Natural Resources Conservation Service Montana State Office 2006 Helena, Montana Montana State Library https://ftpgeoinfo.msl.mt.gov/Data/Spatial/MSDI/HydrologicUnits/Historic/SubWatershed2006.zip https://mslservices.mt.gov/Geographic_Information/Data/DataList/datalist_Details.aspx?did={0077A7D3-F6C3-4D08-9837-410E79A12FCC} This is the Montana subwatershed layer as it existed in 2006. This dataset has been superseded by newer data and should only be used as a historical snapshot of one stage of the subwatershed deliniation process. This data set is a hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the State of Montana. This data set consists of geo-referenced digital data and associated attributes created in accordance with the "FGDC Proposal, Version 2.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 10/01/04" (https://pubs.usgs.gov/publication/tm11A34). Polygons are attributed with hydrologic unit codes for 4th level sub-basins, 5th level watersheds, 6th level subwatersheds, name, size, downstream hydrologic unit, type of watershed, non-contributing areas and flow modification. 2006 Complete -116.413582 -102.791553 49.173993 43.764268 ISO 19115 Topic Category inlandWaters geoscientificInformation HUC Hydrologic Units Hydrologic Unit Code Region Sub-region Basin Sub-basin Subbasin Watershed Watershed Boundaries boundaries Subwatershed Sub-watershed WBD Watershed Boundary Dataset 4th-code 5th-code 6th-code Montana Missouri River Columbia River South Saskatchewan River This dataset has been superseded by newer data and should only be used as a historical snapshot of one stage of the subwatershed delineation process. The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate uses described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor and not indirectly through other sources which may have changed the data in some way. These data should not be used at scales greater than 1:24,000 for the purpose of identifying hydrographic watershed boundary feature locations in Montana. The Natural Resource Conservation Service should be acknowledged as the data source in products derived from these data. The Montana Watershed Boundary Dataset is public information and may be interpreted by all organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application of the data. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions they make. The Natural Resources Conservation Service will not perform any evaluations of these maps or purposes related solely to State or local regulatory programs. Photographic or digital enlargement of these maps to scales greater than that at which they were originally delineated can result in misrepresentation of the data. If enlarged, the maps will not include the fine detail that would be appropriate for mapping at the small scale. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data from the source distributor. Montana Natural Resources Conservation Service Tom Potter mailing address

10 E Babcock, Fed Bldg Rm 443

Bozeman Montana 59715 406-587-6968 thomas.potter@mt.usda.gov Please email questions and requests. Funding for the Montana Watershed Boundary Dataset (WBD) was provided by the Natural Resources Conservation Service, the U.S. Forest Service, and the Montana Natural Resource Information System (NRIS). Representatives from all three organizations contributed a substantial amount of time and salary towards quality review of the dataset. The layer is topologically correct in that there are no overlaps or gaps between the polygons. The line feature coordinates of the accompanying hydrologic unit boundary layers are identical to the coordinates of the polygons they form boundaries of. Hydrologic units are not shown north of the International Boundary with Canada. The Lower Kootenai and Moyie River subbasins do not have watershed or subwatershed information and are not shown beyond Montana's boundary. Otherwise, the boundaries of all hydrologic units in all of the subbasins that intersect Montana are shown. The WBD was produced using Enhanced Digital Raster Graphics (DRG-Es) digital images as source map. Data completeness for DRG files reflect content of the source graphic and may therefore be reflected in the completeness and accuracy of the WBD. The map was digitized from USGS 1:24,000-scale digital raster graphic base maps, with an inherited error of /- 40 feet according to USGS National Map Accuracy Standards. Digitized line locations were held to the /- 40 foot accuracy standards by ensuring that all lines were within a 12 meter buffer of where visual interpretation put the actual