1. Moving from 1:100K NHD to 1:24K Resolution: Case Studies Paul Andrews (presenter), Peter Ilieve, Ken Gilland, Bill Cooter (RTI International) Bill Kramer, and Thomas Dewald (U.S. EPA)

2. Acknowledgements Thomas Dewald (U.S. EPA/AWPD) Bill Kramer (U.S EPA/OST) Thomas Dabolt (U.S. EPA/AWPD) Michael Plastino (U.S. EPA/IO) Prepared by RTI International under contract with EPA Office of Water

3. Introduction Background Information Comparison of 1:100K NHD to 1:24K NHD Case Studies of 303(d), 305(b), and WQS Reach Indexing to 1:24K NHD

4. Overview 4

5. http://www.epa.gov/waters/enviromapper

6. Indexing Tools and Resources National Hydrography Dataset (NHD) NHD Reach Indexing Tool (NHD-RIT) Automated Georeferencing Processes (e.g., for Adding General Use Waters)

7. National Hydrography Dataset (NHD)  Set of spatial data that contains information about surface water features.  Surface water features are represented by "reaches," which are assigned unique identifiers  Contains 52 feature types including: streams, lakes, reservoirs, canals and dams.  Based upon the USGS Digital Line Graph (DLG) hydrography and the EPA Reach File Version 3 (RF3).  1:100,000-scale NHD (hi res IP)  NHD is available online at http://nhd.usgs.gov/

8.  Georeferencing (reach indexing): The process of describing (or locating) entities in a GIS coverage; assigning an NHD reach code to the waterbody feature.  Reach Indexing Tool (RIT): ArcView 3.x extension; Tool for georeferencing surface water features to reaches in NHD.  Georeferencing and RIT are available online at: www.epa.gov/owow/monitoring/georef/ www.epa.gov/owow/monitoring/georef/  RIT was 1 st and 2 nd prize winner at the ESRI International User Conferences in San Diego, CA

9. EPA Program Database Link to GIS Database Event Table Indexed to NHD NHD Coverage GIS Map MO1009 MO1008 MO1010 10300102003685

11. 20 Subbasins Analyzed from 18 States

12. KY Subbasin 05130102

13. 1:100K NHD/1:24K NHD Comparison KY Subbasin 05130102

14. 1:100K NHD Reach KY Subbasin 05130102 0 100

15. 1:24K NHD Reach KY Subbasin 05130102 0 100

16. 1:100K 1,129 2,342 37.43 1:24K 3,482 1,279 16.92 Comparison of 1:100K and 1:24K NHD Subbasins: Linear Reaches Average Number Average Length (m) Percent Named

17. 1:100K 100 0.222 23.45 1:24K 1,291 0.026 2.54 Comparison of 1:100K and 1:24K NHD Subbasins: Waterbody Reaches Average Number Average Area (km 2 ) Percent Named

18. Name Chattahoochee River, GA White River, VT Green River, WY Teagle Wash, CA Mississippi River, MN Change 19% 2% <1% -9% -14% Change in Reach Length for Specific Rivers

19. 303(d) Georeferencing

20. Name Crooked Creek Brush Creek Wood Creek Increase 1% 2% 27% Increase in 303(d) Reach Length for Kentucky Rivers: Subbasin 05130102

21. Name Monongahela River Owl Creek Laurel Run Increase 1% 3% 4% Increase in 303(d) Reach Length for West Virginia Rivers: Subbasin 05020003

22. KY Subbasin 05130102

23. 1:100K to 1:24K Shape Comparison KY Subbasin 05130102

24. Name Wood Creek Lake, KY Deckers Creek Reservoirs, WV Laurel Run Reservoirs, WV Los Gatos Creek Reservoirs, CA Coyote Creek Reservoirs, CA Change -15% -2% -25% 5% 12% Change in 303(d) Reach Areas for Lakes

25. 305(b) Georeferencing

26. WV Subbasin 05020003

27. Added 1:24K Lakes WV Subbasin 05020003

28. Water Quality Standards Georeferencing

29. NE Subbasin 10220004

30. 1:100K Indexing with Point Event NE Subbasin 10220004

31. 1:24K Indexing with Reach Located NE Subbasin 10220004

32. WV Subbasin 05020003

33. 1:24K General Use Waters WV Subbasin 05020003

34. Attribute Total Reach Length Total Waterbody Area Increase 39% 53% Increase in Total Reach Length and Area for KY Subbasin 05130102

35. Conclusions 1:24K NHD significantly increases the number of waterbodies that can be mapped Greater detail changes the shapes and lengths of NHD features Changes will impact mapping activities for all programs – tools will minimize impact

36. More Information & Training NHD web site: http://nhd.usgs.gov/ NHD-RIT and Reach Indexing Web Site: www.epa.gov/owow/monitoring/georef/ EPA Watershed Assessment, Tracking & Environmental Results (WATERS) http://www.epa.gov/waters/ EPA Office of Water EnviroMapper http://www.epa.gov/waters/enviromapper