This is a coverage of the boundaries and codes used for the
U.S. Geological Survey's National Water-Quality Assessment (NAWQA)
Program Study-Unit investigations in the conterminous United
States, excluding the High Plains Regional Ground-Water Study.
The data set represents the areas studied during the first decade
of the NAWQA Program, from 1991-2001 ("cycle 1").
The National Water-Quality Assessment Program is a primary source for long-term, nationwide information on the quality of streams, ground water, and aquatic ecosystems (Gilliom and others, 2001). The goals of NAWQA are to assess the status and trends in the quality of the Nation's ground- and surface-water resources and to provide a sound understanding of the natural and human factors that affect the quality of these resources (Leahy and others, 1990). Study Units are defined by major river basins and aquifers across the Nation (Gilliom and others, 2001). This coverage contains the boundaries for the Study Units within the conterminous United States (excluding the High Plains Regional Ground Water-Study) that were defined during cycle 1 of NAWQA. During cycle 1 of NAWQA, 51 studies actually were undertaken (49 in the conterminous U.S. and one each in Alaska and Hawaii), and 8 were not scheduled. This coverage depicts 57 Study Units: 49 actually studied and 8 not scheduled. The coverage also includes the name, starting date, and NAWQA standard abbreviation of each Study Unit plus various codes to help display the data. The second cycle of NAWQA (2001-2012) will adjust its scope to 42 of these important river basins and aquifer systems to accommodate budget reductions. The second cycle of investigations began in 14 Study Units in 2001. Although the boundaries of most Study Units remain the same in cycle 2, the boundaries and codes for cycle 2 Study Units are maintained in a separate data set (NAWQACYC2). This data set is used primarily to display the location of NAWQA Study Units and for analysis of data at the national scale. It is not recommended for either local or regional analysis due to the small scale of most of the features. For use with the GEOSTAC database, this data set has been compiled in order to simplify pesticide risk assessment and to provide a common data set for interested parties.
Originally, Study-Unit boundaries in this coverage were composed of 1:2,000,000-scale hydrologic unit boundaries (Allord, 1992) and state boundaries (Negri, 1994). As the NAWQA project progressed and Study-Unit Investigations got underway, many Study-Unit boundaries were modified. In addition, Study Units enhanced their boundary coverages with features at higher resolutions. As these modifications were made, Study Units submitted their new boundary coverages to National Synthesis teams, who are responsible for summarizing the results from all of the Study Units, and the changes were incorporated into this coverage. As a result, this coverage is composed of linear features at various scales (for example, 1:100,000, 1:250,000), but the majority remain at the 1:2,000,000 scale. The original version of this coverage was generated by the USGS Cartographic and Publishing Program (CAPP) in Madison, Wisconsin, in the fall of 1991. The procedures used to create this coverage are described below. Each NAWQA Study Unit was asked for a description of their boundary definition. Once this information was gathered, CAPP created the coverage by extracting digital features from the 1:2,000,000 Hydrologic Unit boundaries coverage and the 1:2,000,000 state boundaries coverage. Since the majority of Study-Unit boundaries are defined from hydrologic unit boundaries, most of the features were directly copied from the Hydrologic Units coverage. An exception to this was the boundary defining the Georgia-Florida Coastal Plain Study Unit where the northern boundary was defined by the northern edge of the Floridan Aquifer. To incorporate this boundary into the coverage, the aquifer boundary was digitized from the U.S. Geological Survey's "Ground-Water Atlas of the United States", HA-730 (G) (Miller, 1990). In November 1991, responsibility for maintaining the coverage was transferred to NAWQA's National Synthesis staff. Major milestones in the development of the coverage and various revisions to the coverage