boundary. Any lines outside the buffer were corrected. It is estimated that the errors detected were less than 10%. It should be noted that while general rules of hydrology were used (i.e. water flows downhill), the location of boundaries is still somewhat subjective as the 1:24,000-scale DRG-E do not always provide enough information for identifying the location of the boundaries. In these instances group consensus was used. Please refer to the methods section for more details on watershed delineation rules. As with the original DRGs, DRG-E is cast in the Universal Transverse Mercator projection and is referenced to the NAD27 datum. When the drg-es are used in the NAD83 datum the alternate world files only approximate the NAD83 by shifting the coordinates of the imagery. The total error introduced using this shift is less than 2 meters for all DRG-E imagery. National Mapping Division, U.S. Geological Survey 1940 Reston, VA U.S. Geological Survey TOPO map delineation U.S. Geological Survey digital data http://seamless.usgs.gov. 24000 online DEM map delineation USDA, Natural Resources Conservation Service 2002 remote-sensing image http://datagateway.nrcs.usda.gov/ 24000 online 2002 2003 publication date DRG-E map delineation USDA, Natural Resources Conservation Service 2005 remote-sensing image http://datagateway.nrcs.usda.gov/ 12000 online 2000 2005 ground condition DOQ map delineation USDA, Natural Resources Conservation Service 1996 vector digital data http://nris.mt.gov/nsdi/nris/shape/hd109.zip 100000 online 1996 publication date HUC5 map delineation Level 6 (12-digit) watersheds were delineated within a nested hierarchical structure using the existing Level 5 (11-digit) watershed delineation as a starting framework. The 11-digit code was reduced to 10 digits to conform to the new Federal Standards for the Delineation of Hydrologic Units Boundaries, by dropping the zero in the last position. Data fields were added to the attribute table as specified in the Federal Standards. This data had originally been compiled at a scale of 1:100,000, so the 10-digit lines were only used as a guide. HUC5 The actual delineation process involved many different people and several different methods. The U.S. Forest Service began the process by assigning the delineation task to each Forest Hydrologist or Hydrologic technician. Delineations were made on 1:24000 topological maps and often stopped at or near the forest boundary. These lines were eventually digitized on a tablet using ArcInfo. TOPO Using the Forest Service coverage as a starting point, the Natural Resources Conservation Service (NRCS) began filling in some of the private lands between the Forest Service lands. This was often done by volunteers with minimal instruction using ArcView 3x and onscreen digitizing. DRG-E 1998 In 1999, the NRCS began to take a more serious role in delineating sub-watersheds. An Arc AML was developed to create contour maps from Digital Elevation Models based on 4th and 5th code boundaries. This was overlayed with 1:100,000 hydrology. Paper maps were printed and sub-watersheds were hand drawn. These paper maps were used as a reference while digitizing onscreen using ArcView 3x and the DRG mosaics. This process was used to complete the delineation in Montana. The Forest Service, the NRCS, and the Montana Natural Resources Information System (NRIS) all contributed funding and or manpower to complete the digitizing process. DEM, DRG-E 2003 Digitizing was often done by 4th code units. These needed to be matched and joined to adjacent units and with the Forest Service data to form a statewide dataset. This was done in ArcView 3.3 in a polygon format. To avoid slivers, a false boundary was created inside of one of the units, then the true boundary was removed. This file was then merged with another that had the true boundary. A polygon was appended between the two, then split at the proper points to extend the polygons previously cut off. Finally, the false boundary was removed by unioning the features on both sides of the false boundary. DRG-E 2003 Editing and attributing were also done in ArcView 3.3. Due to the large number of digitizers involved in this project, the dataset was very inconsistent in both style and line quality. It was decided to go through the entire dataset, line by line and unit by unit to make sure the data was meeting the specifications. Fourth-code boundaries were printed to use as tally sheets. Each line was looked at on screen at a scale of 1:10,000 or larger and vertices were added, deleted, or moved as necessary. Sometimes entire