Phasing of Nutrient Management Discussions: Biostimulatory Substances and Conditions

1. Phase III Science to Support Nutrient Management Discussions Santa Margarita River Watershed Nutrient Management Initiative Stakeholder Meeting January 23, 2019

2. What Are Biostimulatory Substances and Conditions? Eutrophication = accelerated accumulation of ORGANIC MATTER Organic Matter Dumping Nitrogen and Phosphorus Physical Habitat Alteration Hydromodification Light Temperature We can identify NUTRIENT and organic matternumeric targets (and other factors can be managed at watershed scale) to reduce eutrophication

3. Context for Today’s Meeting Overview of Phasing of Technical Activities • Technical goal of SMR NMI is to pilot alternative approaches to establish “biostimulatory” targets, considering recently available science • Biostimulatory target work has proceeded in three phases: Phase I: Estuary Phase II: Lower Mainstem of SMR - De Luz Confluence to Estuary Phase III: Upper Mainstem of SMR - Top of Gorge to De Luz Confluence

4. Presentation Road Map • Overview of SMR Science Phasing and technical activities • What are we hoping to accomplish in Phase III? • Key findings for Phase II (if needed) • Next steps

5. Tech Team Recommendations for Biostimulatory Indicators Under Consideration for Targets Biostimulatory: • TN and TP Multiple lines of Evidence • Benthic Chl-a and AFDM • Dissolved oxygen, pH range and DO diel variability Bio-confirmation SD Water Board has proposed numeric CSCI targets in support of narrative objective (i.e. Estuary targets uses invertebrates as bioconfirmation) • ASCI and/or CSCI

6. Three Major Options for Establishment of Numeric Targets in Main Stem River Existing RB Basin Plan Biostimulatory Objectives Numeric Translator: TN = 1 mg/L TP = 0.1 mg/L Ranges of biostimulatory conditions linked to DO objectives via mechanistic modeling Recent science supporting new biostimulatory and biointegrity policies for wadeable streams and regional flow ecology • State Water Board • San Diego Board DO objectives Process Model Biostim Targets This science just became available to stakeholders on October 1, 2018

7. Statewide Biointegrity Biostimulatory and Regional Flow Ecology Tools Main Stem

9. Phase II-Status of Technical Activities In May 2018, we completed reports for for three components of Phase II activities; we left these reports in a draft state to continue to Phase III • Findings of upper main stem baseline monitoring (2016-2017), combined with that of the Lower main stem (2015-2016) • Mechanistic modeling system calibration and sensitivity analyses • Refinements to watershed loading model, coupled with CP groundwater model • Lower main stem receiving water models • Synthesis of scientific basis for biostimulatory target and application to mechanistic modeling system and monitoring data in the Lower main stem Reports were be revised and submitted as Phase II grant deliverables, with submission of monitoring data to CEDEN.

10. Proposed Phase III Technical Activities • Workplan describing overview of technical activities (in progress) • Work will proceed pending TAC review • Update of watershed loading model to reflect changes in land use • Development of receiving water quality model in Upper main stem • Already have model for lower Main stem, so connect them end-to-end

11. Boundary Condition (Upper Watershed) Modeling System HSPF model of upper and lower mainstem watersheds Upper River Main Stem CP Diversion MODFLOW Integration Lower River Main Stem • Receiving Water Models of Lower Mainstem • WASP (perennial) • QUAL2Kw (intermittent) CP Diversion Estuary

12. Proposed Phase III Technical Activities • Workplan describing overview of technical activities (in progress) • Update of watershed loading model to reflect changes in land use • Development of receiving water model in Upper main stem • Application of modeling system to facilitate decisions biostimulatory targets, comparing ranges from: • Mechanistic models (extension of WASP models from lower main stem) • Statewide or regional empirical biostimulatory and flow ecology models (leveraged studies) • Considering scenarios that capture potential influence of climate change on flow and temperature

13. Statewide or Regional Biostimulatory and Flow Ecology Empirical Models Flow Metrics We will customize these analyses for Santa Margarita River, using a variety of approaches Biostimulatory Science

