Update on Numeric Nutrient Criteria Development

Transcription

1 Update on Numeric Nutrient Criteria Development Russ Frydenborg, Ken Weaver, and Denise Miller FDEP Presented by Nia Wellendorf

2 What are we doing and why? Due to adverse impacts of excessive nutrients concentrations on waterbody health and designated use attainability, EPA mandated that States adopt nutrient criteria under authority from section 304(a) of the Clean Water Act.

3 Nutrient Criteria Schedule Submitted Nutrient Criteria Development Plan to EPA - May 2002 TAC Chosen - November 2002 EPA Response to Plan - December 2002 First TAC Meeting - January Additional TAC Meetings August 2003 February 2005 Submitted revised plan to EPA - December 2003 Received Mutual Agreement on Plan - July 2004 Assembled preliminary dataset - July 2004 Goal Begin Rulemaking Process - April 2007

4 Anticipated Timeframes QA/QC review of preliminary datasets - October to November 2004 Verify spatial data Screening water quality consistent with data quality objectives to the maximum extent practicable Merge available data sources Initial nutrient data distributions (criteria) and subdivisions for Lakes and Streams(?) - First Quarter 2005 Additional data collection Intensive Statewide DO and Nutrient Monitoring Plan February 2005 through January 2006 Continued refinement and review of subdivisions - ~March 2005 through April 2007(?)

5 US EPA Guidance Using Reference Waterbodies to Establish Criteria One approach that may be used in developing criteria is the reference reach approach. Reference reaches are relatively undisturbed stream segments that can serve as examples of the natural biological integrity of a region. Because it can be argued that most, if not all, lakes have been impacted by human activity to some degree, reference conditions realistically represent the least impacted conditions or what is considered to be the most attainable conditions.

6 US EPA Guidance Defining Reference Condition Natural vegetation has a positive effect on water quality and hydrological response of streams. Reference lakes could be chosen from watersheds that have an established minimum percentage of existing natural vegetation cover, such as 50 percent or more. Alternatively, reference criteria could be defined as less than a certain percentage of urban or residential land use in the watershed.

7 Overview of DEP Proposed Nutrient Criteria Development Approach Inventory Data and screening according to data quality objectives Identify reference lakes and streams based on LDI<2 and BPJ Use data from reference waterbodies to statistically derive numeric criteria Use statistical models to determine subdivisions of natural waterbodies Statistically describe reference condition Percentiles Geometric mean Define appropriate assessment methodologies (compliance tests) Iterative process initially based on found data with subsequent verification through directed studies

8 Stream Bio-regions of Florida 65f 65g 75a 65h 75e 75f Northeast Panhandle 75c Southeastern Plains Ecoregion (#65) 65f Southern Pine Plains and Hills 65g Dougherty/Marianna Plains 65h Tifton Upland/Tallahassee 75d Peninsula Southern Coastal Plains Ecoregion (#75) 75a Gulf Coast Flatwoods 75b Southwestern Florida Flatwoods 75c Central Florida Ridges and Uplands 75d Eastern Florida Flatwoods 75e Okeefenokee Swamps and Plains 75f Sea Island Flatwoods Southern Florida Coastal Plains Ecoregion (#76) 76a Everglades 76b Big Cypress 76c Miami Ridge/Atlantic Coastal Strip 76d Southern Coast and Islands 75b 76b 76d 76a 76c

9 Florida Level III Lake Ecoregions Ecoregion 65 Ecoregion 75 Ecoregion 76

10 Status of Data Inventory Modernized Storet with additional data elements MDLs Lab and analytical methods Analysis date Qualifier codes still an issue; i.e., screening Legacy Storet IWRM USGS SFWMD DBHYDRO SWFWMD Ambient Lakes data Other sources may be available

11 Lake LDI Calculation Results (from NHD coverage) Number of Lakes LDI <2.0 (Reference) 100 m 500 m Buffer Buffer LDI < LDI < Total* *Additional lakes added since May 2004 run, including all lakes over 50 Acres