watersheds were rebuilt, combined, or split. DOQs were occasionally used to help clarify line placement. Names, flows, and modifications were recorded on the tally sheets, then entered into the attribute table when a 4th code unit had completed the edit process. After the editing was complete, NRIS posted data online for public review and comment. Less then 20 comments were received and about half of those were adopted. The remaining comments were ignored because they did not follow specifications. DRG-E, DOQ 2005 The Montana dataset was matched to surrounding states. The Wyoming dataset was already certified, so the Montana data was joined to that. Most of the Idaho/Montana boundary is Continental Divide or some other major basin boundary. This line was agreed upon with Idaho. Other linework along the northwest boundary was reviewed and accepted by Idaho. The South Dakota/Montana boundary was included in the work certified by Wyoming. For the North Dakota/Montana border, Montana digitized across the border into North Dakota to complete all 4th code units that spanned the border. This was reviewed by North Dakota and agreed to changes were made. DRG-E 2005 With all edits complete, the Montana dataset was converted from a shapefile to a coverage using ArcGIS 8.3. Topology was built for both lines and polygons. The line attribute table was populated using ArcView 3.3 according to the specifications. With all data complete, the coverage was projected from UTM to geographic coordinates, then exported. 2006 State Plane Coordinate System 2500 45.000000 49.000000 -109.500000 44.250000 600000.000000 0.000000 meters North American Datum of 1983 Geodetic Reference System 80 6378137.0 298.257 SubWatershed2006 Polygon feature class FID Shapefile sequence number Shape feature geometry OBJECTID Sequence number from geodatabase version of the data HUC_8 Eight Digit Hydrologic Unit Subbasin Code A unique 8-digit code from the USGS map series "Hydrologic Unit Maps". The same number was used in every record that pertains to a subwatershed that resides within the same 8-digit sub-basin. Numbers were assigned in an upstream to downstream fashion. Where no downstream/upstream relationship could be determined numbers were assigned in a clockwise fashion. HUC_10 Ten Digit Hydrologic Unit Watershed Code This field provides a unique 10-digit code for each watershed. This same number was used in every record that pertains to a subwatershed that resides within the same 10-digit watershed. Numbers were assigned in an upstream to downstream fashion. Where no downstream/upstream relationship could be determined numbers were assigned in a clockwise fashion. HUC_12 Twelve Digit Hydrologic Unit Subwatershed Code This field provides a unique 12-digit code for each subwatershed. Numbers were assigned in an upstream to downstream fashion. Where no downstream/upstream relationship could be determined numbers were assigned in a clockwise fashion. ACRES This is the area of the 6th level unit in acres, including non-contributing areas. STATES The "States" field includes the 2-digit postal code of all state(s) that the subwatershed falls within. NCONTRB_A Non-Contributing Area Drainage areas that do not flow toward the outlet of any hydrologic unit are considered non-contributing. If a non-contributing area is on the boundary between two or more hydrologic units, the non-contributing area is associated with the hydrologic unit adjacent to the low point on the boundary. This attribute should be the total of the non-contributing areas within a hydrologic unit calculated in acres. HU_10_DS Fifth Level Downstream Hydrologic Unit Code This field has the 10-digit code of the 5th level hydrologic unit that is receiving the majority of the flow from the 5th-level watershed that the 6th level HU falls within. Outlets created by ditching or other artificial drainage were not considered for this field. If a HU flows across international borders, "CANADA" or "MEXICO" was used depending on which country the HU drains into. If an HU is a closed basin, then the term "CLOSED BASIN" was used. HU_10_NAME Fifth Level Hydrologic Unit Name A name for each 5th level hydrologic unit that relates to the major water feature within the polygon or the major water body it contributes to. This field used officially recognized names only. This field was populated by following the directions in subsection 6.3 of the Federal Standards for the Delineation of Hydrologic Unit Boundaries, "Watershed and Subwatershed Naming Protocol". The name used to attribute the watershed was used only once within a 