Connecticut Hydrography Line includes the line features of a layer named Hydrography. Hydrography is a 1:24,000-scale, polygon and line feature-based layer that includes all hydrography features depicted on the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps for the State of Connecticut. This layer only includes features located in Connecticut. These hydrography features include waterbodies, inundation areas, marshes, dams, aqueducts, canals, ditches, shorelines, tidal flats, shoals, rocks, channels, and islands. Hydrography is comprised of polygon and line features. Polygon features represent areas of water for rivers, streams, brooks, reservoirs, lakes, ponds, bays, coves, and harbors. Polygon features also depict inundation areas, marshes, dams, aqueducts, canals, tidal flats, shoals, rocks, channels, and islands shown on the USGS 7.5 minute topographic quadrangle maps. Line features represent single-line rivers and streams, aqueducts, canals, and ditches. Line features also enclose all polygon features in the form of natural shorelines, manmade shorelines, dams, closure lines separating adjacent waterbodies, and the apparent limits for tidal flats, rocks, and areas of marsh. The layer is based on information from USGS topographic quadrangle maps published between 1969 and 1984 so it does not depict conditions at any one particular point in time. Also, the layer does not reflect recent changes with the course of streams or location of shorelines impacted by natural events or changes in development since the time the USGS 7.5 minute topographic quadrangle maps were published. Attribute information is comprised of codes to identify hydrography features by type, cartographically represent (symbolize) hydrography features on a map, select waterbodies appropriate to display at different map scales, identify individual waterbodies on a map by name, and describe feature area and length. The names assigned to individual waterbodies are based on information published on the USGS 7.5 minute topographic quadrangle maps or other state and local maps. The layer does not include bathymetric, stream gradient, water flow, water quality, or biological habitat information. This layer was originally published in 1994. The 2005 edition includes the same water features published in 1994, however some attribute information has been slightly modified and made easier to use. Also, the 2005 edition corrects previously undetected attribute coding errors.
In 2004, the State of Connecticut Department of Environmental Protection developed automated procedures to systematically maintain feature topology and attribute integrity for a set of related hydrography data maintained by the agency. These layers include Hydrography Master, Hydrography, Waterbody Master, Waterbody, Named Waterbody Master, and Named Waterbody. Automated procedures were developed using ArcInfo Workstation 8.3 software and the Arc Macro Language (AML) as a scripting environment and recorded in an AML file named MAKECOVER.AML for the hydrography category of data for the State of Connecticut, Department of Environmental Protection. The MAKECOVER.AML derives all related hydrography layers from one Hydrography Master layer. For additional information related to the original source of data from the U.S. Geological Survey, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
Publication dates of the USGS 7.5 minute topographic quadrangle maps for the State of Connecticut through 1984.
Hydrography represented as line features. Line features represent single-line rivers and streams, aqueducts, canals, and ditches. Line features also enclose all polygon features in the form of natural shorelines, manmade shorelines, dams, closure lines separating adjacent waterbodies, and the apparent limits for tidal flats, rocks, and areas of marsh. (Source: State of Connecticut, Department of Environmental Protection and U.S. Geological Survey, National Mapping Program)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
Hydrography Arc Code. Numeric values that identify hydrography line feature types. These codes are based on the original 1:24,000-scale USGS DLG Hydrography Major and Minor codes, but have been modified by CT DEP to add to or combine USGS classifications. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 0 | Not Hydrography |
| 109 | Sewage Disposal Pond border |
| 200 | Shoreline for Stream, Lake and Open Water polys |
| 201 | Manmade Shoreline |
| 202 | Closure Line separating adjacent Open Water polys |
| 203 | Indefinite Shoreline |
| 204 | Apparent Limit of Flat and Sand polygon areas |
| 205 | Defines extent of coastal bays and harbors |
| 206 | Apparent Limit of Marsh polygon areas |
| 401 | Falls |
| 406 | Dam or Weir |
| 407 | Canal, Lock, or Sluice Gate |
| 408 | Spillway |
| 409 | Gate (Flood, Tidal, Head, Check) |
| 410 | Boundary of Rock in Open Water |
| 412 | Single line Rivers, Streams and Brooks |
| 414 | Ditch or Canal |
| 415 | Aqueduct |
| 417 | Penstock |
| 418 | Siphon |
| 419 | Boundary of Channel in Open Water |
| 601200 | Underground Shoreline |
| 601412 | Underground Stream |
| 601415 | Underground Aqueduct |
| 610200 | Intermittent Shoreline |
| 610412 | Intermittent Stream |
| 610414 | Intermittent Ditch or Canal |
| 611414 | Abandoned or Discontinued Ditch |
| 611415 | Abandoned Aqueduct |
| 612200 | Submerged or Sunken Shoreline |
| 612412 | Submerged or Sunken Stream |
Hydrography Arc Type. Text values that correspond to the numeric HYARC_COD attribute values. HYDRO_ARC is the English language equivalent of (decodes) the HYARC_COD field. (Source: State of Connecticut, Department of Environmental Protection)
