Aquifer Protection Areas is a 1:24,000-scale, polygon feature-based layer that includes all Preliminary (Level B) and Final (Level A) Aquifer Protection Areas approved by the Connecticut Department of Energy and Environmental Protection (DEEP). These areas represent the land area contributing ground water to active public water supply wells or well fields that serve more than 1000 people that are set in sand and gravel aquifers (stratified drift deposits). These areas are commonly referred to as wellhead protection areas. The Aquifer Protection Areas were delineated by the individual water utilities owning the well fields and submitted to the DEEP for approval. The preliminary mapping provides a general estimate of the area contributing ground water to the well field. The final mapping is based on extensive, site-specific, detailed modeling of the ground water flow system. As the final mapping is completed it replaces the preliminary mapping. The layer is based on information collected and compiled from 1991 to the present. The layer depicts current conditions. Attribute information is comprised of codes to uniquely identify individual features, encode the aquifer protection area type and status, and cartographically represent area features on a map. Data is compiled at 1:24,000 scale. This data is updated as final mapping becomes available.
For additional information, refer to the Aquifer Protection Program at the Connecticut Department of Energy and Environmental Protection found on website http://www.ct.gov/dep/aquiferprotection
publication dates
Aquifer Protection Areas represented as polygons. Each polygon is a wellfield. (Source: State of Connecticut, Department of Environmental Protection)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
ArcView Legend. Text field for symbolizing hydrography line feature types on a map. (Source: State of Connecticut, Department of Energy and Environmental Protection)
| Value | Definition |
|---|---|
| Final | Detailed mapping (Level A delineation) of wellfield that follows the preliminary mapping. |
| Preliminary | The first mapping (Level B delineation) of a wellfield as a general estimate of critical areas. |
Regulated status of Aquifer Protection Area. Final areas are regulated. Preliminary areas are expected to be regulated. (Source: State of Connecticut, Department of Energy and Environmental Protection)
| Value | Definition |
|---|---|
| Regulated | Regulated status of Aquifer Protection Area |
Identification number for each aquifer protection area. (Source: State of Connecticut, Department of Energy and Environmental Protection)
Identification number of the water company system that the aquifer protection area wellfield belongs to. Superceded by DPHSYSID. Field remains for backward compatibility. (Source: State of Connecticut, Department of Public Health, Water Supplies Section)
Department of Public Health identification number of the water company system that the aquifer protection area wellfield belongs to. (Source: State of Connecticut, Department of Public Health, Water Supplies Section)
Name of Aquifer Protection Area wellfield (Source: State of Connecticut, Department of Energy and Environmental Protection)
| Value | Definition |
|---|---|
| Varies by the aquifer protection area | [not provided] |
Name of water company that owns the Aquifer Protection Area (Source: State of Connecticut, Department of Energy and Environmental Protection)
| Value | Definition |
|---|---|
| Varies by aquifer protection area | [not provided] |
Any portion of a Final Aquifer Protection Area that has been adopted at the local level by the town in which it is located and for which land use regulations are in place. (Source: State of Connecticut, Department of Energy and Environmental Protection)
| Value | Definition |
|---|---|
| Yes | This portion of a Final Aquifer Protection Area has been adopted. |
| No | This portion of a Final Aquifer Protection Area has not yet been adopted. |
| NA | Not Applicable, this is a Preliminary Aquifer Protection Area. |
Includes Aquifer Protection Area features such as "Final" and "Preliminary". Information encoded about these features includes APA_NO, APASTATUS, APANAME, UTILITY and SYSTEMID information and standard cartographic symbology classification schemes. Use the APA_NO and APANAME to uniquely identify features. Use the AV_LEGEND attribute to symbolize features by type on a map. Use the APANAME and AV_LEGEND to label features on a map. To define a layer that only includes Final area features, query APA features for AV_LEGEND value equal to "Final". To define a layer that only includes Preliminary area features, query APA features for AV_LEGEND value equal to "Preliminary". APASTATUS contains "Regulated" and serves as a flag to during processing to separate those Aquifer Protection Areas that belong in the Aquifer Protection Area datalayer from the other Non - Aquifer Protection Areas that are maintained. If AV_LEGEND is "Final" then it is a regulated area. If AV_LEGEND is "Preliminary" then the area is expected to be regulated when the Final Aquifer Protection Area is delineated and replaces the Preliminary area.