are listed under the Lineage section. The coverage is reviewed by one of the NAWQA National Synthesis GIS staff members prior to release. Alaska (Cook Inlet) and Hawaii (Oahu) NAWQA Study-Unit boundaries are maintained in separate data sets. The High Plains Regional Ground-Water Study boundary is in a separate data set. Cook, Oahu, and High Plains study boundaries should be used with this data set to give the full picture of NAWQA Study Units nationwide. References Allord, G.J., 1992, 1:2,000,000 Hydrologic Unit map of the conterminous United States, Version 1.1.2. Available through the internet at <URL:http://water.usgs.gov/lookup/getmeta?huc2m>. Gilliom, R.J., Alley, W.M., and Gurtz, M.E., 1995, Design of the National Water-Quality Assessment Program--Occurrence and distribution of water-quality conditions: U.S. Geological Survey Circular 1112, U.S. Geological Survey, Sacramento, California, 33 p. Available through the internet at <URL:http://water.usgs.gov/pubs/circ/circ1112/>. Gilliom, R.J., Hamilton, P.A., and Miller, T.L., 2001, The National Water-Quality Assessment Program--Entering a new decade of investigations: U.S. Geological Survey Fact Sheet 071-01. Available through the internet at <URL:http://water.usgs.gov/pubs/FS/fs-071-01/pdf/fs07101.pdf> Leahy, P.P., Rosenshein, J.S., and Knopman, D.S., 1990, Implementation plan for the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 90-174. U.S. Geological Survey, Reston, Virginia, 10 p. Leahy, P.P. and Thompson, T.H., 1994, National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 94-70, 4 p. Available through the internet at <URL:http://water.usgs.gov/nawqa/NAWQA.OFR94-70.html>. Miller, James A., 1990, Ground water atlas of the United States-Segment 6, Alabama, Florida, Georgia, and South Carolina: U.S. Geological Survey Hydrologic Atlas Hydrologic Investigations Atlas-730-G, 28 p. Information about the Ground Water Atlas is available at <URL:http://capp.water.usgs.gov/gwa/index.html>. Nebert, Douglas D. and Steeves, P.A., 1994, Digital map file of hydrologic unit boundaries for the conterminous United States processed from 1:100,000- and 1:250,000-scale U.S. Geological Survey Geographic Information Retrieval and Analysis System (GIRAS) data files. U.S. Geological Survey Open File Report 94-326. Available on the internet through <URL:http://water.usgs.gov/lookup/getmeta?huc250k>. Negri, M., 1994, 1:2,000,000 Digital map of state boundaries of the conterminous United States. Available through the internet at <URL:http://water.usgs.gov/lookup/getspatial?states2m>.
Current as of publication date.
Accuracy is good at 1:2,000,000 or smaller in most cases. The Study-Unit source maps come from various sources and scales.
12201 Sunrise Valley Drive, MS-413
Please contact through email
See Entity_Attribute_Information
Where present, is described with each attribute defined in the Entity and Attribute Section.
The data set was checked for topological consistency using the Arc/INFO commands BUILD and LABELERRORS.
The data set contains NAWQA boundaries (excluding HPGW) for the conterminous United States.
This layer provided 1:2,000,000 hydrologic unit boundaries that served as an initial source of the NAWQA Study Unit boundaries.
This layer provided the northern edge of the Floridan Aquifer, which formed part of the boundary of the Georgia-Florida Coastal Plain NAWQA.
This layer contributed some higher resolution hydrologic unit boundaries.
This layer contributed state boundaries.
Version 1.0 - Received NAWQA coverage from Greg Allord, Madison, WI.
Version 1.1 - Added item USBND to .AAT for plotting purposes only.
Version 1.2 - Updated three Study-Unit boundaries: 1) Modified Red River of the North to include portion in Canada. A file containing latitude/longitude coordinates was used in determining the new northern boundary. 2) Replaced Ozark Plateau Study Unit with exported coverage from Ozark Plateau Study Unit staff. 3) Excluded the area that defines HUC 02030102 from Hudson River Basin Study Unit.
Version 1.3 - Updated two Study-Unit boundaries: 1) Updated Apalachicola-Chattahoochee-Flint Basin with an exported coverage from ACFB Study Unit. (Source scale: 1:250,000.) 2) Modified Nevada Basin and Range (southern portion) to exclude most of eastern area defined by HUC 15010005.