4th level unit. HU_10_MOD Fifth Level Hydrologic Unit Modifications This field identifies any type of modifications to natural overland flow that alters the location of the hydrologic unit boundary for a 10-digit watershed. This field shows the most significant to least significant modification(s) to the watershed boundary. SC Stormwater Canal ID Irrigation Ditch IT Interbasin Transfer BC Barge Canal SD Stormwater Ditch PD Pipe Diversion CD Channel Diversion NC Non-Contributing KA Karst LE Levee NM No Modifications OC Overflow Channel DM Dam at outlet or HU boundary OT Other HU_10_TYPE Fifth Level Hydrologic Unit Type S "Standard" hydrologic unit - Any land HU with drainage flowing to a single outlet point, excluding non-contributing areas. This includes areas or small triangular wedges between adjacent HU's that remain after classic hydrologic units are delineated. Some examples include "true", "classic", "composite", and "remnant" hydrologic units. C "Closed Basin" hydrologic unit - A drainage area that is 100% non-contributing. This means all surface flow is internal, no overland flow leaves the hydrologic unit through the outlet point. F "Frontal" hydrologic unit - Areas along the coastline of lakes, oceans, bays, etc. that have more than one outlet. These HU's are predominantly land with some water areas at or near the outlet(s). W "Water" hydrologic unit - Hydrologic units that are predominantly water with adjacent land areas, ex. lake, easturies, harbors. I "Island" hydrologic unit - A hydrologic unit that is one or more islands and adjacent water out to the toe of the shore face. U "Unclassified" hydrologic unit - A hydrologic unit that can't be defined or doesn't fit into one of the types that have been listed HU_12_DS Sixth Level Downstream Hydrologic Unit Code This field was populated with the 12-digit code of the 6th level hydrologic unit that is receiving the majority of the flow from the subwatershed. Outlets created by ditching or other artificial drainage were not considered for this field. If a HU flows across international borders, "CANADA" or "MEXICO" was used depending on which country the HU drains into. If an HU is a closed basin, this field was populated with the term "CLOSED BASIN". HU_12_NAME Sixth Level Hydrologic Unit Name A name for each 6th level hydrologic unit that relates to the major water feature within the polygon or the major water body it contributes to. Officially recognized names were used in this field. This field was populated by following the directions in subsection 6.3 "Watershed and Subwatershed Naming Protocol". The name used to attribute the subwatershed was used only once within a 4th level unit. HU_12_MOD Sixth Level Hydrologic Unit Modifications This field identifies any type of modifications to natural overland flow that alters the location of the hydrologic unit boundary for a 12-digit watershed. This field shows the most significant to least significant modification(s) to the watershed boundary. SC Stormwater Canal ID Irrigation Ditch IT Interbasin Transfer BC Barge Canal SD Stormwater Ditch PD Pipe Diversion CD Channel Diversion NC Non-Contributing KA Karst LE Levee NM No Modifications OC Overflow Channel DM Dam at outlet or HU boundary OT Other HU_12_TYPE Sixth Level Hydrologic Unit Type S "Standard" hydrologic unit - Any land HU with drainage flowing to a single outlet point, excluding non-contributing areas. This includes areas or small triangular wedges between adjacent HU's that remain after classic hydrologic units are delineated. Some examples include "true", "classic", "composite", and "remnant" hydrologic units. C "Closed Basin" hydrologic unit - A drainage area that is 100% non-contributing. This means all surface flow is internal, no overland flow leaves the hydrologic unit through the outlet point. F "Frontal" hydrologic unit - Areas along the coastline of lakes, oceans, bays, etc. that have more than one outlet. These HU's are predominantly land with some water areas at or near the outlet(s). W "Water" hydrologic unit - Hydrologic units that are predominantly water with adjacent land areas, ex. lake, easturies, harbors. I "Island" hydrologic unit - A hydrologic unit that is one or more islands and adjacent water out to the toe of the shore face. U "Unclassified" hydrologic unit - A hydrologic unit that can't be defined or doesn't fit into one of the types that have been listed SHAPE_area Area of polygon in square meters. SHAPE_len Length of the feature perimeter in meters. Montana State Library mailing address

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