US EPA Initially 20040401 (see Maintenance_and_Update_Frequency) vector digital data GRTS Locational Data 1 Washington, DC US EPA http://www.epa.gov/waters/data/downloads.html GRTS locational data for nonpoint source projects. GRTS locations are coded onto route.drain (Transport and Coastline Reach) feature of NHD to create Point Events and Linear Events. GRTS locations are coded onto region.rch (Waterbody Reach) feature of NHD to create NHD Waterbody Shapefiles. In addition to NHD reach indexed data there may also be custom shapefiles (point, line, or polygon) that are not associated with NHD and are in an EPA standard format that is compatible with EPA's Reach Address Database. These custom shapefiles are used to represent GRTS locations that are not represented well in NHD. To be used to identify the spatial extent of the nonpoint source project locations. These waters can be linked to the GRTS locations stored in the EPA Grant Reporting Tracking System (GRTS) database for query and display. The ENTITY_ID field in the event table/shapefile can be linked to the Grant Number_Project Number_Drainage Area Number in EPA's GRTS database. NHD Vintage: NHD (Flow-validated, Re-leveled) -- Current as of June, 2002 (compatible with EPA Reach Address Database Version 2.0) 2004 (varies between and sometimes within jurisdictions; see Maintenance_and_Update_Frequency) see Maintenance_and_Update_Frequency In work Annually -180 -60 80 0 None GRTS Grant Reporting Tracking System Nonpoint source Metadata Service Theme Categories environment inlandWaters None US National None When using this data in a spatial query, errors in determining the overlap can occur. The errors can be grouped as follows: (1) False Positives occur when the locational information is either incorrect or not of sufficient quality to determine its exact location. (2) False Negatives occur when locational information is missing or not available. (3) In addition to the entity locational information, errors, although few, may also exist in the spatial network of rivers, streams, and other waterbodies that comprise the National Hydrography Dataset (NHD) jointly maintained by USGS and USEPA. Errors in the NHD may contribute both to false positive and false negative readings. Don Kunkoski US EPA Headquarters mailing address