Version 1.4 - Added item CANADA to .AAT and to .PAT for plotting purposes only.
Version 1.5 - Updated Study-Unit boundaries: 1) Updated Lower Susquehanna Study-Unit boundary. It now includes portion of the area defined by HUC 02060002. 2) Modified northeast section of the Willamette Study Unit with an exported coverage from Willamette Study Unit. 3) Replaced Apalachicola-Chattahoochee-Flint Basin boundary with an exported coverage. 4) Modified labels for Long Island and New Jersey Coastal Plain Study Unit.
Version 1.6 - Replaced Ozark Plateau Study-Unit boundary with an exported coverage.
Version 1.7 - Modified two Study-Unit boundaries: 1) Eliminated area defined by HUC 05120209 from White River Basin Study Unit. 2) Replaced Central Oklahoma Study-Unit boundary with an exported coverage from Central Oklahoma Study Unit.
Version 1.8 - Replaced Ozark Plateau Study-Unit boundary with an exported coverage.
Version 1.9 - Deleted HUC 18040003 from San Joaquin-Tulare Basin Study Unit.
Version 2.0 - Various changes to Study-Unit boundaries have been incorporated into the coverage.
Version 3.0 - Study Units supplied new boundaries for Southern Florida, Great Salt Lake, Upper Colorado, and Sacramento. Name of Puget Sound Basin and Lower Illinois River Basin Study Units were changed.
Version 3.1 - HUCs 06020001, 06020002, 06020003 were added to the Upper Tennessee River Basin Study Unit. We used the 1:2,000,000 HUC boundaries except where they coincided with the Apalachicola-Chattahoochee-Flint Basin. Along the ACFB, we used the ACFB boundary originally in the coverage.
Version 3.2 - The entire Lower Susquehanna Study-Unit boundary was replaced by a coverage supplied by Steve Siwiec. (The most noticeable change occurred in the southeastern corner of the Study Unit.) As a result, the boundaries for the adjacent Study Units adjacent (Potomac, Allegheny-Monongahela and Delaware River) were slightly modified.
Version 3.3 - Expanded Lake Erie-Lake St. Clair to include HUCs 4090001-5 and 4120101-3 per Dennis Finnegan.
Version 3.3 - Expanded South Central Texas to include surface water drainage to the coast using coverage from Jim Bisese.
Version 3.3 - Minor change to Central Arizona Basins boundary. New boundary from Julie Rees.
Version 3.3 - Replaced San Joaquin-Tulare Study-Unit boundary with a coverage provided by JoAnn Gronberg and the Sacramento Study-Unit boundary with a coverage from Donna Knifong. The portion of the boundary shared with Nevada Basin and Range was NOT replaced. The difference between the new boundaries and the old boundaries is very small. The new boundaries are at the 1:250,000-scale. Part of the Sacramento Delta was modified to match the Sacramento Study-Unit boundary.
Version 3.3 - Changed abbreviation for Northern New England Basins from NHME to NNEB.
Version 3.3 - Minor change to Allegheny-Monongahela Study-Unit boundary using enhanced boundary from Mary Mulkerrin. ALMN's boundary overrode Potomac's and Lower Susquehanna's western boundary.
Version 3.3 - Replaced Upper Tennessee and Lower Tennessee boundaries with coverage from Joe Connell. Lower Tennessee expanded out a little into Upper Tennessee.
Version 3.3 - Northwestern portion of Upper Mississippi has expanded out to Red River of the North. Paul Hanson provided a new Upper Mississippi boundary coverage for update. The boundary common with Red River of the North has been replaced with the new Upper Mississippi boundary.
