The concept of a Master Sample: An Oregon Case Study

1. The concept of a Master Sample:An Oregon Case Study Phil Larsen Tony Olsen USEPA, Corvallis, OR Larsen.phil@epa.gov Olsen.tony@epa.gov Don Stevens Oregon State University Stevens@stat.orst.edu www.epa.gov/nheerl/arm

2. Background • Many agencies interested in regional scale monitoring of stream networks and watersheds, using similar attributes and similar/same protocols • Can’t afford to monitor everywhere (i.e., can’t census) • Conducting a sample survey a sound way to characterize a region by monitoring a representative set of sites

3. From Stevens and Olsen, 2004Spatially balanced sampling of natural resources. JASA 99:262-278 • “Sampling the gamut of natural resources requires a technique that can select a spatially balanced sample of finite, linear, and areal resources with patterned and possibly periodic responses, using arbitrarily variable inclusion probability with imperfect frame information, in the presence of substantial nonresponse”

4. EMAP’s Design Approach • GRTS: Generalized Random Tessellation Stratified design • Incorporates randomization • Is spatially balanced • Creates an ordered list of sites • See: www.epa.gov/nheerl/arm for details

6. Combining Data • Data from different sample surveys can be combined if certain design principles are followed • Similar target populations are well defined • The same frame represents the target populations (i.e., use the same digital stream trace coverage) • Randomization in site selection • Common protocols are used to measure stream attributes

7. A Desirable Goal • Create a design that allows and facilitates integration up front rather than after the fact. • Current GRTS design allows selection of a “master” sample that can be subset to meet specific needs at a variety of spatial scales

8. An Oregon Pilot • Frame: USGS 1:100,000 scale digital hydrography (perennial and intermittent) • Selected a statewide sample of about 180,000 points on the network as an ordered list • Any subset drawn in order is a spatially balanced sample • WA: about 125,500 points • Distance between points is approximately 1 km. • Assigned a set of classification variables for sorting the sample

9. Site ID Location (Lat/Long) HUC 4th field code 5th field code 6th field code Strahler order Elevation (e.g., from DEMs) Ecoregion Level 2 Level 3 Level 4 Reporting regions OR DEQ ODFW monitoring areas Ownership Add other geo-referenced variables The Master Sample(An ordered list of sites)

10. WA Master Sample File

12. Oregon Perennial Sites

13. WA Sites by Strahler Order

14. Example • Pick a statewide sample • 50 sites in each of the 5 OR DEQ reporting regions • Equal balance among headwater (1st order), wadeable (2nd, 3rd order) and non-wadeable (4th+ order) streams • About 17 sites per stratum

15. Example • Solution: • Create stream groups: headwater, wadeable, non-wadeable from stream order assignments • Sort the list by DEQ region and stream group within DEQ region, maintaining the original order of sites • Pick the first 17 sites on the list within each DEQ region and stream order group

17. Intensify in three sub-basins

18. Intensify in one National Forest and one BLM District

19. Combine stream network and watershed selection

20. Integrate finer scales

21. Washington Master Sample Example Designs

22. Example Design Characteristics • Equal # of sites by Strahler order categories: 1st, 2nd, 3rd+ • State-Wide design • 1054 unique sites allocated to 6 panels • Panels 1 to 5 visit once every 5 years • Panel 6 visit annually • 1550 site-visits over 5 years • 310 sites per year • WRIA design • 17 sites each WRIA for total 1054 sites • 1054 unique sites allocated to 6 panels • Panels 1 to 5 visit once every 5 years • Panel 6 visit annually • 1550 site-visits over 5 years • 310 sites per year • Intensive design • 50 total sites in 3 WRIAs • 17 sites from WRIA 5 year design and 33 additional sites

23. State-Wide 5 Year: 6 Panel Design

24. State-Wide: Panel 1

25. State-Wide: Panel 2

26. State-Wide: Panel 3

27. State-Wide: Panel 4

28. State-Wide: Panel 5

29. State-Wide: Panel 6

30. WRIA 5 Year Design

31. WRIA Design: Panel 1

32. WRIA Design: Panel 2

33. WRIA Design: Panel 3

34. WRIA Design: Panel 4

35. WRIA Design: Panel 5

36. WRIA Design: Panel 6

37. Intensive Studies + WRIA 5 Year Design

38. Utility of a Master Sample • An exploratory tool to examine different site allocations easily. • A framework for an actual integrated, multi-agency state-wide or regional monitoring program.

39. Flexibility/Potential • Add classification variables by assigning sites to new classes • Requires georeferenced data • Facilitates integration across programs • What sites already being monitored by another agency? • Encourages: • Communication about monitoring designs among agencies • Development of common databases to share data easily • Agreement on common protocols

40. To Make This Work, We Need: • A standard frame that everyone would use, even if imperfect • A process for correcting the frame as errors arise (i.e., frame maintenance) • Institutional Management • Database • Frame and corrections • GIS coverages for classification/stratification • Monitoring programs: who is doing what where? • Monitoring results

41. EndThank You

45. SITE DEQ ODFW AREMP PIBO