Application of SPARROW Results for Nutrient Criteria Development in New England

1. Application of SPARROW Results for Nutrient Criteria Development in New England New England Association of Environmental Biologists Annual Conference March 17, 2004 Matthew Liebman, U.S. EPA, New England

2. Overview of Presentation • Nutrient Criteria Development for rivers • Principles and assumptions of nutrient criteria • Development of New England rivers and streams (R/S) nutrient database to determine reference condition • Applications of the SPARROW model • Determining population of reference rivers and streams • Determining statistical reference condition; a comparison of nutrient database and SPARROW estimates • Testing assumptions of ecoregional nutrient criteria • Linking SPARROW estimates to use impairments • Use of SPARROW results in a consensus weight of evidence approach • Summary

3. Why do we need numeric nutrient criteria? • Lakes, rivers and estuaries are enriched with nutrients from sewage treatment plants, agricultural and urban runoff and atmospheric deposition • Clean Water Act says EPA sets criteria to protect designated uses, such as swimming and aquatic life • States typically have narrative standards, such as: “sources should be controlled to prevent eutrophication.” Numeric criteria supplements existing narrative WQ standards • Narrative standards are ambiguous, and waterbodies are still impaired • Percent of lakes impaired in New England: > 20 • Percent of rivers impaired in New England: > 5

4. Unimpaired stream reaches(credits: USGS, ENSR)

5. Impaired stream reaches(credits: Organization for the Assabet River)

6. How will nutrient criteria for rivers and coastal waters be applied? • WWTP Permit limits for phosphorus and nitrogen -- in some streams, WWTP effluent is greater than 80% of total summertime flow! • Target levels for Total Maximum Daily Loads (TMDLs), especially in downstream nutrient sensitive reaches • States assess waterbodies to determine whether designated uses are protected. If uses are not protected, states must enforce conditions to ensure uses are protected

7. WWTPs in Sudbury, Assabet and Concordriver watershed(source: EPA)

8. EPA’s National Nutrient criteria strategy • EPA publishes technical guidance manuals • EPA publishes water quality recommendations, or ecoregional nutrient criteria, or reference conditions • States to refine the reference conditions with additional information • historical information • model results (e.g. SPARROW) • effects of nutrients on response variables – use impairment approach • importantly, consider downstream reaches, e.g. impoundments and estuaries • States to submit nutrient criteria implementation plan to adopt criteria into standards by 2004

9. Timeline of Nutrient Criteria Development/Adoption

10. Principles of ecoregional nutrient criteria • Nutrient enrichment usually manifested as an undesirable biological response ( e.g. increased frequency of algal blooms, that impairs recreational, aesthetic or aquatic life uses • Identify nutrient and biological levels below which nuisance or impaired conditions are unlikely to occur; thus designated uses are protected • Causal (phosphorus and nitrogen) and Response (chlorophyll a, secchi disk transparency or turbidity) variables • Reference condition is presumed to vary by ecoregion, or by class of lake or river

11. Classification of rivers by size - differential nutrient sensitivity and response(credits: ENSR, NEIWPCC) • Wadeable streams exhibit potential for excessive periphyton growth • Impoundments exhibit phytoplankton or macrophyte (duckweed) blooms in summer

12. Assumptions of the ecoregional nutrient criteria reference condition approach • Reference conditions are statistically derived based on representative population of rivers, including known reference rivers • Reference conditions are attainable • Reference conditions are protective of designated uses • Reference conditions differ among ecoregions, due to geology, landscape factors • Waterbodies can be classified based on ecoregional or other, e.g. physical, factors, e.g. size, depth

13. 10 15 20 25 Reference condition (Statistical) approach for developing nutrient criteria: Good Water Quality Poor Water Quality

14. EcoRegion TP (ug/L) TN (mg/L) Chl a (ug/L) Secchi (m) I 47.0 0.31 1.80 4.25 II 10.00 0.12 1.08 1.30 III 21.88 0.38 1.78 2.34 IV 23.00 0.56 2.40 4.21 V 67.00 0.88 3.00 7.83 VI 76.25 2.18 2.70 6.36 VII 33.00 0.54 1.50 1.70 VIII 10.00 0.38 0.63 1.30 IX 36.56 0.69 0.93 5.70 X 128 0.76 2.10 17.50 XI 10.00 0.31 1.61 2.30 XII 40.00 0.90 0.40 1.90 XIV 31.25 0.71 3.75 3.04 Range of EPA WQ Recommendations for rivers

15. Development of New England region specific rivers and streams nutrient database • With RTAG guidance and assistance from states, we developed a region-specific database of measurements of nutrients (and biological parameters where available) in rivers and streams • Enhancements over national database • More recent data • Not just from national databases • Supplemented with information on biological response variables, reference/impaired condition, or an impoundment • Determined reference waterbodies

16. Major sources of river and stream nutrient and watershed data in New England • Federal Agencies • STORET (CT, MA, ME, NH, RI, VT) • EMAP (CT, MA, NH) • NAWQA • USGS • State Water Quality Agencies & RTAG • CT DEP, MA DEP, ME DEP, NH DES, RI DEM, VT DEC

17. NE R/S Nutrients Database Structure SYSTEM Watershed, Ecoregion System ID “Ecoregions” Parameters WATERBODY River, Stream, Creek Waterbody ID STATION Measurement station at given location on water body Station ID SAMPLE Sample taken at given date/time and water depth Lookup Table Sample ID Data Table WATER QUALITY MEASUREMENT value measured for a specific parameter One-to-Many Relationship