14. How Does Climate Change Fit into This Project? Watershed Management Scenarios Altered Land Use Restoration Structural BMPs Altered Water Resource Management Δ Suitable fish habitat DO Water Quality Model (WASP) Biostimulatory Targets Nutrients Flow Restoration Actions Watershed Loading Model (HSPF) Δ flow ΔH20 temp Δ Nutrient Loads ASCI CSCI Climate Predictions Δ precipitation Δ air temp Chl-a Flow Ecology Regional Empirical Modeling Tool ASCI CSCI Δ Aquatic Life

15. Proposed Phase III Technical Activities • Workplan describing overview of technical activities (in progress) • Update of watershed loading model to reflect changes in land use • Development of receiving water model in Upper main stem • Application of modeling system to facilitate decisions on biostimulatory targets, comparing • Mechanistic models (extension of WASP models from lower main stem) • Statewide or regional empirical biostimulatory and regional flow ecology models • Considering scenarios that capture potential influence of climate change on flow and temperature • Analysis of load and waste load allocations 3 year contract; tool development year 1, model application year 2, with time for discussion with Water Board year 3 on proposed actions

16. Phase III Technical Activities: What Will We Accomplish This year? • SMR Nutrient Management Initiative • Workplan (February 2019) • Update calibrated watershed loading and receiving water models, revise calibration report (Year 1) • Downscale climate change scenarios (rainfall, temperature) (Year 1) • Leveraged Studies • Expert Panel reviews biostimulatory stress-response models (Feb 2019) • Basis for preliminary nutrient and organic matter targets • State Water Board staff scope biostimulatory policy options • SCCWRP revises biostim stress-response models (and range of potential targets) December 2019 • Completing regional flow ecology models for algae, as complement to invertebrates • Preliminary June 2019 • Revised (leveraged studies) 3 year contract; tool development year 1, model application year 2, with time for discussion with Water Board year 3 on proposed actions

17. Presentation Road Map • Overview of SMR Science Phasing and technical activities • What are we hoping to accomplish in Phase III? • Key findings for Phase II (if needed) • Next steps

18. Next Steps • Propose late February/Early March to review workplan • Establish future meetings around need to check with in TAC and SAG at critical decision points (TBD)

19. What Did We Learn in Applying Early Version of these Tools During Phase II in the Lower Main Stem?

20. Major Findings- Informing Targets for the Lower Main Stem • Range of biostimulatory targets for nutrients, organic matter from Statewide science that show adverse effects to biointegrity (invertebrate and algal community) at low threshold values • Less than RB 9 basin plan biostimulatory guidance of TN= 1 mg/L and TP = 0.1 mg/L, typically within 95th percentile of reference • Points to extreme sensitivity of Mediterranean streams to eutrophication

21. Thresholds that Impact Aquatic Life Are Extremely Low Relative to Urban/Ag Runoff and POTW Wastewater Natural Background 0.1 1 10 0.01 0.1 1 30th Percentile of Reference 10th Percentile of Reference Total Nitrogen (mg/L) Total Phosphorus (mg/L) Urban Runoff POTW Effluent Ag Runoff 1st Percentile of Reference Nutrient Pollution Biostimulatory Science

22. Major Findings- Informing Targets for the Lower Main Stem • Range of biostimulatory targets for nutrients, organic matter from Statewide science that show adverse effects to biointegrity (invertebrate and algal community) at low threshold values • Less than RB 9 basin plan biostimulatory guidance, typically within 95th percentile of reference • Points to extreme sensitivity of Mediterranean streams to eutrophication • Nutrients that are protective of current range of DO diel variability targets are less stringent than biointegrity • These DO diel variability targets have since been updated in Sutula et al. draft TR 1048 (they are lower than previously stated) • Can’t use DO objective easily because we can constrain all sources of oxygen demand in the system • Learned that benthic oxygen demand drives mean trend, which drives DO < 5 mg/L, so need to complete receiving water modeling in upper watershed to investigate