Version 3.3 - Enhanced Red River of the North boundary (EXCEPT portion common with Upper Mississippi) with coverage from Dave Lorenz.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Expanded former Chicot-Evangeline to include Lake Pontchartrain with coverage from John Lovelace. The new Study Unit is called Acadian-Pontchartrain and the abbreviation is ACAD.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Expanded Mobile River and Tributaries with coverage from Darrell Lambet.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Edited Great and Little Miami River Basins to remove parts not in Great/Little Miami river basins. Based mostly on 1:2,000,000 HUC boundaries. Added area containing Cincinnati (from north bank of Ohio river and beyond), using the 1:2,000,000 streams. Changes approved by Rod Sheets.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Replaced Kentucky River Basin with 1:24,000 coverage from Robert Forbes.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Expanded Yellowstone River Basin to include Bighorn River.
Version 4.0 - Changes arose during the effort to prioritize the FY 1997 Study Units. Removed Central Oklahoma and Central High Plains. Replaced them with two new areas: Middle Arkansas River Basin and Canadian-Cimarron River Basins. The new coverages were extracted mostly from the 1:250,000 HUC coverage. Part of the boundary came from an 11-digit HUC coverage. HUC 11060006050 was added to Canadian-Cimarron area and removed from Middle Arkansas so that all of the Keystone Reservoir was included in the Canadian-Cimarron. Original coverages were supplied by Jamie Schlottmann Norvell. The new boundaries replaced those of Rio Grande, Southern High Plains, Upper Arkansas, and Kansas where they were adjacent to the existing boundaries.
Version 4.1 - Northwestern portion of Mississippi Embayment boundary was expanded by adding HUC 7140107 and the western portion of HUC 11010014; Northern New England Basins and Southeastern New England Basins merged into one Study Unit - New England Coastal Basins (NECB), scheduled to begin in fiscal year 1997.
Version 4.2 - Northern Rockies Intermontane Basins, Great Salt Lake, Southern High Plains - all of which were originally '94 Study Units - have become '97 Study Units. Kentucky, Canadian-Cimarron, Upper Arkansas, Kansas, North Platte, and Cheyenne - all formerly '97 Study Units - no longer have a scheduled date. The latter set of Study Units are identified as GROUP 4 Study Units.
Version 4.3 - Item NAWQA was renumbered to reflect the merging of Northern New England Basins and Southeast New England Basins.
Version 4.4 - Minor revision to Upper Tennessee. The Study-Unit boundary was replaced with the basin boundary for station 03568000, which is the integrator site for the entire Upper Tennessee. Removed Lake Okeechobee from Southern Florida Study Unit, since no other lakes are delineated separately.
Version 4.5 - Replaced South Central Texas with enhanced boundary coverage from Lu Tan; replaced Connecticut with enhanced boundary coverage from Pete Steeves.
Version 4.6 - Expanded item NAME in .PAT from 40 characters to 50 characters so full Study-Unit names (with no abbreviations) could fit into this field.
Version 4.7 - Changed Delmarva and Yakima from group 3 to group 4 in accordance with email from Bill Wilber.
Version 5 - Incorporated new boundaries for UIRB and LIRB using coverages supplied by the Study Units. The LIRB boundary was higher resolution than the UIRB boundary, so the LIRB boundary had priority where the two shared a boundary. The WMIC boundary was replaced where it was coincident with UIRB. Changed Study-Unit starting dates to match recent programmatic changes within NAWQA. Group 4 = Planned to begin in FY 99 (DLMV, YAKI) Group 5 = Unscheduled (CHEY, KNTY, UARK) Group 6 = Unscheduled, overlap the High Plains study (CACI, KANS, MARK, NPLT, SHPL) Group 7 = CNBR (overlaps the High Plains study; now in a separate group to distinguish it from other FY 91 studies) Changed item CANADA to INTL. Changed item ABBV to SUID to be consistent with NAWQA data base network tables.
Version 5.1 - Replaced DELR boundary with one supplied by Paul Dunne. The boundary was extended to include the entire Christina River Basin. This change also affects the DLMV.
Version 5.2 - Replaced ALMN boundary with higher resolution boundary provided by James Sams III; also replaced MIAM boundary with enhanced boundary provided by Lori Mattern.