18. Number of rivers and streams in New England nutrient database

19. Rivers and streams nutrient databaseby ecoregions (source, ENSR) • Eastern Great Lakes & Hudson Lowlands (EGLHL) - 14 • Laurentian Plains and Hills (LPH) - 21 • Northeastern Highlands (NEH) - 316 • Northeastern Coastal Zone (NECZ) - 206

20. Calculation of four season median value

21. USGS SPARROW - • New England model • network of river • reaches and watersheds • Based on the 1:100,000 scale National Hydrography • Data Set (NHD) • 42,000 reaches in model • Average size is 1.7 mi2 • Corrected to NRCS 12-digit watersheds • Hydrologically connected

22. Application of the SPARROW model • Determining reference reaches • Estimated mean annual flow weighted concentration predictions for phosphorus and nitrogen for each small watershed reach (42,000 in New England) • Compare nutrient concentrations among ecoregions • Link estimates of watershed nutrient concentrations to independently collected biological response data (e.g. periphyton growth or macro invertebrate assessments) • Use predicted concentrations as target levels for a particular grouping of watersheds for TMDL or nutrient criteria development purposes • Estimate nutrient loads to downstream waterbodies, e.g. estuaries, or impoundments

23. Determining population of reference rivers and streams • Used SPARROW model to defined watershed reference conditions (similar to protocol of Rohm et al., 2002) based on land use: • Watershed has < 1% of urban land use • Watershed has < 5% agricultural land use • Watershed population density < 20 people/sq. mi. (equivalent to the 10th percentile of population) • Compared reference conditions from all rivers among four ecoregions

25. Estimated mean annual flow weighted concentration predictions for phosphorus and nitrogen for each small watershed reach (42,000 in New England)

26. Estimated Mean Annual concentration of (A) Nitrogen and (B) phosphorus.

27. The Results! A comparison of NE nutrient database percentiles vs. US EPA AWQC Recommendations by ecoregion

28. The Results! A comparison of NE nutrient database percentiles vs. SPARROW results by ecoregion

29. Compare nutrient concentrations among ecoregions

31. Summary of SPARROW results for nutrient criteria development • SPARROW useful in determing reference reaches • Reference condition estimates are similar, but usually higher than, results from database • Ecoregions clearly are different

32. Additional uses of SPARROW Model – Link estimates of watershed nutrient concentrations to independently collected biological response data (e.g. periphyton growth or macro invertebrate assessments)

33. Nutrients and periphyton biomassregression equations (source, ENSR) • General nutrient-periphyton regression equations were backcalculated to provide TP and TN levels resulting in <100 mg/m2 chl a biomass: TP = 47 ug/L TN < 0.97 mg/L

34. Total Phosphorus Impaired Sites Total Nitrogen Impaired Sites .6 8 Subecoregion 59 .024 mg/L Subecoregion 59 0.57 mg/L 7 .5 6 .4 5 4 Milligrams per liter .3 Milligrams per liter 3 .2 2 0.75 mg/L .1 0.037 mg/L 1 0 0 90th 50th 75th 10th 25th 90th 50th 75th 10th 25th Percentile Percentile (source, USGS)

35. Reference condition (Statistical) approaches Nutrient-periphyton relationships Upper bound criteria to avoid use impairment in NECZ TP = 10 to 44 ug/L TN = 121 to 568 ug/L TP = 40-47 ug/L TN = 800 to 1000 ug/L TP < 40 ug/L TN < 800 ug/L Establishing consensus nutrient criteria through weight-of-evidence approach

36. Considering downstream effects • Selecting a concentration to protect uses in stream may not protect uses downstream • EPA’s regulations at CFR Part 131.10(b) require that in “designating uses of a waterbody and the appropriate criteria for those uses, the State shall take into consideration the water quality standards of downstream waters and shall ensure that its water quality standards provide for the attainment and maintenance of the water quality standards of downstream waters.” • SPARROW may help by estimating loads to downstream impoundments and estuaries

37. Summary • States need to develop nutrient criteria refining the reference condition approach • Nutrient criteria will affect NPDES, TMDL and water quality assessment programs • SPARROW results tested assumptions of the ecoregional nutrient criteria reference conditions approach, that ecoregions matter • SPARROW and other results yield a relatively “narrow” range of criteria • SPARROW may also be useful for developing nutrient criteria, e.g. linking nutrient concentrations to biological effects, and considering downstream effects

38. EPA Technical Guidance Manuals and web site for ecoregional nutrient criteria, andnational nutrient database • U.S. EPA 2000, Nutrient Criteria Technical Guidance Manual, Rivers and Streams, Technical Guidance Manual, Interim Final • U.S. EPA. 2000, Nutrient Criteria Technical Guidance Manual, Lake and Reservoirs, Technical Guidance Manual, Interim Final Draft • U.S. EPA. 2001, Nutrient Criteria Technical Guidance Manual, Estuaries and Coastal Marine Waters , Technical Guidance Manual, Interim Final Draft • www.epa.gov/waterscience/standards/nutrient.html

39. Rivers and streams documents • NEIWPCC and ENSR Corporation. 2001. The Relationship Between Nutrient Concentrations and Periphyton Levels in Rivers and Streams – A Review of the Scientific Literature. Final Report. August, 2001 • NEIWPCC and ENSR Corporation. 2003. Collection and Evaluation of Ambient Nutrient Data for Rivers and Streams in New England – Data Synthesis Report. September 2003 • www.neiwpcc.org