wssc water quality monitoring for sso consent decreewssc water quality monitoring. mini-round data...

WSSC Water Quality WSSC Water Quality Monitoring for SSO Monitoring for SSO

Consent DecreeConsent Decree

Evaluation of Additional QuarterlyEvaluation of Additional Quarterly““MiniMini--RoundRound”” Monitoring ResultsMonitoring Results

December 19, 2011December 19, 2011

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WSSC Water Quality MonitoringWSSC Water Quality Monitoring

OUTLINEOUTLINE

Consent Decree BackgroundConsent Decree Background

Water QualityWater Quality Monitoring PlanMonitoring Plan

General Results SummaryGeneral Results Summary

Anacostia Results SummaryAnacostia Results Summary

MiniMini--Round Data EvaluationRound Data Evaluation

Questions / DiscussionQuestions / Discussion

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CONSENT DECREECONSENT DECREE

Requires WSSC to develop and implement a Water Requires WSSC to develop and implement a Water Quality Monitoring Plan (WQM)Quality Monitoring Plan (WQM)

Requires WQMRequires WQM to include bacterial source tracking to include bacterial source tracking (BST) (BST)

Stipulates number of BST sampling points in each sewer Stipulates number of BST sampling points in each sewer basin and minimum sampling frequencybasin and minimum sampling frequency

Anacostia watershed (8 sewer basins, 16 sampling points)Anacostia watershed (8 sewer basins, 16 sampling points)

Patuxent watershed (5 sewer basins, 8 sampling points)Patuxent watershed (5 sewer basins, 8 sampling points)

Potomac watershed (13 sewer basins, 22 sampling points)Potomac watershed (13 sewer basins, 22 sampling points)

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Water Quality Monitoring PlanWater Quality Monitoring PlanDraft WQM PlanDraft WQM Plan

Comments from AWS receivedComments from AWS received

WQM is wellWQM is well--written and wellwritten and well--consideredconsidered

Included suggestions regarding testing Included suggestions regarding testing frequency and locationsfrequency and locations

Suggestions from AWS consideredSuggestions from AWS considered

Reduce sampling points outside Anacostia watershedReduce sampling points outside Anacostia watershed

Modify sampling points within Anacostia watershedModify sampling points within Anacostia watershed

Increase frequency of sampling within Anacostia Increase frequency of sampling within Anacostia watershed and in selected sewer basins elsewherewatershed and in selected sewer basins elsewhere

Implementation of AWS suggestions would Implementation of AWS suggestions would have required modification of Consent have required modification of Consent Decree Article Two, with concurrence of all Decree Article Two, with concurrence of all partiesparties

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Water Quality Monitoring PlanWater Quality Monitoring PlanFinal WQM PlanFinal WQM Plan

As approved by MDE and EPA, the WQM As approved by MDE and EPA, the WQM Plan did not include AWS suggestionsPlan did not include AWS suggestions

WSSC offered to go beyond the MDEWSSC offered to go beyond the MDE--EPA EPA approval and conduct some additional approval and conduct some additional voluntary BST monitoring in the Anacostia voluntary BST monitoring in the Anacostia watershedwatershed

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Additional Voluntary BST SamplingAdditional Voluntary BST Sampling

WSSC offer includedWSSC offer included additional additional nonnon-- mandatorymandatory quarterly* sampling at 4 points quarterly* sampling at 4 points in Lower Anacostia areain Lower Anacostia area

44--year trial basisyear trial basis

Evaluate results and determine if further Evaluate results and determine if further quarterly sampling is neededquarterly sampling is needed

Moved one Oxon Run (Potomac) sampling Moved one Oxon Run (Potomac) sampling point to Watts Branch (Anacostia)point to Watts Branch (Anacostia)

* Two additional samples per year, conducted in quarterly periods between the regular scheduled semi-annual sampling events

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringBST Monitoring ResultsBST Monitoring Results (2007(2007--2011)2011)

Alternative presentation of results at Friends Alternative presentation of results at Friends of Sligo Creek website of Sligo Creek website www.fosc.org/Bacteria.htmwww.fosc.org/Bacteria.htm

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National BST MonitoringNational BST Monitoring

Buck Creek, TX

Lake Granbury, TX

Published 2011

1010


1111


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WSSC Water Quality MonitoringWSSC Water Quality MonitoringBST Monitoring ResultsBST Monitoring Results (2007(2007--2011)2011)Preliminary qualitativePreliminary qualitative observations:observations:

Wildlife, pets, agriculture represent 80Wildlife, pets, agriculture represent 80--100% 100% of bacteria sourcesof bacteria sources

Predominant bacterial source detected in Predominant bacterial source detected in most basins is wildlife (typ. avian/waterfowl)most basins is wildlife (typ. avian/waterfowl)

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Nine semiNine semi--annual results (20 basins)annual results (20 basins)

March and September (typ.)March and September (typ.)