12 Location of Reference Lakes with FL STORET Nutrient Data Collected in the Past 10 Years

13 The Biological Condition Gradient Biological Condition Natural structure and function of biotic community maintained 1 2 Major changes in structure & moderate changes in function Minimal changes in structure & function Minimally Disturbed Reference Conditions 3 Evident changes in structure and minimal changes in function 4 Moderate changes in structure & minimal changes in function 5 Severe changes in structure & function 6 Increasing Effect of Human Activity

14 DEP Proposed Reference Site Approach LDI Index A Quantitative Measure of the Intensity of Human Landscape Uses Least Disturbed Reference Sites Count Nutrient Concentration (µg/l) Characterize Reference Condition Proportion per Bar

15 Characterizing Reference Condition Reduce or explain variance Define distinct populations Central tendency Variance Find significant relationships Count Nutrient Concentration (µg/l) Univariate or Multivariate Analyses Proportion per Bar Count Proportion per Bar Count Proportion per Bar Count Proportion per Bar Count Proportion per Bar Nutrient Concentration (µg/l) Nutrient Concentration (µg/l) Nutrient Concentration (µg/l) Nutrient Concentration (µg/l)

16 Univariate Example Testing Central Tendency and Variance 3 Ln(TP) Standard Deviation ± 95% C.I. (µg/l) Sub-Ecoregion Ln Total Phosphorus (µg/l) Sub-Ecoregion Homogeneity of Variance Test Bartlett's Test Test Statistic: P-Value = Test for Equal Central Tendency ANOVA (means) excluding 65-06: p<0.001 Kruskall-Wallis (medians): p<0.001

17 Multivariate/Data Reduction Analyses Principal Components Analysis SWFWMD Ambient Lakes Data Factor Loading Plot Lakes in Ordination Space PH ALKALINITY CHLA 6 4 Acid Clear Acid Colored Alkaline Clear Alkaline Colored FACTOR(2) 0.0 SECCHI TP COLOR PCA Axis FACTOR(1) PCA Axis 1

18 Numeric Criteria Derivation Long-term level required to preserve least disturbed reference condition Use data from reference waterbodies Waterbody type specific Statistically describe reference condition; e.g., Percentiles Geometric mean Medians Criteria could include Averaging periods Frequencies Seasonal adjustments Frequency Potential Criteria Mean ± 90% C.I. 75th Percentile 90th Percentile Nutrient Concentration (µg/l)

19 Ambient Assessment Methodology Designed to test the achievement of the criteria given natural and sampling variability Should consider both type I and type II statistical errors Limiting nutrient consideration Biological assessment provision; i.e., validate imbalance status using biological response variables SSAC provision Possibly incorporated into the IWR

20 Reference Distribution Mean ± 90% C.I. 75th Percentile 90th Percentile Ambient Assessment Impaired Condition Methodology Assess variability above the criterion Balance type I and II errors Frequency Nutrient Concentration (µg/l)

21 Considerations Although nutrients have potential to cause imbalances in streams, other factors influence biota A percentile distribution model may be subject to some degree of false positives Exceedances should be validated with biological data or visual evidence of imbalances Russ Frydenborg

22 Preliminary Analysis of IWRM STATUS Network Cycle 1 Lakes Data Denise Miller & Amy Wheeler Nutrient TAC meeting August 4, 2004

23 IWRM Lakes Data Evaluation 1. Assemble Dataset for identified minimallydisturbed sites Nutrient Data Factors for examination of potential subclassifications (e.g., Ecoregion) 2. Conduct and Describe Data Quality Assessment 3. Investigate multivariate models for determining potential subdivisions of natural lakes 4. Describe Relevant Statistic from Nutrient Data to Serve as Possible Criteria 5. Corroboration through Stressor-Response Approach

24 Screened Sample Data LDI < 2.0 Lakes* Parameter N Unscreened N Post Screen % Rejected orthop % TP % Ammonia % TKN % NO2NO % Turbidity % Alkalinity % Specific Conductivity, Field % Specific Conductivity, Lab % Color % Dissolved Oxygen % ph % Chlorophyll-a % * Excluding marine-influenced lakes, borrow pits, BPJ exclusions

25 Lake-Level Data Matrix LDI < 2.0 Lakes* 148 Minimally-Disturbed Lakes Screened data condensed into a matrix with one value, median, for each parameter for a lake Majority of lakes (~75%), sample N = 1 So, lake median usually one sample * Excluding marine-influenced lakes, borrow pits, BPJ exclusions