1200 Pennsylvania Avenue, NW

Washington DC 20460 301-694-7329 Kunkoski.Don@epamail.epa.gov None Unclassified None ArcView 3.2 (used in conjunction with the Reach Indexing Tool (RIT) and the National Hydrography Dataset (NHD) - NHD (Flow-validated, Re-leveled) -- Current as of June, 2002 (compatible with EPA Reach Address Database Version 2.0), and/or EPA's Web-Based Reach Indexing Tool (WebRIT). Chain-node topology present Statements of horizontal positional accuracy are based on accuracy statements made for USGS topographic quadrangle maps. These maps were compiled to meet National Map Accuracy Standards. For horizontal accuracy, this standard is met if at least 90 percent of points tested are within 0.02 inch (at map scale) of their true positions. Additional offsets to positions may have been introduced where there are many features to improve the legibility of map symbols. In addition, the digitizing of maps is estimated to contain a horizontal positional error of less than or equal to 0.003-inch standard error (at map scale) in the two component directions relative to the source maps. Visual comparison between the map graphic (including digital scans of the graphic) and plots or digital displays of points, lines, and areas is used to assess the positional accuracy of digital data. Linear features of the same type along the adjoining edges of data sets are aligned if they are within a 0.02-inch tolerance (at map scale). To align the features, the midpoint between the end of the corresponding features is computed, and the ends of features are moved to this point. Features outside the tolerance are not moved; instead, a feature of the type connector was added to join the features. For more information, see the National Hydrography Dataset Concepts and Contents document (February 2000) available at <http://nhd.usgs.gov/chapter1/index.html>. Statements of vertical positional accuracy for elevation of water surfaces are based on accuracy statements made for USGS topographic quadrangle maps. These maps were compiled to meet National Map Accuracy Standards. For vertical accuracy, this standard is met if at least 90 percent of well-defined points tested are within one-half contour interval of the correct value. Elevations of water surface printed on the published map meet this standard; the contour intervals of the maps vary. These elevations were transcribed into the digital data; the accuracy of this transcription was checked by visual comparison between the data and the map. For more information, see the National Hydrography Dataset Concepts and Contents document (February 2000) available at <http://nhd.usgs.gov/chapter1/index.html>. Each organization (state, county, etc) entered the location of each GRTS nonpoint source project using the Web-Based Reach Indexing Tool (WebRIT). Using the WebRIT NHD event tables were created. Event identifiers were populated with the GRTS ID (Grant Number_Project Number_Drainage Area Number) that match the GRTS projects in EPA's Grant Reporting Tracking System. Initially 20040401 (see Maintenance_and_Update_Frequency) Vector 1 1 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137 meters 298.257222101 Point and linear event themes, NHD waterbody shapefiles, and Custom Shapes (point, line, and polygon shapefiles that are not associated with NHD). Each point event theme applies to a point along a section of the National Hydrography Dataset (NHD), which is a comprehensive set of digital spatial data that contains information about surface water features such as lakes, ponds, streams, rivers, springs and wells. Line event themes apply to linear positions along sections of the NHD. Each waterbody theme applies to whole or portions of NHD waterbody reaches. All other point, line, and polygon shapefiles represent geometries that do not fall on the NHD network of streams/coastline and lakes/ponds. EPA's Web-Based Reach Indexing Tool (WebRIT) and EPA's National Hydrography Dataset Reach Indexing Tool (NHD-RIT). FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. EVENT_ID Unique ID for an event created based on date and time when the event was created, and a sequential number to provide uniqueness for events created at the same time. System created number (WebRIT or NHD-RIT) 2000010100000100001 9999123124000099999 P_MEAS Specifies the location of the point along a route. This field is only used for point event themes. EPA's WebRIT or NHD-RIT 0 200 EOFFSET Offset distance of event from associated NHD route reach location. This field is only used for point and linear event themes. User input 0 999999 DUU_ID Unique identifier of the digital update unit in the NHD database. This field is only used for point and linear events and NHD waterbody shapefiles. NHD 0000000001 9999999999 RCH_CODE Numeric code that uniquely identifies a reach in NHD, consisting of two parts: the first eight digits are the hydrologic unit code of the cataloging unit in which the reach is located; the last six digits are a sequentially, arbitrarily-assigned number. This field is only used for point and linear events and NHD waterbody shapefiles. NHD NHD Reach codes USGS NHD RCH_DATE Date that the reach code (Rch_code) was assigned, displayed as YYYYMMDD. This field is only used for point and linear events and NHD waterbody shapefiles. NHD 19970101 99991231 ATTR_PRG Indicates the attribute type or program being indexed. WebRIT or NHD-RIT Alphanumeric ASCII ATTR_VAL Value associated with the attribute program in the field Attr_prg. User Input Alphanumeric ASCII ENTITY_ID Identifier used to aggregate reaches into homogenous units. It is also used to link the event table to external data sources. EPA's Grant Reporting Tracking System Alphanumeric ASCII STATE State abbreviation according to the FIPS standard. The state used in this field is the geographic area (state) that the event is located in. User input Federal Information Processing Standard Two digit FIPS state code (character). META_ID Link to the metadata table System created number (WebRIT or NHD-RIT) Alphanumeric ASCII F_MEAS Specifies the start point of the event along a route. This field is only used for linear events. EPA's WebRIT or NHD-RIT 0 200 T_MEAS Specifies to end point of the event along a route. This field is only used for linear events. EPA's WebRIT or NHD-RIT 0 200 METERS Length along the reach (in meters). This field is only used for linear events. EPA's WebRIT or EPA's NHD-RIT 0 40,000,000 SQ_KM Area of the waterbody shape (in square kilometers). This field is only used for NHD waterbody shapefiles. EPA's WebRIT or EPA's NHD-RIT 0 40,000,000 The WebRIT online help and tutorial can be found at <http://www.epa.gov/waters/webrit/training.htm>. The NHD Reach Indexing Tool Users's Guide - October 2002 can be found at <http://www.epa.gov/waters/georef/UserGuide.pdf> Don Kunkoski US EPA Headquarters mailing address

1200 Pennsylvania Avenue, NW

Washington DC 20460 301-694-7329 Kunkoski.Don@epamail.epa.gov Downloadable Data 20040608 Don Kunkoski US EPA Headquarters mailing address

1200 Pennsylvania Avenue, NW

Washington DC 20460 301-694-7329 Kunkoski.Don@epamail.epa.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile 200411021257270020041102