Five annual results (6 basins)Five annual results (6 basins)

Additional nonAdditional non--mandatory quarterly mandatory quarterly sampling at 4 points in Lower Anacostia sampling at 4 points in Lower Anacostia area (4area (4--year trial)year trial)

June and November (typ.)June and November (typ.)

16 additional results16 additional results

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PreliminaryPreliminary observations:observations:

Human source % varies (0% Human source % varies (0% -- 36%)36%)

Human source mostly <20%Human source mostly <20%

Apparent seasonal patternApparent seasonal pattern(higher in summer / fall,(higher in summer / fall,lower in winter / spring)lower in winter / spring)

Histogram for March 2011 BST Monitoring

0

5

10

15

20

25

30

35

40

45

0% 1-5% 6-10% 11-15% 16-20% 21-25% 26-30% 31-35% 36%

Percentage of Human Source Bacteria Detected

Num

ber o

f Sam

ples

Histogram for October 2010 BST Monitoring

0

1

2

3

4

5

6

7

8

9

0% 1-5% 6-10% 11-15% 16-20% 21-25% 26-30% 31-35% 36%


Num

ber

of S

ampl

es

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringBST Monitoring ResultsBST Monitoring Results (2007(2007--2011)2011)Preliminary qualitativePreliminary qualitative observations:observations:

No apparent correlation between detected No apparent correlation between detected human source % and SSOs in same basin human source % and SSOs in same basin during prior monthduring prior month

Human source bacteria detected in basin with Human source bacteria detected in basin with no wastewater collection systemno wastewater collection system

False positive? Failing septic systems? Other?False positive? Failing septic systems? Other?

No requirement in Consent Decree to track No requirement in Consent Decree to track origin of human source fecal bacteria origin of human source fecal bacteria detecteddetected

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BST Monitoring ResultsBST Monitoring Results (2007(2007--2011) Anacostia River 2011) Anacostia River watershed, combined data from 9 sewer basinswatershed, combined data from 9 sewer basins

Anacostia Watershed BST Monitoring 2007-2011(185 samples)

66.5%

6.5% 5.9% 7.0%4.3% 3.2% 2.2% 3.2% 1.6%

0%

10%

20%

30%

40%

50%

60%

70%

80%

0% 1-5% 6-10% 11-15% 16-20% 21-25% 26-30% 31-35% 36%


Perc

enta

ge o

f Sam

ples

Anacostia Watershed BST Monitoring 2007-2011(185 samples)

67.6%

27.0%

7.0%

0%

10%

20%

30%

40%

50%

60%

70%

80%

<1 1-150 151+

Human Source Bacteria Concentrations (CFU/100mL)[Infrequent Full Contact Recreation Standard = 151 CFU/100mL]

Perc

enta

ge o

f Sam

ples

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringBST Monitoring ResultsBST Monitoring Results (2007(2007--2011) Anacostia River 2011) Anacostia River

watershed watershed –– four locations tested quarterlyfour locations tested quarterly

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringBST Monitoring ResultsBST Monitoring Results (2007(2007--2011) Anacostia River 2011) Anacostia River

watershed watershed –– four locations tested quarterlyfour locations tested quarterly

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data EvaluationRound Data Evaluation

Four years of data (2007Four years of data (2007--2010) evaluated2010) evaluated

Statistical trend analysis in order to identify Statistical trend analysis in order to identify seasonal and yearly trendsseasonal and yearly trends

Compares ability of quarterly sampling (at Compares ability of quarterly sampling (at the 4 points) versus continued semithe 4 points) versus continued semi--annual annual sampling to detect temporal trend in sampling to detect temporal trend in concentrations of both total and human concentrations of both total and human EnterococciEnterococci bacteria (ENT)bacteria (ENT)

