| Overwater Structures in Navigable Lakes of Washington State | |
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Data format: Personal GeoDatabase Feature Class File or table name: Overwater_Structures_Lakes Coordinate system: Lambert Conformal Conic Theme keywords: Overwater Structures, docks, lakes, buildings, Shoreline Modification, bridges, floats, marinas, HCP Habitat Conservation Plan |
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Abstract:
The Overwater Structures Lake layer is made up of thousands of digitized overwater structures such as docks, bridges, floats, structural support fill, and other structures such as floating homes. Structures were digitized from three (3) foot/one (1) meter resolution color orthophotos taken between 2002 to 2006 by either the Washington State Department of Natural Resources (Washington DNR) or the United States Department of Agriculture National Agriculture Imagery Program (NAIP). The data layer is statewide and includes all lakes classified as definitely or probably navigable by the Revised Code of Washington (RCW 90.56.010(15)), as well as a limited set of lakes classified as possibly navigable. The datatable has been standardized so that overwater structures can be looked up based on structure type, structure size, waterbody name, township, county, or waterbody navigability. NOTE: While Washington DNR is willing to share the data with other entities, there are currently no plans to QA/QC the data or maintain it. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
The Overwater Structures Lake layer is made up of thousands of digitized overwater structures such as docks, bridges, floats, structural support fill, and other structures such as floating homes. Structures were digitized from three (3) foot/one (1) meter resolution color orthophotos taken between 2002 to 2006 by either the Washington State Department of Natural Resources (Washington DNR) or the United States Department of Agriculture National Agriculture Imagery Program (NAIP). The data layer is statewide and includes all lakes classified as definitely or probably navigable by the Revised Code of Washington (RCW 90.56.010(15)), as well as a limited set of lakes classified as possibly navigable. The datatable has been standardized so that overwater structures can be looked up based on structure type, structure size, waterbody name, township, county, or waterbody navigability. NOTE: While Washington DNR is willing to share the data with other entities, there are currently no plans to QA/QC the data or maintain it.
To map and quantify the extent of overwater structures on and adjacent to state-owned aquatic lands as part of the take analysis for a proposed State-owned Aquatic Lands Habitat Conservation Plan (HCP).
Date range of orthos used as digitization reference
Use must conform to the Washington DNR license agreement
1111 Washington Street SE
The accuracy of these polygons is based on the accuracy of the 3 foot/1 meter resolution orthophotos used as digitization reference. There may be slight spatial differences between the DNR orthophotos and the USDA NAIP orthophotos due to differences in photogrammetry methods (most notable when viewing taller structures) or from differences associated with "on the fly" projection of the USDA NAIP orthos. There may also be errors associated with the ortho photo quality, namely due to shadow, glare on the water, or random objects with a similar appearance as an overwater structure.
The resolution of the orthophotos used for digitization reference is 3 feet, with a horizontal accuracy of + or - 10 feet. The observed difference noted between "on the fly" vs. manual reprojection of non-DNR orthophotos was roughly 6 feet.
Statewide color orthophotos
Color orthophotos for specific regions of the state
Three foot resolution orthophotos were used as the underlying reference layer for the manual digitization (outlining) of various types of overwater structures.
The newly created polygon is classifed based on structure type, characteristics, and location
The area of the overwater structure expressed in hectares
Water body GNIS (Geographic Names Information System) name. The name of the water body as contained within the USGS GNIS database (http://geonames.usgs.gov/domestic/index.html). Not all features will have a GNIS name and number, but all features with GNIS names will have GNIS numbers and vice versa
General OWS type
Feature geometry.
ESRI
Whether the structure decking was complete or not
Lenght (feet) of OWS
Observation whether or not the overwater structure included multiple structure types (such as including both a building and a dock)
Area (Square Feet) of the Overwater Structure
Was a boat included in OWS footprint
Orthophoto source, code ID, resolution, and year.
Internal feature number.
ESRI
Area of OWS in acres
Public Land Survey System Township (PLSS_Township). Overwater structures are organized based on the nearest township. If an onshore structure crosses two or more townships the PLSS_Township for the shoreward portion of the structure is assumed. If the overwater structure crosses two or more townships, but does not touch land the PLSS_Township with the majority of the township is assumed
Cartographer comments about the digitization or classification of an overwater structure. Used for clarification of overwater structure definition, or for notation of observed features. Examples of this would be to note if the overwater structure intersects with two or more townships or it the structure is within a broad intertidal area such as a mud flat. The comments field is not intended to be used as a variable for data analysis, but rather as a method to understand data assumptions or characteristics.
Additional detail on the type of overwater structure (ex. st_type=bridge, os_detail=road)
A more detailed description of Overwater Structure type
The OS_ID_CODE is made up of three parts to identify general water body type, specific water body code, and individual overwater structure identification number. The first two letters of the code is an abbreviation for the general water body type (LK= Lake, RV= River, MA = Marine). The first four numbers of the code represent the specific water body (for rivers, a numeric code based on the alphabetical order of the water body name). The last five numbers of the code represent the individual overwater structure identification number. In general, the last five numbers for lakes will be between 0-39,999; marine 40,000-69,999; and rivers 70,000-99,999.
Unique identifier of cartographer
Navigabilty of waterbody where OWS is located based on Washington State's definition per WAC 332-30-106(41)
County name where OWS is located
Observation whether or not the overwater structure included multiple structure types (such as including both a building and a dock)
Date that the overwater structure was digitized
Date Orthophotos was flown
The attributes used for this project were selected to better clarify the physical characteristics or description of a each overwater structure, as well as to provide insight to their location in reference to other features of the politically defined landscape.
1111 Washington Street SE
1111 Washington Street SE