Publication dates of the USGS maps used as sources range from 1980 to 1986. The maximum estimated error in horizontal position based on National Map Accuracy Standards is 167 feet. Experience shows that actual locational error appears to be greater, especially in localized areas.
Attributes include feature type and coincidence, among others.
The data are stored in geographic coordinates, NAD83.
These data have not been updated since 1986 (except in one isolated instance), nor are there plans to do so. Accordingly, these data are for general reference and cartographic use. This is a legacy dataset made available as a convenience. The data are not suitable for showing all local streams or shorelines at a large scale for any given area. These data can be considered to be essentially out of date and unmaintained.
These data and most of the accompanying metadata were originally developed and maintained under the auspices of the Illinois Geographic Information System (IGIS) initiative (circa 1986). Maintenance of the metadata was transferred to ISGS circa 1996.
This dataset serves as an important base cartographic element for many types of maps and has been widely distributed and used outside the ISGS. The data set was not and is not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS as a reference base layer for maps, the data set has no legal basis in the definition of boundaries or property lines.
Links to these are provided in the Cross References section.
Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, firstname.lastname@example.org. License fees and a license agreement may be required, depending on the proposed usage.
Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data. Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.
The data do not replace the need for detailed site-specific studies.
Arc: append streams line features (the 102 coverages were listed here) end
The new coverage was reprojected from customary ISGS Lambert projection, NAD27 to geographic coordinates, NAD83, double-precision. That coverage was imported into ISGS SDE enterprise database, following steps outlined in ISGS procedure GISDB_0009.
Spatial index grid size was set at 0.125 degrees.
Metadata was updated.
ENR1, ENR2, ENR ENR1 and ENR2 are concatenated to create ENR Code composed of one or two parts describing the type of feature represented. Derived from original coding in DLG files. From Standards for Digital Line Graphs, USGS, 1987.
Values for ENR1 include: 200 - shoreline 201 - manmade shoreline 203 - indefinite shoreline 204 - apparent limit, delineates patterned areas on quads 412 - stream 414 - ditch of canal 415 - aqueduct 418 - siphon 419* - boundary of a channel in a waterbody
Values for ENR2 include: 406 - dam 407 - canal lock or sluice gate 409 - gate (flood, tidal, head, check) 605 - right bank 606 - left bank 610 - intermittent 611 - abandoned
These codes are not consistent with USGS coding but were added by IGIS staff to originally unattributed arcs.
Special cases of minor code values: 202 (closure): This value appears both alone and as a modifier for streams (412) and ditches (414). This code is maintained as 202 in ENR2. ENR codes containing 202 include 000202, 412202 & 414202.
406 (dams): This value appears both alone and as a modifier to shorelines (200). This code is maintained as 406 in ENR2. Possible codes include 000406 and 200406.
602 (overpassing) 617 (underpassing): These descriptors are modifiers for a number of feature types including siphons (418), streams (412) and ditches (414). They are carried in item OV-UN. 1 indicates overpassing and 2 indicates underpassing.
Precedence: In a few limited cases, information coded in the original data was discarded due to how the codes were restructured. These situations are resolved as follows:
intermittent and closure line are coded as closure lines (202) intermittent and abandoned are coded as intermittent (610) 414 610 202 ditch intermittent closure. Closure supersedes 414 610 611 ditch intermittent abandoned. Interim. supersedes
OV-UN Overpassing indicates a feature that passes over rather than intersects another feature, such as an aqueduct. Note that this is not maintained topologically. Underpassing indicates a feature passing under another feature, such as an aqueduct. from Standards for Digital Line Graphs, USGS, 1987. Domain: 0 - Neither 1 - overpassing 2 - underpassing
COINCIDENT DLG feature code indicating the type of feature in other DLG data sets with which this arc is coincident. This attribute was carried over form the original DLG data set and has not been checked or maintained. Refer to USGS DLG Users Guide. from Standards for Digital Line Graphs, USGS, 1987. Domain: See USGS DLG Users Guide 2.
HLINE Six-digit integer previously used for archival purposes.
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Illinois Natural Resources Geospatial Data ClearinghouseGenerated by mp version 2.8.25 on Thu Apr 02 09:54:13 2009