ArcView Legend. Text field for symbolizing hydrography line feature types on a map. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Aqueduct | This category includes HYARC_COD values 415, 601415, and 611415. |
| Dam | This category includes HYARC_COD value 406. |
| Drainage Ditch | This category includes HYARC_COD 414 and 611414. |
| Dredged Channel | This category includes HYARC_COD 419. |
| Intermittent Water | This category includes HYARC_COD 610412 and 610414. |
| No Show | This category includes HYARC_COD value 0, 202, 204, 205, 206, 409, 410, 612200, and 612412. |
| Shore | This category includes HYARC_COD value 200, 201, 203, 417, 601200, and 610200. |
| Water | This category includes HYARC_COD value 109, 401, 407, 408, 412, 418, and 601412. |
Internet Mapping Software Legend. Text field for classifying and symbolizing hydrography line feature types in a simple manner for an Internet map. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Aqueduct | This category includes HYARC_COD values 415, 601415, and 611415. |
| Dam | This category includes HYARC_COD value 406. |
| Dredged Channel | This category includes HYARC_COD values 419. |
| No Show | This category includes HYARC_COD values 0, 202, 204, 205, 206, 409, 410, 612200, and 612412. |
| Water | This category includes HYARC_COD values 109, 200, 201, 203, 401, 407, 408, 412, 414, 417, 418, 601200, 601412, 610200, 610412, 610414, and 611414. |
Coastal Arc Code. Identifies line features that are landward and seaward of a series of connecting hydrography line features that define a shoreline along the coast. These connecting hydrography line features that define the shoreline along the coast are referred to as Coastline Arcs and have a COASTA_COD value of 2. Coastline Arcs define a cartographic boundary that separates inland (landward) hydrography from coastal (seaward) hydrography features. This shoreline boundary does not represent a line of demarcation between tidal and non-tidal waters or between fresh, saline and brackish waters. Rather, these features define a standard shoreline boundary that is often incorporated into other layers compiled at 1:24,000 scale for consistency. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 1 | Inland Arcs. Line features that are inland (landward) of the line of Coastline Arcs, which have COASTA_COD values of 2. |
| 2 | Coastline Arcs. Line features that define a coastline that separates inland from coastal hydrography features. This is a cartographic boundary that often defines the shoreline in other 1:24,000-scale datalayers published by the State of Connecticut, Department of Environmental Protection. Note, this boundary line does not represent a line of demarcation between tidal and non-tidal waters or between fresh, saline and brackish waters. |
| 3 | Island Interior Arcs. Line features that separate smaller polygon features within Coastal Island polygons. For example, a line that separates a marsh area on an island from the area where there is not marsh on the island. |
| 4 | Island Coastline Arcs. Line features that define the shorelines for Coastal Island Polygon features. Coastal Island Polygon features have a COASTP_COD value of 2. |
| 5 | Open Water Arcs. Line features seaward of the line of Coastline Arcs that outline Coastal Water Polygon features. Coastal Water Polygon features are Hydrography polygon features with a COASTP_COD valule of 3. For example, types of Open Water Arcs include a line separating a tidal flat polygon from an open water polygon (apparent tidal flat limit), or a line between an open water polygon that represents a coastal bay from the larger open water polygon representing the larger area of Long Island Sound. |
Coastal Arc Type. Text values that correspond to the numeric COASTA_COD attribute values. COAST_ARC is the English language equivalent of (decodes) the COASTA_COD field. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Inland Arcs | Inland Arcs |
| Coastline Arcs | Coastline Arcs |
| Island Interior Arcs | Island Interior Arcs |
| Island Coastline Arcs | Island Coastline Arcs |
| Open Water Arcs | Open Water Arcs |
Named Waterbody Arc Code - A numeric code used to flag and classify hydrography line features that are part of named and unnamed waterbodies. Named waterbodies are defined as features with STREAM_NO, STREAM_NO2, LAKE_NO, LAKE_NO2, BAY_NO, BAY_NO2, HARBOR_NO, HARBOR_NO2, SOUND_NO, or SOUND_NO2 values greater than 0. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 1 | Unnamed Feature. A Hydrography feature that is not part of a named or unnamed waterbody. Typically, these are apparent limits of marsh polygons. |
| 2 | Named Single Line Stream. A named river, stream or brook represented as a single line feature. |
| 3 | Named Waterbody Shoreline. The shoreline of a named waterbody polygon feature. |
| 4 | Named Waterbody Interior Line. A hydrography line feature that is part of a named waterbody, but not typically displayed on a map such as a closure line separating open water polygons or an apparent limit of tidal flats or sand polygons. |
| 5 | Significant Unnamed Waterbody. An unnamed hydrography feature that is significant because it connects to (is between) hydrography features that are named. |
| 7 | Unnamed Single Line Stream. An unnamed river, stream or brook represented as a single line feature. |
| 8 | Unnamed Waterbody Shoreline. The shoreline of an unnamed waterbody polygon feature. |
Named Waterbody Arc Type. NAMED_ARC is the English language equivalent of (decodes) the NAMEDA_COD field. (Source: State of Connecticut, Department of Environmental Protection)
