Nutrient Objectives for San Francisco Bay: Concepts, Process and Proposed Indicators

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1 Nutrient Objectives for San Francisco Bay: Concepts, Process and Proposed Indicators Martha Sutula So. California Coastal Water Research Project Lester McKee San Francisco Estuary Institute Naomi Feger San Francisco Regional Water Quality Control Board June 29, 2011

2 Nutrient Objectives Are Coming To California Increased regulatory pressure from EPA to promulgate objectives Lawsuit settlement requires EPA to develop nutrient criteria for Florida Nutrient overenrichment increasingly seen as a problem in California Reports of increasing harmful algal blooms in lakes, stream and coastal waters State Water Board has been investing in science to support nutrient objective development

3 Overview of Talk State Water Board s conceptual approach to nutrient objectives Rationale and key tenets of approach Process to develop nutrient objectives in California estuaries Organization Steps toward developing nutrient objectives Developing nutrient objectives in SF Bay Proposed indicators, data gaps and next steps How can you get involved?

4 Nutrient Objectives Are Scientifically Nutrients are required to support life How much is too much? Direct toxicity is rarely the endpoint of interest Adverse effects occur at much lower levels Challenging Ambient concentrations can give false positives or negatives Mean chlorophyll-a concentrations relative to of mean nitrate+nitrite concentrations in SF Bay ( ; Data Source: USGS)

5 EPA Guidance Suggests Three Basic Approaches to Nutrient Objectives Reference e.g. 75 th percentile of reference waterbodies Empirical stress-response models Correlation between nutrient concentrations & response Mechanistic cause-effect models Management endpoints are based on ecological response Use model to link back to nutrient loads

6 SWRCB Staff Focusing Approach to Nutrient Objectives on Cause-Effect Cause effect approach has several advantages Direct linkage with beneficial uses More precise diagnosis of adverse effects Response indicators are more integrative than nutrients Other approaches are problematic Reference sites are unavailable for many waterbody types Stress-response can have lots of unexplained variability, spurious correlation, poor precision

7 Tenets of SWRCB s Approach Narrative objective, with numeric guidance Guidance coined as Nutrient Numeric Endpoint or NNE Diagnosis based on response indicators = NNE Assessment Framework Assessing eutrophication et al. adverse effects of nutrients Multiple lines of evidence for more robust diagnosis Algae and Aquatic Plants Dissolved Oxygen, ph

8 Tenets of SWRCB s Approach Narrative objective, with numeric guidance Guidance coined as Nutrient Numeric Endpoint or NNE Diagnosis based on response indicators = NNE Assessment Framework Assessing eutrophication et al. adverse effects of nutrients Multiple lines of evidence for more robust diagnosis Models to link response indicators to nutrients et al. factors (e.g. hydrology, climate, etc.) Can be empirical or dynamic simulation models Nutrient loads rather than ambient concentration Referred to as NNE load-response models

9 Status of NNE Development by California Waterbody Type Lakes and streams Assessment framework and models are drafted Estuaries Assessment framework under development Nearshore Coastal Habitat No work undertaken

10 Project Organization- Statewide Stakeholder Advisory Group (SAG) State Water Resources Control Board (SWRCB) Regulatory State and Regional Technical Advisory Group (STRTAG ) NNE Technical Team (SCCWRP Lead) Science Advisory Panel (SAP)

11 Project Organization- SF Bay SF Bay SAG State Water Resources Control Board (SWRCB) SF Bay Water Board STRTAG SF Bay Technical Team (SFEI Lead) Science Advisory Panel (SAP)

12 SF Bay Technical Team Roster Raphael Kudela (UC Santa Cruz) Jim Cloern (USGS) Kathy Boyer (SFSU) Richard Dugdale (SFSU) Lester McKee (SFEI) Martha Sutula (SCCWRP) Will expand expertise over time as needed

13 Process to Develop SF Bay NNE Specify geographic scope and habitat types included Develop conceptual models & identify candidate indicators Review utility of indicators vis-à-vis evaluation criteria Identify data gaps and recommended next steps to: Develop assessment framework and select endpoints Develop load-response models Establish work plan to develop the NNE in SF Bay Consensus on prioritized steps to develop NNE Identify cooperating institutions & potential funding sources