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Aquifer Protection Areas is 1:24,000-scale data. It depicts the location of regulated aquifer protection areas. The final mapping will define the regulatory boundaries for the land use regulations. Land use controls will be imposed in those areas to minimize the potential for contamination of the well field. Use this layer with other 1:24,000-scale map data such as base map data, high risk activities and surficial material. Not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)
This data source refers to the original manuscripts of Preliminary (Level B) Aquifer Protection Areas as mapped by the water companies for their well fields including the water supply wells. Water companies are required to map, using methods specified in the Level B mapping guidelines, the critical portions of the aquifer which provide water to the well fields. Preliminary mapping provides a general estimate of the critical areas based on limited data about pumping rates of the well(s) and the aquifer materials. The mapping was provided at 1:24,000 scale on USGS 7.5 minute topographic maps.
This data source refers to the original manuscripts of Final (Level A) Aquifer Protection Areas as mapped by the water companies for their well fields including the water supply wells. Water companies are required to map, using methods specified in mapping regulations (see 22a-3546-1 of the Regulations of Connecticut State Agencies), the critical portions of the aquifer which provide water to the well fields. The mapping is conducted by the water companies using extensive, site-specific data and ground-water modeling to determine the Final (Level A) mapping area. The mapping was provided at 1:24,000 scale on USGS 7.5 minute topographic maps or on disc in digital form.
This data source refers to the all of the Preliminary (Level B) aquifer protection area delineations combined into a 1:24,000-scale, statewide, digital datalayer. The Preliminary Master coverage of aquifer protection areas is maintained separately from the Final Master coverage for ease in editing. When new Final aquifer protection area mapping is added to the Final Master coverage, its counterpart in the Preliminary Master coverage is given a designation of "Replaced" in the APASTATUS field. The APASTATUS field domain is "Regulated", "Level B Only", "Replaced", "Future", "Abandoned" and "RI Wellfld". Preliminary aquifer protection areas are not actually regulated but the APASTATUS field identifies the areas expected to be regulated. Preliminary Master is in ArcInfo coverage format.
This data source refers to the all of the Final (Level A) aquifer protection area delineations combined into into a 1:24,000-scale, statewide, digital datalayer. The Final Master coverage of aquifer protection areas is maintained separately from the Preliminary Master coverage for ease in incorporating new Final aquifer protection area mapping as it becomes available. Final Master is in ArcInfo coverage format.
This data source refers to a coverage format datalayer of all Aquifer Protection Areas created by combining the Final Master coverage aquifer protection areas with aquifer protection areas selected (APASTATUS = "Regulated") from the Preliminary Master coverage. The preliminary aquifer protection areas are not actually regulated but are identified as areas expected to be regulated when the Final aquifer protection area is delineated. APA coverage is in ArcInfo coverage format.
This data source refers to a coverage format datalayer of non-regulated Aquifer Protection Areas. These are the areas selected from the Preliminary Master coverage that are not designated as "Regulated" in the APASTATUS field. They are the areas that are designated "Level B Only", "Replaced", "Future", "Abandoned" or "RI Wellfld". Note that Preliminary areas are not actrually regulated areas, but placeholders for the final areas that will be regulated. APANON coverage is in ArcInfo coverage format.
This data source refers to a shapefile format datalayer of regulated Aquifer Protection Areas created from the Aquifer Protection Areas coverage. They are comprised of the Final Master coverage aquifer protection areas and the regulated aquifer protection areas selected from the Preliminary Master coverage. APA.shp is in Shapefile format.
This data source refers to a shapefile format datalayer of non-regulated Aquifer Protection Areas created from the Non-regulated Aquifer Protection Areas coverage. These are the areas selected from the Preliminary Master coverage that are not designated as "Regulated" in the APASTATUS field. They are the areas that are "Level B Only", "Replaced", "Future", "Abandoned" or "RI Wellfld". APANON.shp is in Shapefile format.
This data source refers to a geodatabase format datalayer of all Aquifer Protection Areas created by converting all features of Source 4 - Final Master and all features of Source 3 - Preliminary Master coverages to geodatabase format and then combining the Final Master and the Preliminary Master geodatabase format aquifer protection areas into a single APAMaster. The preliminary aquifer protection areas are not actually regulated but are identified as areas expected to be regulated when the Final aquifer protection area is delineated. APAMaster is in ArcGIS geodatabase format.