Scale Level. A numeric code that defines scale range levels for features. Scale Level values range from 1 to 6. More features are included in the higher Scale Levels. For example, Scale Level 1 includes only a few major rivers and is intended for a small map of Connecticut. Conversely, Scale Level 6 includes all waterbodies and is intended for more detailed maps displayed at about 1:24,000 scale. Use the Scale Level attribute to specify a definition query that displays a particular set of features, for example SCALELEVEL = 1. Then set the appropriate range of scale (e.g. from 1,000,001 to 3,000,000 scale) for the layer, according to application (mapping) need. Note, Scale Levels are additive so include all Scale Levels below the desired level in a definition query. For example, use the following SQL expression to query for Scale Level 4 features - SCALELEVEL IN (1,2,3,4). Note the use of the IN (INCLUDE) operator in the SQL expression. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 1 | Scale Level 1. Recommended scale range - 1:1,000,001 to 1:3,000,000. Includes 11 rivers. |
| 2 | Scale Level 2. Recommended scale range - 1:500,001 to 1:1,000,000. Includes 19 rivers and 5 lakes. |
| 3 | Scale Level 3. Recommended scale range - 1:200,001 to 1:500,000. Includes 109 rivers and 13 lakes. |
| 4 | Scale Level 4. Recommended scale range - 1:100,001 to 1:200,000. Includes mainstem rivers for each Subregional Drainage Basin. Includes 301 rivers and 137 lakes. |
| 5 | Scale Level 5. Recommended scale range - 1:50,001 to 1:100,000. Includes 1532 rivers and 1076 lakes greater than 5 acres in size. |
| 6 | Scale Level 6. Recommended scale range - 1:1 to 50,000. Includes all rivers and lakes. |
Stream Number - ID Number of named stream (for single-line stream) or named stream on left side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Stream Name - Name of stream (for single-line stream) or name of stream on left side of line feature. STREAM is the English language equivalent of (decodes) the STREAM_NO field. (Source: State of Connecticut, Department of Environmental Protection)
Stream Number 2 - ID Number of named stream on right side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Stream Name 2 - Name of stream on right side of line feature. STREAM2 is the English language equivalent of (decodes) the STREAM_NO2 field. (Source: State of Connecticut, Department of Environmental Protection)
Lake Number - ID Number of named lake on left side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Lake Name - Name of lake on left side of line feature. LAKE is the English language equivalent of (decodes) the LAKE_NO field. (Source: State of Connecticut, Department of Environmental Protection)
Lake Number 2 - ID Number of named lake on right side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Lake Name 2 - Name of lake on right side of line feature. LAKE2 is the English language equivalent of (decodes) the LAKE_NO2 field. (Source: State of Connecticut, Department of Environmental Protection)
Bay Number - ID Number of named bay or cove on left side of line feature. Bays are subunits of Harbors. (Source: State of Connecticut, Department of Environmental Protection)
Bay Name - Name of bay or cove on left side of line feature. Bays are subunits of Harbors. BAY is the English language equivalent of (decodes) the BAY_NO field. (Source: State of Connecticut, Department of Environmental Protection)
Bay Number 2 - ID Number of named bay or cove on right side of line feature. Bays are subunits of Harbors. (Source: State of Connecticut, Department of Environmental Protection)
Bay Name 2 - Name of bay or cove on right side of line feature. Bays are subunits of Harbors. BAY2 is the English language equivalent of (decodes) the BAY_NO2 field. (Source: State of Connecticut, Department of Environmental Protection)
Harbor Number - ID Number of named harbor on left side of line feature. Harbors are comprised of Bays. (Source: State of Connecticut, Department of Environmental Protection)
Harbor Name - Name of harbor on left side of line feature. Harbors are comprised of Bays. HARBOR is the English language equivalent of (decodes) the HARBOR_NO field. (Source: State of Connecticut, Department of Environmental Protection)
Harbor Number 2 - ID Number of named harbor on right side of line feature. Harbors are comprised of Bays. (Source: State of Connecticut, Department of Environmental Protection)
Harbor Number 2 - Name of harbor on right side of line feature. Harbors are comprised of Bays. HARBOR2 is the English language equivalent of (decodes) the HARBOR_NO2 field. (Source: State of Connecticut, Department of Environmental Protection)
Sound Number - ID Number of sound on left side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Sound - Name of sound on left side of line feature. SOUND is the English language equivalent of (decodes) the SOUND_NO field. (Source: State of Connecticut, Department of Environmental Protection)
Sound Number 2 - ID Number of sound on right side of line feature. (Source: State of Connecticut, Department of Environmental Protection)
Sound - Name of sound on right side of line feature. SOUND2 is the English language equivalent of (decodes) the SOUND_NO2 field. (Source: State of Connecticut, Department of Environmental Protection)
Calculated length of feature in miles. Note, LENGTH_MI values are not automatically updated after modifying feature geometry (shape). Values must be recalculated after features are edited, simplified, generalized, clipped, dissolved, etc. (Source: State of Connecticut, Department of Environmental Protection)