Version 5.3 - Small change to UMIS boundary provided by Paul Hanson.
Version 5.4 - Changes to boundaries of YELL (Ron Zelt), NROK (Deann Dutton), UIRB (Terri Arnold), DELR (Paul Dunne),
Version 5.5 - Changes to boundaries of SANA (Katherine Paybins).
Version 6.0 - CHANGED HORIZONTAL DATUM FROM NAD27 TO NAD83.
Version 6.1 - Changed back to 4 main NAWQA groups: group 1 (studied 1991-95), group 2 (studied 1994-98), group 3 (studied 1997-2001), and group 4 (not scheduled for study during cycle 1 of NAWQA). We no longer need to distinguish which Study Units overlap the High Plains. Removed items G5BND, G6BND, G7BND from arc attribute table. Added item ACTUALLY_STUDIED to polygon attribute table. Coded annotation $level to match Study Unit group.
Changed name of coverage from NAWQA to NAWQACYC1 to distinguish it from the coverage containing the NAWQA cycle 2 boundaries (NAWQACYC2).
Revised names to match those in USGS Fact Sheet 071-01.
Calculated cover-id equal to cover# - 1. Changed name of ACTUALLY_STUDIED to STUDIED.
Data set converted to geodatabase feature class format.
Data set projected to NAD 83 Albers Equal Area
Dataset copied.
Feature geometry.
ESRI
Flag for group 2 boundaries
NAWQA
1=group 2 boundary; 0=not group 2 boundary
User assigned
Internal feature number.
ESRI
Length of feature in internal units.
ESRI
Area of feature in internal units squared.
ESRI
Internal feature number.
ESRI
Feature geometry.
ESRI
Area of feature in internal units squared.
ESRI
Perimeter of feature in internal units.
ESRI
n/a
GIS software
Internal feature number.
ESRI
Loosely based on WRD region. Values 1-57 are NAWQA Study Units. 0 is not a NAWQA Study Unit.
User assigned
User-defined feature number.
ESRI
See table 1.
User assigned
Code for starting date of Study Unit
NAWQA program
1= studied 1991-95; 2= studied 1994-98; 3= studied 1997-2001; 4= Not scheduled; 0= Not a NAWQA Study Unit.
User assigned
Flag for Pilot study
NAWQA program
1=pilot study; 0=not pilot study
User assigned
4-letter abbreviation for Study Unit
NAWQA program
See Entity_and_Attribute_Overview
User assigned
Flags polygons in Canada (REDN,PUGT,CONN) or Mexico (CAZB)
NAWQA
1=in Canada or Mexico; 0=not in Canada or Mexico
User assigned
Area of polygon in square miles
NAWQA
AREA * .0000003861
User assigned
USGS water-resources administrative region
USGS
USGS Water Resources Division administrative region: N=northeastern; S=southeastern; C=central; W=western
User assigned
Flag for whether NAWQA Study Unit was actually studied during Cycle 1 of NAWQA (1991-2001).
USGS
Flag for whether the Study Unit was actually studied or not during Cycle 1 of NAWQA. Y = was studied during Cycle 1 (that is, group = 1,2,3). N = was not studied during Cycle 1 (group = 4). Blank = was not a designated Study Unit (group = 0).