14 Geographic Scope of SF Bay NNE Scope synonymous with SF Water Board Represents transition in hydrology & salinity regime Natural boundary for development of hydrodynamic and water quality models

15 Habitat Types Considered in SF Bay NNE Framework Marsh 3 Intertidal Flats 2 Seagrass/ SAV 1 Unveg. Subtidal Include: Intertidal flats Seagrass et al. submerged aquatic vegetation Unvegetated subtidal Exclude: Emergent marsh

16 Short List of Candidate Indicators, Based on SF Bay Technical Team Review 16

17 Evaluated candidate indicators vis-à-vis review criteria Clear link to beneficial uses Predictive model to link to nutrients Scientifically sound & practical measure Reliably use to diagnose eutrophication (signal: noise acceptable) Statewide NNE Statewide NNE Candidate Indicator Candidate Indicator Review April 2011 Review April 2011 Reviewed studies to establish thresholds Identifies data gaps and next steps SF Bay NNE SF Bay NNE Literature Review Literature Review June 2011 June 2011

18 Evaluation Criteria Used to Make Distinction Among Indicator Categories Primary indicator- Will include in assessment framework Met all four review criteria (alone or in combination) High level of confidence in using to assess eutrophication Intent to develop numeric thresholds in near term Supporting indicator- May include in assessment framework Did not meet all review criteria, but may in future Supporting line of evidence Co-factor- Will not include in assessment framework Needed for interpretation, but not as part of assessment framework 18

19 Recommended Indicators : All Subtidal Habitat Primary Indicators Phytoplankton Biomass, Productivity, and Taxonomic Composition Cyanobacteria cell counts and toxin concentration Secondary Indicators Water column nutrient concentrations a and forms (C, N, P, and Si) Other HAB species cell counts and toxin concentrations Dissolved oxygen Phytoplankton 19

20 Recommended Indicators : Intertidal Habitat Primary Indicators Macroalgal Biomass and Cover Secondary Indicators Sediment % OC, N, P and particle size Microphytobenthos taxonomic composition and benthic chlorophyll a Macroalgae Microphytobenthos (MPB) 20

21 Recommended Indicators: Seagrass & Brackish Submerged Aquatic Vegetation Primary Indicators Phytoplankton Biomass Macroalgal Biomass and Cover Secondary Indicators Light attenuation Seagrass areal distribution and density Epiphyte load Seagrass Shaded By Phytoplankton Seagrass Covered by Macroalge Seagrass Covered by Epiphytes 21

22 Indicators for Tidally Muted Habitats Similar for Rest of Bay, But Endpoints May Differ Primary Indicators Macroalgal biomass and cover Phytoplankton biomass, productivity and assemblage Secondary Indicators Sediment % OC, N, P and particle size Harmful algal bloom cell count and toxin concentration Cyanobacteria cell abundance and toxin concentration 22

23 Development of the NNE For SF Bay: Literature Review and Data Gaps Analysis Recommends indicators to assess eutrophication Assesses status & trends in SF Bay using these indicators Evaluates data available to assess nutrient loads Summarizes data gaps & recommended next steps SF SFBay BayNNE NNELiterature Review June June Draft

24 Literature Review and Data Gaps Analysis: Recommended Next Steps Create a SF Bay assessment framework Develop & validate load-response models Establish nutrient loads that estuary can sustainably assimilate Develop & implement monitoring program Core monitoring: regular NNE assessments of SF Bay Special studies to develop & validate models Coordinate SF Bay NNE workplan with Delta management

25 SF Bay Water Board Seeking Stakeholder Input on NNE Workplan Prioritize recommendations from literature review and data gaps analysis Identify next steps Identify cooperating institutions Investigate potential sources of funding Linkage with RMP nutrient strategy

26 How Can You Get Involved? Scientists: Collaborate on studies to support implementation of the NNE in SF Bay Stakeholders: Join SF Bay SAG Contacts: Naomi Feger Lester McKee Martha Sutula Thank You!!