23. Major Findings- Informing Targets for the Lower Main Stem • Upper main stem typically greatly exceeded nutrient and organic matter thresholds, but generally performed better for DO • 1-2 orders of magnitude higher at MWD, RB and FB • More nuanced at the Gorge 4. Lower main stem had mixed results w.r.t. multiple lines of biostimulatory indicators protective of biointegrity: • TN and TP concentrations mostly between REF30 and REF10 • Consistent exceedances of benthic chl-a REF10 thresholds, but not by much • REF01 Exceedances of AFDM by order of magnitude or more indicative of decay and downstream transport of extensive algal blooms in Upper main stem

24. Major Findings 5. We have the right mechanistic modeling tools in place to investigate biostimulatory thresholds in the lower main stem Good calibration! 6. Investigations clarified requirements for mechanistic modeling performance • HSPF model performance would need to be optimized around predictions in the range of 0.1 – 1 mg/L TN and 0.01 and 0.1 mg/L TP to drive realistic discussions of nutrient management (this is not easy!) • Need to expand benthic algae community types to include modeling of diatoms versus soft-bodied algae (this is how you achieve high biomass in streams) • Need improved representation of algal scour and senescence (to explore seasonal objectives) • Need end-to-end Gorge to Old Hospital to explore effects of downstream transport of algal blooms from upper main stem

25. Phase II Work Elements • Statewide synthesis of science supporting biostimulatory targets • Upper river baseline monitoring report • Mechanistic model system calibration • Application of statewide synthesis and mechanistic models to investigate range of biostimulatory targets in lower River

26. What Are Biostimulatory Substances and Conditions? Eutrophication = accelerated accumulation of ORGANIC MATTER Organic Matter Dumping Nitrogen and Phosphorus Physical Habitat Alteration Hydromodification Light Temperature Water Board staff want to set NUTRIENT numeric targets, but other factors can be managed at watershed scale to reduce eutrophication

27. Scientific Basis for Biostimulatory Numeric Guidance Relies on Both Original Analyses and Existing Science Stress-Response Modeling—CA Data Benthic Chl-a, AFDM, Macroalgae % Cover, TN and TP (Aquatic Life) Existing Literature or Guidance—Global DO and pH • Existing basin plan objectives • Literature on effects of diel swings on aquatic life Macroalgal % Cover (Human Use) • Published literature on recreational user surveys (REC2) Cyanotoxins (human health): • CCHAB guidance for REC1 advisories • Pending EPA human health cyanotoxin criteria

28. RB9’s Proposed Bio-objectives No: DOES NOT MEET OBJECTIVE CSCI ≥ 0.63? Yes: MEETS OBJECTIVE Yes. CSCI ≥ 0.79? • No. CSCI between 0.63 and 0.79. • Do secondary indicators meet objectives? • ASCI ≥ 10th percentile • No toxicity • Factors that may be considered: • Lack of sufficient flow during sampling • Habitat degradation • Constraints from habitat degradation and competing uses (e.g., flood control)

29. Statewide Synthesis: Take Home Messages on CSCI-Related Thresholds • We only have ½ of the story at this point • Should have ASCI-based thresholds in ~ 6 weeks • Biostimulatory thresholds based on BCG versus reference based CSCI are equally low • Tremendous consistency in the range among western states • Below what is readily achievable WW treatment technology • Statewide, majority of stream miles meet biostimulatory thresholds defined by 30th percentile of CSCI reference sites • Within Southern California, half our stream miles are not meeting these number

30. Organic Matter (OM) Thresholds Corresponding to CSCI Endpoints Ash Free Dry Mass (Live & Dead OM) Benthic Chl-a (Live OM) CSCI Threshold CSCI Threshold BCG 1-2 BCG 1-2 11 BCG 3 BCG 3 11 BCG 4 27 Slope change 15 REF10 BCG 4 21 REF01 35 BCG 5 REF01 67 BCG 5-6 BCG 6