26 Some Preliminary Analyses Parameter N 25th Percentile Median Mean 75th Percentile 90th Percentile TP (mg/l) TN (Calculated; mg/l) Ammonia (mg/l) TKN (mg/l) Nitrate + Nitrite (mg/l) Chl a (ug/l) Turbidity (NTU) Summary Statistics based on IWRM Cycle 1 Reference Lakes Medians, screened data N = Number of reference lakes for each parameter

27 Preliminary IWRM Level III Lake Ecoregion TP Summary Level III Ecoregion N 75th Percentile (mg/l) 90th Percentile (mg/l) All Summary Statistics based on IWRM Cycle 1 Reference Lakes Medians, screened data

28 Preliminary IWRM Level III Lake Ecoregion TN Summary Level III Ecoregion N 75th Percentile (mg/l) 90th Percentile (mg/l) All Summary Statistics based on IWRM Cycle 1 Reference Lakes Medians, screened data

29 Preliminary IWRM Level III Lake Ecoregion Chl a Summary Level III Ecoregion N 75th Percentile (ug/l) 90th Percentile (ug/l) All Summary Statistics based on IWRM Cycle 1 Reference Lakes Medians, screened data

30 Screening on Qualifier Codes Data Rejected for: F IWRM project qualifier for failed field QC J estimated value K actual value is known to be less than the value given O sampled but analysis lost or not performed Q holding time exceeded Y not properly preserved Data Sometimes Rejected for: L actual value is known to be greater than the value given Rejected unless qualifying a Secchi Depth value. This remains an unresolved issue for Secchi Depth. V blank contamination Reviewed further. (See Screening on Blank Data slide.)

31 Screening on Qualifier Codes, continued Data Not Rejected for: A average of one or more results I value between MDL and PQL Value Substitution: U below MDL U-qualified data were substituted with ½ x MDL value

32 Screening on Blank Data U-qualified (<MDL) data associated with a contaminated blank were not rejected For values >MDL, data <5x contaminated blank concentration were rejected For values >MDL, data >5x contaminated blank concentration were not rejected V-qualified data (indicating blank contamination) with no U qualifier and no associated blank concentration information were rejected

33 Screening on Comments Data Rejected for these Comments: Matrix spike recovery was outside the control limits Laboratory fortified blank recovery was outside the control limits Holding time issues Preservation issues ph out of acceptable range (ph rejected) DO out of acceptable range (DO rejected)

34 Screening for Reversals Phosphorus: If TP and op were both >PQL, reject both if op > 1.2xTP If either TP or op <PQL, reject both if op >MDL and op > 1.3xTP Nitrogen: If TKN and ammonia were both >PQL, reject both if ammonia > 1.2xTKN If either TKN or ammonia <PQL, reject both if ammonia >MDL and ammonia > 1.3xTKN

35 Preliminary Analysis Provisional analyses Modernized Storet (FL Storet) Lake data Reference designation based on LDI only ½ MDL replacement No qualifier or QA screening

36 Preliminary Data Distribution of FL Storet Total Phosphorus For All Lakes LDI<2.0 Original Scale Natural Log Count Total Phosphorus (µg/l) Proportion per Bar Count Ln Total Phosphorus (µg/l) Proportion per Bar

37 Preliminary Data Distribution of Annual Median Lake TP and Mean Natural Log Transformed Lake TP Median For All Lakes LDI<2.0 Mean Ln TP Count Proportion per Bar Count Proportion per Bar Median Annual TP (µg/l) Mean Annual Ln Total Phosphorus (µg/l)

38 Preliminary Lake Ecoregion Total Phosphorus (µg/l) Summary Lakes LDI < 2 Level III Ecoregion N Geometric Mean Upper 90% Confidence Level of the Geometric Mean 75 th Percentile Annual Lake Median 90 th Percentile Annual Lake Median Overall

39 Nutrient Criteria Development Website Links to Related Materials htm EPA Guidance EPA Ecoregion Recommendations Clean Water Act Survey of States, Tribes and Territories Nutrient