Addressing Maryland’s Sediment Impairments

1. Addressing Maryland’s Sediment Impairments Lee Currey TMDL Program Non-tidal and Watershed Modeling Division September 11, 2014

2. Acknowledgments • EPA Chesapeake Bay Program • EPA Region III • ICPRB • MD Department of Natural Resources • University of Maryland • USGS • Versar, Inc • Virginia Institute of Marine Sciences

3. Outline • Listing Methodologies • 303(d) Sediment Listings • Identifying a Sediment Stressor • Sediment TMDL Approach • Current Project Status • Outstanding Issues

4. Listing Methodologies for Solids • Water Clarity • Turbidity [COMAR 26.08.02.03-3(A)(5)] • May not exceed levels detrimental to aquatic life • May not exceed 150 units at any time or 50 units as a monthly average • Narrative Water Quality Criteria • “…State’s waters must be sufficient quality to provide for the protection of and propagation of a balanced population of shellfish, fish and wildlife and allow for recreational activities…” [COMAR 26.08.02.01-B(2)] (i.e. fishable/swimmable)

5. History of Maryland Sediment Impairments • Existing water quality inventory [303(d) list] identified 97 listings for sediment • Many watersheds assessed based on land use and likelihood of sediment impairment • Currently no distinction between “suspended sediment” and “sedimentation”

6. Sediment Impairments

7. What is a “Clean” Sediment Impairment? Basin erosion Channel/Bank erosion Source Increased suspended sediments Substrate homogeneity Current homogeneity Stressor Interruption in feeding mechanisms Decreased habitat Process Response Shift in biological community (biocriteria)

8. Identifying a Sediment Stressor • Endpoint – Maryland Biocriteria • Stressor – Sediment Related Physical Habitat Parameters • Linkage – Statistical Model

9. MBSS and Biocriteria • Stratified random sampling of first to fourth order stream (fourth in round 2) • Index of biotic integrity • Biological condition indicator developed for the fish and benthic communities • Multi-metric - aggregates multiple characteristics of biological assemblage • Established from regional reference conditions • Biocriteria is EPA approved • For evaluating biological data for CWA requirements

10. MBSS Monitoring Round 2: Approx 10 stations per 8-digit basin

11. Identifying Surrogate Sediment Parameters • Variables that best represent the presence or effects of sediment • Combined physical habitat • Riparian and upland zone • Streambed • Channel features • Water column • 27 variables identified from total MBSS set • Reviewed by advisory committee

12. Identifying Surrogate Sediment Parameters • Further refinement of surrogate parameters: • Available for both rounds of MBSS sampling • Expected to have discriminatory power and thus not be limited in range of recorded values • Not confounded by stream size or other critical natural variables • Not completely redundant

13. Surrogate Variables Definition Scoring Relationship to Sediment Riffle/Run Quality Depth, complexity, and functional importance of riffle/run habitat 0 to 20 High scors indicate lack of sediment deposition. Bank stability Composite score. Presence or absence of riparian vegetation quantitative measures of erosion extent and erosion severity. 0 to 100 High scores indicate lack of channel erosion Riparian buffer width Width of vegetated (i.e., grass, shrubs, or trees) riparian buffer 0 to 50 Indirectly related to sedimentation as buffers remove sediment in runoff and protect banks from erosion. Instream habitat Perceived value of instream habitat to the fish community, including multiple habitat types, varied particle sizes, and uneven stream bottom. 0 to 20 High socres indicate lack of sediment deposition. Epifaunal Substrate Visual rating based on the amount and variety of hard, stable substrates usable by benthic macroinvertebrates. 0 to 20 High scores indicate lack of sediment deposition. Embeddedness Percentage of gravel, cobble, and boulder particles in the streambed that are surrounded by fine sediment. 0 to 100 Direct evidence of sediment deposition. Parameters Used in Analysis

14. Non-Sediment Stressors • MBSS sites with stressors not related to sediment • Acidification • ANC < 200 μeq/l and DOC < 8 mg/l (excluding natural blackwater) • Urbanization • Urban land use > 10% • Cl > 50 mg/l • Low dissolved oxygen • Not removed due to instantaneous sampling methodology

15. Methodology

16. Region Parameter 1 Parameter 2 Parameter 3 Parameter 4 Highland Riffle run Riparian width Embeddedness ----------------- Piedmont Riparian width Instream habitat Embeddedness Epifaunal substrate Coastal Riffle run Riparian width Instream habitat ----------------- Statewide Riffle run Riparian width Instream habitat Embeddedness Parameter Selection • Select most parsimonious model • Objective is change in Chi square value

17. Model Summary Statistics

18. Model Validation Model Validation * Inconclusive based on 90% confidence interval

19. Watershed Evaluation for Sediment Impairment • Estimate likelihood of sediment impairment at appropriate management scale • MDE currently lists sediment impairment at the MD 8-digit scale • Average likelihood of sediment impairment per watershed

20. Evaluation of Model at Watershed Scale Surrogate Sediment Parameters IBI Note: 1. Min sample>=5

21. TMDL Approach – Reference Watershed Statewide Analysis MD 8-digit management scale Watershed clustering (similar to Preston, 2002) Sediment loads Likelihood of Sediment Impairment Target Load

22. Watershed Clustering • Reviewed previous results from USGS (Preston, 2000) • Updated cluster analysis based on new data and focused on sediment • Two stage clustering • hydrological and geological information • Rainfall erosivity (R) • soil erodibility (K) • watershed slope • Land use

23. Watershed Clustering Example

24. Watershed Clustering Example

25. CBP Phase V • Interstate coordination • MD 8-digit watershed scale

26. Sediment Loads DRAFT *Preliminary CBP Phase V Loads

27. Addressing 303(d) Listings • WQA • Determined from likelihood of sediment impairment • Inferential statistics used to address borderline cases • TMDL • Reference watersheds • Watershed model scenarios • Limits of implementation • Maximum practical reductions

28. Where are we now? • Independent review of logistic regression model • Working on two stage clusters • talking with USGS about best cluster methods for reference watersheds • Coordinating with CBP (USGS and ICPRB) on Phase V sediment calibration

29. Outstanding Issues • Normalizing loads • Scale of impairment • Sediment loads for reference conditions • Point sources • MS4 permits

30. Thanks !Questions and Comments