Includes linear and polygonal features for rivers, streams, brooks, reservoirs, lakes, ponds, bays, coves, harbors, marshes, dams, aqueducts, canals, drainage ditches, shorelines, tidal flats, submerged rocks, channels, and islands published on the U.S. Geological Survey 7.5 minute topographic quadrangle maps. Information encoded about features includes hydrography type classification, two standard symbology classification schemes, waterbody names, flags for named features, levels for mapping at different scales, feature area in acreage, and feature length in miles. Use the AV_LEGEND attribute to symbolize features by type. Use the IMS_LEGEND attribute to more generally symbolize the features by type. To define a layer that only includes named waterbodies, query line and polygon features for NAMEDP_COD and NAMEDA_COD values greater than 0. To define a layer that only includes named lakes, query the line and polygon features for LAKE_NO and LAKE_NO2 values greater than 0. To define a layer that only includes named streams, query the line and polygon features for STREAM_NO and STREAM_NO2 values greater than 0, and so on. To define a layer that only includes the Connecticut River, query line and polygon features for STREAM_NO and STREAM_NO2 equal to 374. The Stream number for the Connecticut River is 374. Each stream, lake, bay, and harbor can be queried by Id number. To define a layer that includes features typically displayed on a map, exclude all unnecessary features by querying the line and polygon features for AV_LEGEND not equal to "No Show" or IMS_LEGEND not equal to "No Show". Typically, line features with the "No Show" classification enclose Hydrography polygon features that are not outlined on a map. Examples of line features typically not shown on a map include closure lines separating adjacent open water polygons, boundaries defining bay and harbor extents, apparent limits of marsh polygons, apparent limits of rock polygons, apparent limits of tidal flat polygons, underground shorelines, and submerged streams. Define layers of hydrography for various map scale ranges by querying line and polygon features on SCALELEVEL values.
For additional information related to the original source of data from the U.S. Geological Survey, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
The named waterbody information incorporated into the Hydrography, Waterbody and Named Waterbody layers was originally compiled and mapped by James Bogar, a Cartographer with the State of Connecticut, Department of Environmental Protection.
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Connecticut Hydrography is 1:24,000-scale base map data. It depicts all of the hydrography information published on the USGS topographic quadrangle maps. For base map purposes, use this layer with other 1:24,000-scale base map data such as Roads and Trails, Railroads, Airports, and Towns. This layer may be used as a possible data source for other 1:24,000-scale layers with features that must coincide and line up with stream and shoreline features published on the USGS topographic quadrangle maps. For example, the layer includes a set of connecting line features referred to as Coastline Arcs, which define a shoreline between the Connecticut landmass and Long Island Sound. These Coastline Arc features are commonly used to close polygon features in other 1:24,000-scale layers published by the State of Connecticut, Department of Environmental Protection. For example, Coastline Arcs from the original Hydrography Master layer define the shoreline in the Waterbody, Named Waterbody, Towns, Basins, and Bedrock Geology layers. Note that related hydrography layers such as Waterbody, Waterbody Master, Named Waterbody, Named Waterbody Master, and Hydrography are all ultimately derived from the polygon and line features of the Hydrography Master layer. Typically, layers derived from Hydrography Master define a subset of polygon and line features for either the geographic area encompassed by all USGS topographic quadrangle maps that cover the State of Connecticut (a master layer) or the geographic area of the State of Connecticut, in which case the layer is clipped to the State boundary. The Hydrography layer is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)
USGS Large Scale Digital Line Graph (DLG) data are digital representations of the cartographic (base map) information published on the 1:24,000-scale, 7.5 minute topographic quadrangle maps. The USGS produces DLG data per 7.5 minute quadrangle. DLG data is organized into categories such as hydrography, boundaries, and transportation. At the time the State of Connecticut began developing the Hydrography Master layer in the late 1980's, Large Scale DLG files were available for 112 of the 115 topographic quadrangle maps necessary to cover Connecticut. Large Scale DLG files were not available for the West Springfield Mass-Conn, Springfield South Mass-Conn, and Hamden Mass-Conn quadrangle. It is important to note that the Large-Scale DLGs were produced in the 1980's at a time when the USGS was developing standards, conventions, and procedures to convert topographic quadrangle maps into digital spatial data. The Connecticut DLG files were produced by digitizing from stable-base Mylars using a digitizing tablet to capture the digital data. The features were manually digitized and attributed. Today, there are other methods available for producing DLGs. For additional DLG documentation, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
In the absence of Large Scale DLG data, the USGS provided the State of Connecticut with raster image scans of the Mylar separates used to publish the black, red, brown, and blue inks for 3 of the 115 topographic quadrangle maps that cover Connecticut. These quadrangles include West Springfield Mass-Conn, Springfield South Mass-Conn, and Hamden Mass-Conn.