31. California’s Range of TN and TP Thresholds is Comparable to Other States’ Nutrient Criteria

32. Statewide, ~80% of Stream Miles Meet Thresholds protective of 10th percentile Within South Coast, Only 30 -55% Meet those thresholds TN TP AFDM Benthic Chl-a

33. Phase II Work Elements • Statewide synthesis of science supporting biostimulatory targets • Upper river baseline monitoring report • Mechanistic model system calibration • Application of statewide synthesis and mechanistic models to investigate range of biostimulatory targets in lower River

34. Quick Primer on Monitoring: River Monitoring Has Three Main Components • Bioassessment of algae • Organic matter today • Algal Taxonomy (when ASCI finalized) in lower and upper main stem • Benthic invertebrate taxonomy in upper main stem (waiting for 2017 laboratory analyses to be complete) • Monitoring of dissolved oxygen, et al. physiochemical parameters • Monitoring of discharge and nutrient concentrations • Main stem of the River • Contributing tributaries

35. SMR Sampling Sites: Upper Main Stem Water Quality Sampling to Quantify Loads Murrieta Creek Temecula Creek Gorge Above CWRMA Pipe Gorge Below Devil’s Creek MWD Crossing Rainbow Above Rainbow Creek Rainbow Below FPUD SUMP Above Sandia Creek FPUD SUMP Below SMR0 - 6 Ocean

36. SMR Main Stem Sampling Sites: Upper River Bioassessment to Quantify Biological Response Murrieta Creek Temecula Creek Gorge Above CWRMA Pipe Gorge Below Devil’s Creek MWD Crossing Rainbow Above Rainbow Creek Rainbow Below FPUD SUMP Above Sandia Creek FPUD SUMP Below SMR0 - 6 Ocean

38. SMR Sampling Sites: Lower Main Stem Upper sites SMR6 Old Hospital SMR5 SMR4 Diversion SMR3 Ysidora Gage SMR2 Below Airfield SMR1 SMR0 Ocean

39. TN and TP Concentration: Findings • TN decreased downstream of Gorge, peaking below Rainbow and Fallbrook SUMP, tapering off in Lower main stem • Spatial gradients in main stem TP not as clear cut; consistent exceedance of 0.1 mg/L TP at MWD • Tributary TN and TP explain these trends • All tributaries exceeded numeric guidance; higher exceedances in winter dry weather • extremely high TN in DC, RBC and SC; moderate in MC and TC • CWRMA release diluted higher concentrations coming from MC and TC

40. Benthic Chl-a and AFDM: Findings • Upper main stem: extremely high, chronic algal blooms throughout the year (1000s of mg chl-a /m2) • Lower main stem river: ephemeral blooms, with peaks up to 45 and 65 mg chl-a/m2 at above and below diversion, respectively; extremely high AFDM • Low C:N Ratio at Lower main stem sites tells you that this organic matter is derived algal not terrestrial C; points to upper main stem as source of high OM loading

41. Dissolved Oxygen: Findings • Despite high biomass, Gorge and MWD did not have a problem with DO, probably because of CWRMA release • Gorge– 8/8 deployments had diel amplitude< 1.4 mg/L; 8/8 had minima > 6.0 mg/L • MWD – 6/13 deployments had diel amplitude > 2 and 1/13 < 3 mg/L; 13/13> 6.0 mg/L • Fallbrook – 6/6 had diel amplitude < 2 mg/L and 5/6 > 6.0 mg/L • Problems were more evident with DO minima in Rainbow, particularly during low flow • Rainbow – 6/6 has diel amplitude ≤2 mg/L, but DO minima < 6.0 in 3/6 deployments • Lower main stem river had low diel amplitude, but larger problem with DO minima; indication that AFMD from upper main stem is contributing • Old Hospital – 2/13 deployments had diel amplitude > 2 but 6/13 had DO minima < 5.0 mg/L • Ysidora – 1/5 deployments had diel amplitude > 2 and 1/5 had DO minima < 5 mg/:

