to build polygons that were coded with the tidal wetlands category.
Data from several digitizing projects were combined into a single ARC/INFO coverage and projected from NAD27 to NAD83.
Unique number identifying the polygon.
NYSDEC
A numeric code corresponding to the tidal wetlands category
NYSDEC
SM. Coastal Shoals, Bars and Mudflats.
NYSDEC
LZ. Littoral Zone.
NYSDEC
FC. Formerly Connected.
NYSDEC
IM. Intertidal Marsh.
NYSDEC
FM. Fresh Marsh.
NYSDEC
HM. High Marsh.
NYSDEC
AA. Adjacent Area.
NYSDEC
DS. Dredged Spoil.
NYSDEC
HL. Hole Area includes areas that do not contain tidal wetlands or adjacent area.
NYSDEC
Acreage of the polygon calculated by multiplying the AREA field (see below) by 0.0002471. At the 3 decimal places allotted to this item, a few very small polygons have zero acreage.
NYSDEC
Internal feature number.
ESRI
A two-letter code for the tidal wetlands category. With the exception of AA and HL (see below), these are the codes that are labeled on the 1974 official tidal wetlands inventory maps. Regulated areas (as noted below) are areas that are regulated by law and require a permit review. Management areas (as noted below) are areas that have been identified for management purposes. Management areas are non-tidal areas but may require permit review as adjacent areas or as other protected areas.
NYSDEC
Coastal Shoals, Bars and Mudflats. Regulated area. The tidal wetland zone that at high tide is covered by saline or fresh tidal waters, at low tide is exposed or is covered by water to a maximum depth of approximately one foot, and is not vegetated.
NYSDEC
Littoral Zone. Regulated Area. The tidal wetland zone that includes all lands under tidal water which are not included in any other category and which are six feet or less under water at mean low tide. Note, however, that portions of some areas labeled as LZ on the official tidal wetlands inventory maps (and in the digital data) are almost certainly more than six feet under water at mean low tide. See 6NYCRR Part 661.4 for more detail.
NYSDEC
Formerly Connected. The tidal wetland zone in which normal tidal flow is restricted by man-made causes. Phragmites sp. is the dominant vegetation.
NYSDEC
Intertidal Marsh. Regulated Area. The vegetated tidal wetland zone lying generally between average high and low tidal elevation in saline waters. The predominant vegetation in this zone is low marsh cordgrass, Spartina alterniflora. See Supplemental Information 4.
NYSDEC
Fresh Marsh. Regulated Area. The tidal wetland zone found primarily in the upper tidal limits of riverine systems where significant freshwater inflow dominates the tidal zone. Species normally associated with this zone include narrow leaved cattail, Typha angustifolia; the tall brackish water cordgrass, Spartina pectinata and/or S. cynosuroides; and the more typically emergent fresh water species such as arrow arum, Peltandra; pickerel weed, Pontederia; and cutgrass, Leersia.
NYSDEC
HM. High Marsh. Regulated area. The normal uppermost tidal wetland zone usually dominated by salt meadow grass, Spartina patens; and spike grass, Distichlis spicata. This zone is periodically flooded by spring and storm tides and is often vegetated by low vigor, Spartina alterniflora and Seaside lavender, Limonium carolinianum. Upper limits of this zone often include black grass, Juncus gerardii; chairmaker's rush, Scirpus sp; marsh elder, Iva frutescens; and groundsel bush, Baccharis halimifolia. See Supplemental Information 4.
NYSDEC
Adjacent Area. Regulated area. Adjacent area shall mean those land areas not included in the any of the above categories that are generally not inundated by tidal waters and that extend 300 feet landward of the most landward tidal wetlands boundary (150 feet in New York City) or to an elevation of ten feet. See 6NYCRR Part 661.4 for more detail. Note that AA areas are not explicitly labeled on the tidal wetlands inventory maps. Areas of the tidal wetlands inventory maps not labeled with a tidal wetlands category were assigned a category of AA (Adjacent Area) in the digital data by default. Portions of these AA-coded polygons do not meet the legal definition (per 6NYCRR Part 661.4) of an Adjacent Area.
NYSDEC
Dredged Spoil. Regulated area. All areas of fill material. Labeled "ds" on 1974 tidal wetlands inventory maps.
NYSDEC
Hole Area includes areas that do not contain tidal wetlands or adjacent area. Management area. These areas, which are not covered by 1974 tidal wetlands inventory maps, represent polygons formed in the digital data by surrounding mapped areas. In some cases, areas that might otherwise have been considered HL had tidal wetland polygons added during digitizing to complete wetlands on adjacent mapped areas. See Supplemental Information 3. Note also that this category is not included in the default legend that loads with the theme from the MHDB Data Selector.
NYSDEC
Feature geometry.
ESRI
Feature geometry.
ESRI
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The New York State Department of Environmental Conservation (NYSDEC) provides these geographic data "as is". NYSDEC makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. NYSDEC further makes no warranty, either expressed or implied, regarding the condition of the product or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on a computer system at NYSDEC, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. NYSDEC shall not be held liable for improper or incorrect use of the data described and/or contained herein.
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