Hydrography features for each quadrangle map. Each quadrangle hydrography layer is in ArcInfo Coverage format.
Hydrography Master is a 1:24,000-scale, polygon and line feature-based layer that includes all hydrography features depicted on all of the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps that cover the State of Connecticut. This data source refers to all Hydrography features combined in one statewide layer. Since initial publication in 1994, subsequent editions of the Hydrography Master layer were generated by the State of Connecticut in order to change data format, convert from NAD 27 to NAD 83, and improve the quality and accuracy of both feature geometry and feature attribute information. Consequently, over a period of many years, different versions of the Hydrography Master layer were produced. Various editions of Hydrography are reflected by those process steps in which the Hydrography Master layer is identified as both the Source Used and the Source Produced. Hydrography Master is in ArcInfo Coverage format.
This data source is a set of Mylar overlays delineating all rivers, streams, brooks, reservoirs, lakes, and ponds that appear on the 1:24,000-scale 7.5 minute topographic quadrangle maps published by the USGS for Connecticut. The names of the waterbodies shown on these Mylars are based on either waterbody names that appear on the 1:24,000-scale 7.5 minute topographic quadrangle maps, names that appear on a state map of officially named waterbodies published by the State of Connecticut in the 1930's, or local names brought to the attention of the cartographer responsible for compiling the Named Streams, Lakes and Ponds Mylars. The Named Streams, Lakes and Ponds Mylars were originally compiled and mapped by James Bogar, a Cartographer with the State of Connecticut, Department of Environmental Protection.
Connecticut is a 1:24,000-scale, polygon feature-based layer representing the geographic area encompassed by the State of Connecticut. The State of Connecticut is represented as a single polygon feature. The State boundary on the Connecticut mainland is based on 1:24,000-scale information depicted on the USGS 7.5 minute topographic maps. The State boundary in Long Island Sound is based on latitude and longitude coordinates. Connecticut is in ArcInfo Coverage format
Hydrography is a 1:24,000-scale, polygon and line feature-based layer that includes all hydrography features depicted on the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps for the State of Connecticut. The geographic extent of the data is limited (clipped) to within the State of Connecticut boundary.
Includes all line features from Hydrography where the AV_LEGEND attribute was not equal to a value of "No Show" (AV_LEGEND <> "No Show"). This selection criterion primarily includes streams, shore and dam features; and excludes closure lines separating adjacent open water polygon features and at the limit of the data layer, apparent limits of marsh polygon areas, apparent limits of flats and sand polygon areas, and extents of coastal bays and harbors. Hydrography_Line.shp is in Shapefile format.
Hydrography_Line is in GeoDatabase Feature Class format.
DLG to ArcInfo coverage format conversion - Using ESRI ArcInfo software, the State of Connecticut, Department of Enviromental Protection converted the Hydrography category for each Large Scale DLG file to ArcInfo Coverage format, resulting in one ArcInfo Coverage of polygon and line features for 112 of the 115 quadrangle areas that cover Connecticut. Each Coverage was converted from UTM to Connecticut State Plane, North American Datum of 1927 (NAD27).
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Image to vector (ArcInfo coverage) format conversion - Using ESRI ArcInfo software, the blue ink image files that depict the waterbody and marsh features on 3 of 115 topographic quadrangle maps were georeferenced to Connecticut State Plane, North American Datum of 1927 (NAD27) by registering the image corners to the corresponding quadrangle corner tics. In an interactive ArcInfo editing environment, the geogreferenced image of hydrography was displayed in the background in order to visually identify waterbody and marsh features to vectorize (digitize). Features that would have been included in the DLG Hydrorgraphy category by the USGS were were manually digitized on the screen (heads-up digitizing) at display scales greater than 1:24,000. Hydrography polygon and line features were assigned HYPOLY_COD and HYARC_COD values based on their cartographic representation on the topographic quadrangle maps. Check plots were produced to inspect digitizing quality and the assignment of HYPOLY_COD and HYARC_COD values.
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Attribute value verification - The quality and accuracy of the digitizing and coding for all hydrography features was checked by comparing the features in each ArcInfo Coverage with the water features on the published USGS topographic quadrangle maps. Visual comparisons using 1:24,000-scale paper check plots combined with automated procedures to identify inconsistent attribute coding were the primary means of evaluating and correcting obvious errors with the original DLG data. Where necessary, corrections were made to DLG major and minor codes in the ArcInfo Coverages. The original DLG major and minor codes were modified to form the HYPOLY_COD and HYARC_COD attribute in the final Hydrography Master layer.