This data source refers to a geodatabase format datalayer of regulated Aquifer Protection Areas. They are comprised of regulated aquifer protection areas, final and preliminary, selected from the APAMaster.
This data source refers to a shapefile format datalayer of regulated Aquifer Protection Areas. They are comprised of regulated aquifer protection areas, final and preliminary, selected from the APAMaster.
Feature digitizing and attribution (digitizing tablet method) - Using ESRI ArcInfo software, features were digitized by registering the source map to the digitizing tablet and using the crosshairs of the digitizer's mouse to manually capture the geometry (location) of features drafted on the map. Water utility companies drafted their source data onto USGS 7.5 minute topographic quadrangle maps. The corners of the quadrangle maps are used as registration points and are depicted on the source map. The source map was registered to the digitizing tablet by digitizing (entering) the locations of four quadrangle corner registration points shown on the map. ArcInfo software compared the values of the digitized coordinates with the actual (true) values for the quadrangle corner (tic) features. The Root Mean Square (RMS) error generated by the ArcInfo software indicated the amount of error involved in transforming coordinates from the registered map to the digital layer. RMS errors higher than 0.004 were not acceptable and required re-registering the source map by digitizing the tic locations again. With a correct registration, individual features were manually digitized off the source map and assigned APA_NO values. Where necessary, additional minor corrections (edits) to feature geometry were manually digitized on the screen (heads-up digitizing) at display scales greater than 1:24,000. Where appropriate, sections of the aquifer protection area outline were swapped for coincident line features from existing base datalayers such as drainage basins, hyrdography and roads and trails. Features were assigned APA_NO attribute values based on information in the Aquifer Protection Program database. Feature location and attribute accuracy was visually checked and inspected by symbolizing and labeling features according to attribute value on the computer screen and on hard copy paper maps, and comparing this information to the orginal source data. These check plot maps were printed at the same scale as the source maps in order to visually inspect digitizing quality and the assignment of attribute values. After the data was verified by these methods the individual Preliminary (Level B) digital files were combined into the Preliminary Master coverage. Region.apa is used to store the features. The individual Final (Level A) digital files were combined into the Final Master coverage. Region.apa is used to store the features. As new Final Aquifer Protection Areas are delineated they are added to the Final Master and the APAStatus attribute value of the corresponding area in the Preliminary Master is changed to "Replaced".
Combining of the Final and Preliminary Aquifer Protection Areas into new datalayers - The macro, apalayer.aml, is run to select all features from Final Master and features with APASTATUS = "Regulated" from Preliminary Master and combine them into the APA coverage. Because the Preliminary Aquifer Protection Areas overlap, regions are used to store and maintain the features. Region.apa contains both Preliminary and Final areas and they can be identified and separated by the attribute AV_LEGEND. All Preliminary areas with an APASTATUS other than "Regulated" are combined into the coverage APANON. Region.nonap contains all these other areas and they can be identified and separated by the attribute APASTATUS. Updates or changes are made to the master coverages and the APA and APANON coverages are regenerated.
Datum conversion - Using ESRI ArcInfo software, the Preliminary Master and Final Master layers were 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.
Attribute enhancements - Any attribute values stored in upper case were changed from storing abbreviated values in upper case to full length values in both upper and lower case.
Export to Shapefile format - Converted region.apa data, based on polygon features, from an ArcInfo coverage named APA to a Shapefile named APA.shp. Excluded the AREA, PERIMETER, APA#, and APA-ID attributes from the Shapefile because their values are only maintained by ArcInfo software with spatial data that is ArcInfo coverage format. Converted region.nonap data, based on polygon features, from an ArcInfo coverage named APANON to a Shapefile named APANON.shp. Excluded the AREA, PERIMETER, APANON#, and APANON-ID attributes from the Shapefile because their values are only maintained by ArcInfo software with spatial data that is ArcInfo coverage format. When new coverages are generated, after alterations to the master coverages, new shapefiles are generated.
Convert to GeoDatabase Feature Class format - Aquifer Protection Area datalayers were converted to geodatabase format feature classes according to the following steps: Defined new Feature Class, imported the spatial reference, defined or imported the attribute definitions, loaded features from coverage, imported metadata from shapefile, edited metadata. The Source 3 - Preliminary Master was converted to temporary polygon feature class Preliminary Master. The Source 4 - Final Master was converted to temporary polygon feature class Final Master. Preliminary Master and Final Master were combined into polygon feature class APAMaster. The model for storing the master dataset was changed for several reasons. The geodatabase format (unlike the coverage format) allows discrete overlapping polygons, no internal structure for wellfield is used (earlier internal structure was never used so it was eliminated), it is not necessary to differentiate between replaced APA types. Spatial Reference Properties for Feature Classes: 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
Create geodatabase regulated APA - Select regulated aquifer protection areas from Source 9 - Geodatabase APAMaster to produce Source 10 - Geodatabase Aquifer Protection Area.