42. Biostimulatory Drivers and Mitigating Factors • Nutrient concentrations in tributaries (driver) and CWRMA (mitigating) • Organic matter loading from upper main stem (driver) • Flow (mitigating) • Perennial flow keep DO at acceptable levels • Scouring flows depress algal biomass and AFDM during winter • Channel substrate (mitigating) • Bed rock (Gorge and MWD) enhance organic matter accumulation • Sandy bottom (Fallbrook, lower main stem) discourage accumulation

43. Phase II Work Elements • Statewide synthesis of science supporting biostimulatory targets • Upper river baseline monitoring report • Mechanistic model system calibration • Application of statewide synthesis and mechanistic models to investigate range of biostimulatory targets in lower River

44. Boundary Condition (Upper Watershed) Modeling System HSPF model of upper and lower mainstem watersheds Upper River Main Stem CP Diversion MODFLOW Integration Lower River Main Stem • Receiving Water Models of Lower Mainstem • WASP (perennial) • QUAL2Kw (intermittent) CP Diversion Estuary

45. Status of the Models • HSPF updated and recalibrated • WASP and QUAL2Kw: Completed draft calibration for Lower River • All three models exhibit good calibration against observations HSPF TN Simulation

46. Solid Demonstration of Methods • All three models have potential for supporting decisions to address biostimulatory conditions in flowing waters; each have limitations • WASP is preferable to HSPF for flowing reaches due to ability to represent multiple algal types, but HSPF is easier to apply • QUAL2Kw is good choice for intermittent reaches where other models may fail – but event-based vs. continuous simulation leaves open questions about nutrient reduction scenarios • Will not have full answers until Upper and Lower mainstem nutrient responses are simulated together because much of DO problem in lower river appears due to responses in upper river

47. Second Phase of Modeling Needed in Order to Inform Biostimulatory Targets • Models can be used to predict TN and TP in the Lower River • May not be able to reliably resolve differences in decimal places • How need to have discussion about meaning of number of significant digits! • Models cannot be used currently to predict mean trend in DO, because as configured it doesn’t capture organic matter loading from upper watershed • Monitoring confirms what we see in models == organic matter deposition from upper watershed would need to be addressed meet DO objectives in Lower River • Link end-to-end receiving water model from upper main stem to lower main stem in next phase • Make refinements to capture seasonal scour from wet weather • Open opportunities for discussion of seasonal objectives • Refine modeling of benthic algal types (diatoms versus soft-bodied algae)

48. Phase II Work Elements • Statewide synthesis of science supporting biostimulatory targets • Upper river baseline monitoring report • Mechanistic model system calibration • Application of statewide synthesis and mechanistic models to investigate range of biostimulatory targets in lower River

49. Three Major Options for Establishment of Numeric Targets in Main Stem River Existing RB Basin Plan Biostimulatory Objectives Numeric Translator: TN = 1 mg/L TP = 0.1 mg/L Ranges of biostimulatory conditions linked to DO objectives Recent science supporting new biostimulatory and biointegrity policies for wadeable streams • State Water Board • San Diego Board DO objectives Process Model Biostim Targets

50. Major Findings- Informing Targets for the Lower Main Stem • Range of biostimulatory targets for nutrients, organic matter that show adverse effects to biointegrity (invertebrate and algal community) are low • Typically within 95th percentile of reference • Extreme sensitivity of Mediterranean streams to eutrophication • Nutrients that are protective of current range of DO diel variability targets are less stringent than biointegrity • Learned this morning that benthic oxygen demand drives mean trend, which drives DO < 5 mg/L, so need to complete receiving water modeling in upper watershed to investigate • Upper main stem typically greatly exceeded nutrient and organic matter thresholds, but generally performed better for DO 4. Lower main stem had mixed results w.r.t. multiple lines of biostimulatory indicators protective of biointegrity: • TN and TP concentrations mostly between BURC I/II and II/III • Consistent exceedances of benthic chl-a BURC II/III threshold, but not by much • Exceedances of AFDM by order of magnitude or more indicative of decay and downstream transport of extensive algal blooms in Upper main stem