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Quadrangle coverage edgematch - Using ESRI ArcInfo software, the individual 7.5 minute quadrangle coverages of Hydrography features were systematically edgematched. Line features that cross adjacent quadrangles were moved to make their end-point coordinates identical along quadrangle boundaries through a process of checkerboard style edgematching. Features along the edges of every other quadrangle were adjusted. The ends of rivers and shoreline segments were snapped to align with the connecting stationary features on adjacent quadrangles if their end-points were generally within 20 feet. Ends of line features were adjusted to match the location of the ends of the corresponding feature on adjacent quadrangles so that features would connect when the quadrangle coverages were appended in the subsequent process step. On occasion, there were no connecting features on adjacent quadrangles to match to so a few features abruptly end at quadrangle boundaries. These breaks are mostly due to variations in quadrangle publication dates. Varying publication dates also explain inconsistent DLG major and minor codes for some features that appear on more than one topographic map. For example, a stream that appears on two adjacent quadrangle maps may appear as an intermittent stream on one map and a perennial stream on the adjacent (more recently published) map. Consequently, HYARC_COD values for some hydrography line features change when crossing quadrangle boundaries or the HYPOLY_COD value might represent a marsh for the portion of a lake published on an adjacent quadrangle map. These inconsistencies were not resolved because the purpose was to edgematch features and preserve the feature classification of USGS topographic quadrangle maps. Data was not field checked and not updated based on aerial photography. Also, line features digitized to enclose marsh areas were not edgematched along quadrangle boundaries because these boundary lines do not actually appear on the USGS topographic quadrangle maps. These are approximate (assumed) boundaries for the general areas where marsh symbols appear on the USGS topographic quadrangle maps.
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Statewide layer creation - Using ESRI ArcInfo sofware, all (115) 7.5 minute quadrangle coverages were appended to form a single, statewide Hydrography Master layer. Linear features were unsplit (merged) to eliminate unnecessary pseudo nodes between similar features from adjacent quadrangle areas. Polygon features were merged across quadrangle boundaries. Final polygon and line feature topology was established with ArcInfo Fuzzy and Dangle tolerances verified at 4 and 10 feet, respectively. At this step in the process the Hydrography Master layer was fully attributed and ready for use. Not all data fields from the orginal DLG files were preserved by this step in the process. A new data field, AV_LEGEND, was added to more easily classify and cartographically represent features when mapping and displaying the information with software such as ArcView.
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Named waterbody attribution - Lookup data tables listing named streams, named lakes, named bays, named harbors, and named sounds were manually created based on information from the Streams, Lakes and Ponds Mylars prepared by the State of Connecticut, Department of Environmental Protection. In each lookup table, unique id numbers were assigned to each waterbody based on an alphabetic sort of records by name. For example, STREAM_NO values were calculated for named streams, LAKE_NO for named lakes, BAY_NO and HARBOR_NO for named bays and harbors, and SOUND_NO for sounds such as Long Island Sound. These unique stream, lake, bay and harbor numbers were then manually transferred to the paper copies of the Streams, Lakes and Ponds Mylar overlays. On the maps, stream numbers were placed next to named streams, lake numbers were placed next to named lakes, etc. This hard copy information was prepared as a visual a guide for subsequently attributing Hydrography line and polygon features. To prepare the Hydrography Master layer for attribution, the STREAM_NO, LAKE_NO, BAY_NO, HARBOR_NO, and SOUND_NO fields were added to the Hydrography polygon feature table. The STREAM_NO, STREAM_NO2, LAKE_NO, LAKE_NO2, BAY_NO, BAY_NO2, HARBOR_NO, HARBOR_NO2, SOUND_NO, and SOUND_NOS fields were added to the Hydrography line feature table. Note, Hydrography line features require a pair of fields for each water body type (e.g. STREAM_NO and STREAM_NO2) because the line may bound more than one Hydrography polygon feature that is named. For example, at the confluence of two named streams, the line that separates the two named stream polygons is a closure line that is attributed with the stream number for the stream on the left and the stream on the right side of the line. During an interactive editing session, polygon and line features were systematically selected and attributed with the appropriate STREAM_NO, LAKE_NO, BAY_NO, HARBOR_NO, and SOUND_NO values by referencing information prepared on the paper copies of the Streams, Lakes and Ponds Mylars. Data entry errors were identified and corrected by comparing the paper copies of the Streams, Lakes and Ponds Mylars with a series of hard copy check plots of Hydrography features labeled with stream, lake, bay, harbor, and sound numbers. Once Hydrography features were properly attributed, decode fields that store the names of the streams, lakes, bays, harbors, and sounds were added to the Hydrography polygon and line feature attribute tables by joining to the original lookup data tables. These joined fields that store waterbody names include STREAM, STREAM2, LAKE, LAKE2, BAY, BAY2, HARBOR, HARBOR2, SOUND and SOUND2. The COASTP_COD and COASTPA_COD attributes were subsequently attributed by first selecting and attributing Coastline Arcs, which define a cartographic boundary separating landward from seaward hydrography features. To form a continuous boundary line along the coast, it was necessary to introduce features that cross rivers at the first bridge upstream from Long Island Sound. These linear bridge features were copied from the Roads and Trails layer, published by the State of Connecticut, Department of Environmental Protection. All other polygon and line features were manually selected and assigned COASTP_COD and COASTA_COD values based on their relative landward and seaward orientation to Coastline Arcs. Also, new HYPOLY_COD attribute values were established to describe polygon features that represented islands and marshes that encompass entire islands (HYPOLY_COD values 121 and 111121).