Create shapefile regulated APA - Select regulated aquifer protection areas from Source 9 - Geodatabase APAMaster to produce Source 11 - Shapefile Aquifer Protection Area.
Additional Information is integrated into the Aquifer Protection Area polygon features and attributes. The Final Regulated Aquifer Protection Areas are subdivided into an adopted and not yet adopted category. Any portion of a Final Regulated Aquifer Protection Area that has been adopted at the local level by the town in which it is located and for which land use regulations are now in place is a polygon feature. To identify the Final Adopted Areas, use the Adopted = "Yes" attributes to select the polygon features. Create Aquifer Protection Area: Select final regulated aquifer protection areas from Source 9 - Geodatabase APAMaster to form a temporary Final Regulated Aquifer Protection Area datalayer. Perform identity overlay between the Final polygon features and the polygon features of the DEP town datalayer to divide the Final Aquifer Protection Areas by town. Join a table that contains aquifer protection area numbers associated by town and whether or not adopted. Dissolve the temporary Final Aquifer Protection Area datalayer on the aquifer protection area number and the adopted attribute. Select Preliminary Aquifer Protection Areas from Source 9 - Geodatabase APAMaster and add to the Final Regulated Aquifer Protection Area to produce Source 10 - Geodatabase Aquifer_Protection_Area.
Export all adopted aquifer protection area polygon features from Source 10 - Geodatabase Aquifer_Protection_Area to produce Source 11 - Shapefile Aquifer_Protection_Area.shp.
Metadata imported.
The Aquifer Protecton Areas layer retains the feature types and information identified by the State of Connecticut, Department of Energy and Environmental Protection and obtained from the Aquifer Protection Program database information. All attributes have valid values. Values are within defined domains. The accuracy test for the APA_NO attribute values was conducted by comparing the aquifer protection area identification number information presented in the source data with 1:24,000-scale check plots or interactive displays of the data on a computer graphic system as each Aquifer Protection Area was digitized. These check plot maps and computer displays depicted and labeled the Aquifer Protecton Areas features in based on APA_NO values for comparison with the original data source. AV_LEGEND is a broad classification of Aquifer Protecton Areas features. AV_LEGEND was assigned from the parent data sources. APASTATUS, APA_NAME, UTILITY and SYSTEM-ID fields were populated by joining to lookup data tables with APA_NO as the relate key field.
Feature locations are a composite of underlaying source locations. Features were digitzed from features drawn on 1:24,000 scale USGS 7.5 minute topographic quadrangle maps. Feature locations intended to be coincident were interpolated from the transporation features, surface water features and elevation features depicted on USGS 7.5 minute topographic quadrangle maps. The horizontal positional accuracy of this data is no better than the United States National Map Accuracy Standards for 1:24,000 scale maps. According to this standard, not more than 10 percent of the locations 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. Feature locations intended to be coincident were interpolated from the DEEP drainage basin features. The horizontal accuracy of other feature locations is not known.
The completeness of the data reflects the feature content of the data sources, which include the water companies' original mapping and the 1:24,000-scale base map and drainage basin data from DEP. The Aquifer Protecton Areas layer is complete in the sense that it accurately reflects the contents of the preliminary and final aquifer protection area delineation information available at the time the State of Connecticut, Department of Environmental Protection created the layer. This data is 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. Polygon features are grouped into regions in subclass region.apa. 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). After format conversion to geodatabase feature class the following changes in topological rules occurred. Polygons can overlap other polygons. The regions subclass, region.apa, was discontinued.
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 Energy and Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Energy and 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 Energy and 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 Energy and Environmental Protection as the source for this information. For example, include the following data source description when printing this layer on a map: Aquifer Protection Area - From the Aquifer Protection Area layer, compiled and published by the CT DEEP. Source map scale is 1:24,000.
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| Data format: | in format Shapefile, Feature Class (version ArcGIS) Size: 0.406 |
|---|---|
| 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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