User assigned
There are two attribute files associated with this coverage. An arc attribute table (.AAT): >DATAFILE NAME: NAWQACYC1.AAT > 9 ITEMS: STARTING IN POSITION 1 > COL ITEM NAME WDTH OPUT TYP N.DEC > 01 FNODE# 4 5 B - > 05 TNODE# 4 5 B - > 09 LPOLY# 4 5 B - > 13 RPOLY# 4 5 B - > 17 LENGTH 4 12 F 3 > 21 NAWQACYC1# 4 5 B - > 25 NAWQACYC1-ID 4 5 B - > 29 USBND 1 1 I - > 30 INTL 1 1 I - > 31 SUBND 1 1 I - > 32 G1BND 1 1 I - > 33 G2BND 1 1 I - > 34 G3BND 1 1 I - > 35 G4BND 1 1 I - where: >arcs representing the boundary of the United States are flagged USBND = 1 >arcs representing Study-Unit boundaries in Canada or Mexico > are flagged INTL = 1 >arcs representing Study-Unit boundaries are flagged SUBND = 1 >arcs representing group 1 Study-Unit boundaries are flagged G1BND = 1 >arcs representing group 2 Study-Unit boundaries are flagged G2BND = 1 >arcs representing group 3 Study-Unit boundaries are flagged G3BND = 1 >arcs representing group 4 Study-Unit boundaries are flagged G4BND = 1 AND a polygon attribute table (.PAT): >DATAFILE NAME: NAWQACYC1.PAT >11 ITEMS: STARTING IN POSITION 1 >COL ITEM NAME WDTH OPUT TYP N.DEC ALTERNATE NAME > 01 AREA 4 12 F 3 > 05 PERIMETER 4 12 F 3 > 09 NAWQACYC1# 4 5 B - > 13 NAWQACYC1-ID 4 5 B - > 17 NAWQA 4 4 I - > 21 NAME 50 50 C - > 71 GROUP 2 2 I - > 73 PILOT 1 1 I - > 74 SUID 4 4 C - ABBV > 78 INTL 1 1 I - CANADA > 79 MI2 4 10 F 0 > 83 REGION 1 1 C - > 84 STUDIED 1 1 C - NAWQA is the Study-Unit number, which is a sequential number from 1-57. The numbers originally were based on administrative regions, but are not anymore. See table 1. NAME contains the full name of the Study Unit. See table 1. GROUP represents the assessment schedule of Study-Unit investigations: >Group 1 = Assessed during 1991-1995 >Group 2 = Assessed during 1994-1998. >Group 3 = Assessed during 1997-2001. (Includes DLMV and YAKI, > which started in 1999.) >Group 4 = Not scheduled for study during cycle 1. (KNTY, UARK, CHEY, CACI, NPLT, MARK, SHPL, KANS). PILOT flags those polygons that were pilot projects, although the boundaries of the pilot projects were not maintained in this coverage. (For example, COKL boundaries were replaced when CACI was delineated.) SUID contains the 4-letter abbreviation for the Study Unit. The alternate name is ABBV. See table 1. INTL flags those polygons located in Canada or Mexico. Usually polygons outside of the United States are NOT plotted on national displays of the boundaries. INTL is in both the .AAT and the .PAT and is used primarily for plotting purposes. (USBND, SUBND, G1BND, G2BND, G3BND, and G4BND are in the .AAT and are also used for plotting.) MI2 is the area of an individual polygon in square miles, calculated as MI2 = AREA * .0000003861. To find the area of an entire Study Unit, sum the areas of the individual polygons comprising the Study Unit. REGION is the USGS water resources administrative region: >N = Northeast >S = Southeast >C = Central >W = Western STUDIED is a flag for whether the Study Unit was actually studied during cycle 1 of NAWQA (1991-2001). >Y = actually studied during cycle 1 >N = not studied during cycle 1 >Blank = was not designated as a Study Unit during cycle 1 Table 1.