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Datum conversion - Using ESRI ArcInfo software, the Hydrography Master layer was converted from the Connecticut State Plane Coordinate System of 1927 (NAD27) to the Connecticut State Plane Coordinate System of 1983 (NAD83). The NADCON (North American Datum CONversion) data transformation was used.
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Attribute enhancements - AV_LEGEND, HYDRO_POLY, HYDRO_ARC, COASTP_COD, COASTA_COD, STREAM, LAKE, HARBOR, BAY, and SOUND attributes were changed from storing abbreviated values in upper case (e.g. INTERMITTENT STREAM) to full length values in both upper and lower case (e.g. Intermittent Stream). Additionally, the IMS_LEGEND attribute was added to establish a very general classification scheme for symbolizing hydrography features with Internet mapping software environments such as ArcIMS.
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Named waterbody attribute enhancements - Previously undetected errors with STREAM_NO, STREAM_NO2, LAKE_NO, LAKE_NO2, BAY_NO, BAY_NO2 HARBOR_NO, HARBOR_NO2, SOUND_NO, and SOUND_NO2 attribute values were corrected by individually selecting, highlighting, zooming to, and inspecting features for each named waterbody. Resolving errors with these attribute values ocassionally uncovered features with errors with HYARC_COD and HYPOLY_COD attribute values, which were also corrected. Errors were discovered and corrected for hundreds of features. Two new fields, NAMEDA_COD and NAMEDP_COD and their decode fields, NAMED_ARC and NAMED_POLY, were added to easily distinguish named from unnamed waterbody features. The SCALELEVEL attribute was added to define scale range levels for Hydrography polygon and line features. Using Arc Macro Language (AML), an automated process (MAKECOVER.AML) was developed to maintain consistent attribute values by programmatically joining lookup data tables to decode numeric code fields and basing certain attribute information on polygon and line feature topology relationships. The MAKECOVER.AML also created this particular copy of Hydrography that is clipped to the State of Connecticut boundary.
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Create 2005 Edition of Hydrography - The automated process (software program), MAKECOVER.AML, developed for the previous process step was executed in 2005 in order to create a 2005 edition (copy) of Hydrography that captures recent corrections and enhancements made to the layer. Note, this particular run of the MAKECOVER.AML created a copy of the Hydrography ArcInfo coverage that is clipped to the State of Connecticut boundary. The name of the resulting coverage is HYDRO instead of HYDROMASTER, which is the name of the ArcInfo coverage that is not clipped to the State boundary. Prior to 2005, the Hydrography layer in ArcInfo Coverage format that was clipped to the state of Connecticut boundary was named HYDROCT.
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Export to Shapefile format - Converted line feature data from an ArcInfo coverage named HYDRO to a Shapefile named Hydrography_Line.shp. Excluded the FNODE#, TNODE#, LPOLY#, RPOLY#, LENGTH, HYDRO#, and HYDRO-ID attributes from the Shapefile because their values are only maintained by ArcInfo software with data that is in ArcInfo Coverage format. Includes all line features from Hydrography where the AV_LEGEND attribute was not equal to a value of "No Show" (AV_LEGEND <> "No Show"). This selection criterion primarily includes streams, shore and dam features; and excludes closure lines separating adjacent open water polygon features and at the limit of the data layer, apparent limits of marsh polygon areas, apparent limits of flats and sand polygon areas, and extents of coastal bays and harbors.
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Convert to GeoDatabase Feature Class format - Defined new Feature Class named Hydrography_Line; and imported the attribute definitions, loaded features and imported metadata from Hydrography_Line.shp shapefile. Spatial Reference Properties for Feature Class: Coordinate System: NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet XY Domain MinX: 100000; MaxX: 2247483.645 XY Domain MinY: 200000; MaxY: 2347483.645 Precision: 1000
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The layer retains the feature types identified by the USGS. All attributes have valid values. Values are within defined domains. The accuracy test for the HYARC_COD and HYPOLY_COD attribute values was conducted by comparing the waterbodies published on the source topographic quadrangle maps with 1:24,000-scale check plots or interactive displays of the Hydrography data on a computer graphic system. These checkplots and computer displays depicted the hydrography features in different colors based on their respective HYARC_COD and HYPOLY_COD values for comparison with the paper quadrangle maps. The HYDRO_ARC, HYDRO_POLY, AV_LEGEND, and IMS_LEGEND attribute values are based on HYARC_COD and HYPOLY_COD values. HYDRO_POLY is the English language equivalent of (decodes) the HYPOLY_COD field for polygon features. HYDRO_ARC is the English language equivalent of (decodes) the HYARC_COD field for line features. AV_LEGEND and IMS_LEGEND are broad classifications of HYPOLY_COD and HYARC_COD values for polygon and line features, respectively. Based on the HYPOLY_COD and HYARC_COD attribute values, the HYDRO_POLY, HYDRO_ARC, AV_LEGEND, and IMS_LEGEND fields were populated through table joins to lookup tables. These decode values were not manually entered. Similarly, the COASTP_COD and COASTA_COD attribute values were