2020

WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : ResultsRound Data Evaluation : ResultsTime series plot for Time series plot for Total ENTTotal ENT

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : ResultsRound Data Evaluation : ResultsTime series plot for Time series plot for Human Source ENTHuman Source ENT (from BST)(from BST)

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : MethodRound Data Evaluation : Method

Evaluated the incremental benefit that the miniEvaluated the incremental benefit that the mini-- rounds provide to detect changes in both Total rounds provide to detect changes in both Total and Human ENT over timeand Human ENT over time

Evaluated with statistical power analysisEvaluated with statistical power analysis

Power of the Test = probability of identifying a Power of the Test = probability of identifying a hypothetical trend (e.g., a 5% annual increase in hypothetical trend (e.g., a 5% annual increase in ENT)ENT)

Power increases with magnitude of trend, number Power increases with magnitude of trend, number of replicate samples, and number of time periods of replicate samples, and number of time periods in the monitoring data setin the monitoring data set

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Data from multiple sites combined after Data from multiple sites combined after correcting for seasonal and yearly trendcorrecting for seasonal and yearly trend

Power to detect future trend calculated Power to detect future trend calculated using patterns of variability exhibited in using patterns of variability exhibited in quarterly and semiquarterly and semi--annual dataannual data

Power to detect an annual trend level of 5% Power to detect an annual trend level of 5% computed at the 95% significance levelcomputed at the 95% significance level

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Powers from quarterly and semiPowers from quarterly and semi--annual data annual data sets are forecasted over 12sets are forecasted over 12--year monitoring year monitoring period (expected duration of Consent period (expected duration of Consent Decree water quality monitoring)Decree water quality monitoring)

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : Trend TestRound Data Evaluation : Trend TestPower to detect 5% annual trend for Power to detect 5% annual trend for Total ENTTotal ENT

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : Trend TestRound Data Evaluation : Trend Test

Total ENTTotal ENT trends : both quarterly and semitrends : both quarterly and semi-- annual sampling yields sufficient power for annual sampling yields sufficient power for trend detection (e.g., >80%)trend detection (e.g., >80%)

Quarterly sampling has marginal benefit of Quarterly sampling has marginal benefit of improved power, but diminishes from a improved power, but diminishes from a maximum benefit of 12% Year 9 to only a maximum benefit of 12% Year 9 to only a 4% benefit at Year 124% benefit at Year 12

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : Trend TestRound Data Evaluation : Trend TestPower to detect 5% annual trend for Power to detect 5% annual trend for Human Source ENTHuman Source ENT

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : Trend TestRound Data Evaluation : Trend Test

Human Source ENTHuman Source ENT trends : difference in power trends : difference in power between quarterly and semibetween quarterly and semi--annual sampling is annual sampling is negligible; neither yielding good power for trend negligible; neither yielding good power for trend detectiondetection

Low power in human source ENT due to low Low power in human source ENT due to low concentrations with high unexplained variability, concentrations with high unexplained variability, and seasonalityand seasonality

Much of the variability probably due to BST methodMuch of the variability probably due to BST method

Need trend slope of >25% to statistically detect Need trend slope of >25% to statistically detect changes in human source ENTchanges in human source ENT

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : Trend TestRound Data Evaluation : Trend TestPower to detect 25% annual trend for Power to detect 25% annual trend for Human Source ENTHuman Source ENT

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WSSC Water Quality MonitoringWSSC Water Quality MonitoringMiniMini--Round Data Evaluation : ConclusionRound Data Evaluation : Conclusion

Continued quarterly sampling at same 4 Continued quarterly sampling at same 4 points provides little benefit compared to points provides little benefit compared to semisemi--annual samplingannual sampling

MiniMini--Round Data Evaluation : Round Data Evaluation : RecommendationsRecommendations

Continue semiContinue semi--annual sampling using same annual sampling using same seasonal (spring / fall) cycleseasonal (spring / fall) cycle

Evaluate new, evolving BST human ENT Evaluate new, evolving BST human ENT methods (e.g., methods (e.g., qPCRqPCR, , BacteroidesBacteroides))

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QuestionsQuestions

ContactContact::Dr. Martin ChandlerDr. Martin ChandlerSenior ScientistSenior ScientistEnvironmental GroupEnvironmental GroupWSSCWSSC(301) 206(301) [email protected]@wsscwater.com

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