--NAWQA 4-letter abbreviations (SUID), names (NAME), and numbers (NAWQA). > SUID NAME NAWQA NUMBER > ACAD ACADIAN-PONTCHARTRAIN DRAINAGES 28 > ACFB APALACHICOLA-CHATTAHOOCHEE-FLINT RIVER BASINS 22 > ALBE ALBEMARLE-PAMLICO DRAINAGES 19 > ALMN ALLEGHENY-MONONGAHELA RIVER BASINS 9 > CACI CANADIAN-CIMARRON RIVER BASINS 32 > CAZB CENTRAL ARIZONA BASINS 49 > CCPT CENTRAL COLUMBIA PLATEAU 50 > CHEY CHEYENNE-BELLE FOURCHE RIVER BASINS 42 > CNBR CENTRAL NEBRASKA BASINS 35 > CONN CONNECTICUT, HOUSATONIC, AND THAMES RIVER BASINS 2 > DELR DELAWARE RIVER BASIN 5 > DLMV DELMARVA PENINSULA 7 > EIWA EASTERN IOWA BASINS 30 > GAFL GEORGIA-FLORIDA COASTAL PLAIN DRAINAGES 23 > GRSL GREAT SALT LAKE BASINS 47 > HDSN HUDSON RIVER BASIN 3 > KANA KANAWHA-NEW RIVER BASIN 10 > KANS KANSAS RIVER BASIN 36 > KNTY KENTUCKY RIVER BASIN 25 > LERI LAKE ERIE-LAKE ST. CLAIR DRAINAGES 11 > LINJ LONG ISLAND-NEW JERSEY COASTAL DRAINAGES 4 > LIRB LOWER ILLINOIS RIVER BASIN 15 > LSUS LOWER SUSQUEHANNA RIVER BASIN 6 > LTEN LOWER TENNESSEE RIVER BASIN 29 > MARK MIDDLE ARKANSAS RIVER BASIN 38 > MIAM GREAT AND LITTLE MIAMI RIVER BASINS 12 > MISE MISSISSIPPI EMBAYMENT 27 > MOBL MOBILE RIVER BASIN 26 > NECB NEW ENGLAND COASTAL BASINS 1 > NPLT NORTH PLATTE RIVER BASIN 41 > NROK NORTHERN ROCKIES INTERMONTANE BASINS 46 > NVBR NEVADA BASIN AND RANGE 55 > OZRK OZARK PLATEAUS 31 > POTO POTOMAC RIVER BASIN 8 > PUGT PUGET SOUND DRAINAGES 52 > REDN RED RIVER OF THE NORTH BASIN 18 > RIOG RIO GRANDE VALLEY 45 > SACR SACRAMENTO RIVER BASIN 54 > SANA SANTA ANA RIVER BASIN 57 > SANJ SAN JOAQUIN-TULARE RIVER BASINS 56 > SANT SANTEE RIVER BASIN AND COASTAL DRAINAGES 21 > SCTX SOUTH-CENTRAL TEXAS 34 > SHPL SOUTHERN HIGH PLAINS 39 > SOFL SOUTHERN FLORIDA DRAINAGES 24 > SPLT SOUTH PLATTE RIVER BASIN 40 > TRIN TRINITY RIVER BASIN 33 > UARK UPPER ARKANSAS RIVER BASIN 37 > UCOL UPPER COLORADO RIVER BASIN 44 > UIRB UPPER ILLINOIS RIVER BASIN 14 > UMIS UPPER MISSISSIPPI RIVER BASIN 17 > USNK UPPER SNAKE RIVER BASIN 48 > UTEN UPPER TENNESSEE RIVER BASIN 20 > WHIT WHITE RIVER BASIN 13 > WILL WILLAMETTE BASIN 53 > WMIC WESTERN LAKE MICHIGAN DRAINAGES 16 > YAKI YAKIMA RIVER BASIN 51 > YELL YELLOWSTONE RIVER BASIN 43 >--------------------------------------------------------------------- > Hawaii and Alaska (not included in this data set) >--------------------------------------------------------------------- > OAHU OAHU 58 > COOK COOK INLET BASIN 59 >--------------------------------------------------------------------- > High Plains (not included in this data set) >--------------------------------------------------------------------- > HPGW HIGH PLAINS REGIONAL GROUND WATER STUDY -- The coverage also contains annotation showing the 4-letter Study-Unit abbreviations. Annotation codes: >$level = 1 (group 1 abbreviations) >$level = 2 (group 2 abbreviations) >$level = 3 (group 3 abbreviations) >$level = 4 (group 4 abbreviations)
Not Available
1500 Research Parkway, Suite B223
None
Data can be downloaded from www.geostac.org with a registered user ID and password provided by the Spatial Sciences Laboratory.
Not Applicable
897-B Harrison Street, S.E.