manually entered, and the COAST_POLY and COAST_ARC attributes that decode these values were populated through table joins to lookup tables. The COAST_POLY field decodes the COASTP_COD field for polygon features. The COAST_ARC field decodes the COASTA_COD field line features. Polygon features were manually selected and populated with STREAM_NO, LAKE_NO, HARBOR_NO, BAY_NO, and SOUND_NO attributes values that identify individually named streams, lakes, harbors, bays and sounds. Named streams represented as a series of single-line features were manually selected and attributed with the corresponding stream number values. The STREAM_NO, STREAM_NO2, LAKE_NO, LAKE_NO2, HARBOR_NO, HARBOR_NO2, BAY_NO, BAY_NO2, SOUND_NO, and SOUND_NO2 for all other line features were attributed through an automated process based on STREAM_NO, LAKE_NO, HARBOR_NO, BAY_NO and SOUND_NO attribute values of the polygon features on the left and right side of line features. For example, shoreline features for all named streams and lakes were attributed with STREAM_NO and LAKE_NO values based on values that were carefully attributed for polygon features that define the waterbody areas. Additional fields that store waterbody names decode these waterbody number values and were populated though table joins to lookup tables. For example, STREAM decodes STREAM_NO. STREAM2 decodes STREAM_NO2. LAKE decodes LAKE_NO. LAKE2 decodes LAKE_NO2. HARBOR decodes HARB0R_NO. HARBOR2 decodes HARBOR_NO2. BAY decodes BAY_NO. BAY2 decodes BAY_N02. SOUND decodes SOUND_NO. SOUND2 decodes SOUND_NO2. The NAMEDP_COD and NAMEDA_COD attribute values are based on the values of STREAM_NO, LAKE_NO, BAY_NO, HARBOR_NO, SOUND_NO, and IMS_LEGEND. NAMED_POLY and NAMED_ARC attributes decode these values and were populated though table joins to lookup tables. The NAMED_POLY field decodes the NAMEDP_COD field for polygon features. The NAMED_ARC field decodes the NAMEDA_COD field for line features. The SCALELEVEL field encodes a cartographic preference defined by the State of Connecticut, Department of Environmental Protection for displaying 1:24,000-scale features at different map scales. There are 6 Scale Levels. Each Scale Level represents a chosen set of waterbodies based on STREAM_NO, LAKE_NO, BAY_NO, HARBOR_NO, and SOUND_NO values. The ACREAGE (area in acres) field was automatically calculated for each polygon feature based on computer generated feature area in square feet. The LENGTH_MI (length in miles) field was automatically calculated for each line feature base on computer generated feature length in feet.
This data complies with United States National Map Accuracy Standards for 1:24,000 scale maps. According to this standard, not more than 10 percent of the points tested are to be in error by more than 1/50 inch (40 feet) measured on the publication scale of a USGS 7.5 minute topographic quadrangle map.
The completeness of the data reflects the USGS National Mapping Division standards for feature content of the data sources, which are the Large Scale (7.5 minute) Digital Line Graph (DLG) files available from the USGS. For Connecticut, the Large Scale DLG files used to create this layer are for the 1:24,000-scale topographic quadrangle maps published between 1969 and 1984. The layer is complete in the sense that it accurately reflects the contents of the most recently published USGS topographic quadrangle maps available at the time the State of Connecticut, Department of Environmental Protection began creating the layer. More recent quadrangle maps have been published by the USGS since 1984; however, the State of Connecticut did not incorporate this information into the layer. So compared to the most recent set of topographic quadrangle maps available today, the layer is incomplete, and substantially incomplete when compared to waterbodies present today. This data is not updated.
Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap. Polygons do not overlap other polygons. Polygons are bound by lines. Line features conform to the following topological rules. Lines are single part. There are no duplicate lines. Lines do not self overlap. Lines do not overlap other lines. Lines intersect only at nodes, and nodes anchor the ends of all lines. Lines do not overshoot or undershoot other lines they are supposed to meet and intersect. The tests of logical consistency were performed by the State of Connecticut using ESRI ArcInfo software to maintain feature topology in ArcInfo coverage format. The data is topologically clean. The ArcInfo Clean function was repeatedly used following edits to verify topology and enforce a minimum distance between vertices of 4 feet (fuzzy tolerance) and a minimum allowed overshoot length of 10 feet (dangle length).
No restrictions or legal prerequisites for using the data. The data is suitable for use at appropriate scale, and is not intended for maps printed at scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection and the U.S. Geological Survey, National Mapping Program as the source for this information. For example, include the following data source description when printing this layer on a map: Hydrography - From the Hydrography layer, compiled and published by CT DEP and USGS. Source map scale is 1:24,000.
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Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.
| Data format: | in format Shapefile, Feature Class, ArcInfo Coverage (version ArcGIS) |
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| Network links: | http://www.ct.gov/deep |
The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.
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