SAC Presentation - McNutt

Current and Proposed for Clarity 20230929
Considerations for Water Quality Assessment and Monitoring
Overview
2
Standards and Assessment
Integrated Report and Clean Water Act
Assessment Methods Process/History/Workflow
Considerations/Guidance/Confidence
Clarity Assessment Workflow
What happens after a “listing”
And Alternative approaches
Standards vs Assessment
3
Standards
• Science based
• Protective of uses
• Implementable in permits
• Implementable in Assessments
Assessment
• Science based?
• Guidance
• Reasonableness
• Measurement Error
• Data collection methods
• Data noise
• Considerations
Terminology
4
• Excursion- a single measure above the evaluation level
• Excursion Rate- Percent of measures above the evaluation level
• Evaluation Level- usually a numeric water quality standard
• Assessment Criteria- Excursion Rate and other considerations
• Considerations- statistical confidence, previous assessment status,
data age
• Exceeding/Meeting Criteria- result after all consideration (criteria)
decisions
• Data Inconclusive- unable to determine if meeting or exceeding
criteria
Integrated Reporting Categories
5
1
2
3
4
5
NC Impaired Waters List
303(d) List
Integrated Report
305(b) Report
EC
MC
DI
Meeting Criteria
Data Inconclusive
Exceeds Criteria
(“impaired”)
Assessment Unit (waterbody) +Parameter +Criteria Status +IR CategoryAssessment=
Brief Aside on the Integrated Report
6
A prioritized list of waters that NC needs to address per the CWA.
The assessment methods are a decision tool to make this “list”
It is not possible to determine if “USES” are being met.
Meeting Criteria for water quality standards= “supporting uses”
Tier III PAR Data Collection Methods DRAFT
7
1. Extinction coefficients shall be collected using an approved meter
2. Data will be collected within 5 meters of the deep edge of SAV area
3. Instrument shall be at least 0.5 meters off the bottom???
4. Data must be collected between March 1 and October 31 (8 months)
5. Data must be collected during at least 3 months of the above period
6. Annual growing season medians will be calculated for this period each year
Tier III data are used to inform
regulatory decisions- 303d listings.
High level QAQC.
Tier II data -High level QAQC but
used for effectiveness monitoring,
modeling- not regulatory
8
EC
N>9
>10.01% Above
Evaluation
Level
DI
2014 method gave no consideration
to “confidence” in meeting criteria
or current assessment status
MC 1
>90% Confidence
for Excursion Rate
DI
Evaluation Level= Water Quality Standard
Excursion= Over/under WQS one time
Excursion Rate > 10.01p percent
Brief Aside on Ten Percent Excursion Rate
9
• Not part of the water quality standard
• In EPA guidance as “reasonable”
• Applied to 88 parameters in NC
• 10% is science on all 88 parameters?- not 12% or 9%
Once a 10% excursion rate is used in the assessment process all
other considerations DO NOT “add” SCIENCE to the assessment
process.
10
EC 1
Listing on
2016 303(d)?
>1 excursions in
new data years
>3 excursions in
NDYs with >90%
confidence in
exceedance rate
>10.01% Above
Evaluation
Level
>90% Confidence
for Excursion Rate
N>9 >2 Excursions
in Current AP
Augmented
data to 2007
N>9 EC 3
DI 1
EC 2
DI 4
DI 2
Listing on
2022 303(d)?
Data not to
augment
>10%>90%
2 of 5
2 of 4
2 of 3
2 of 2
1 of 1Data to augment
>10%>90%
3 of 9
3 of 8
3 of 7
3 of 6
DI 3 EC 4
EC1 >10%>90% N>9 most common EC assessment
EC2 >10%>90% N<9 waterbody is already EC so at some point had N>10 therefore it will
remain EC. EC not removed due to lack of current data this could include waters with no
current data but need to continue to be EC.
EC3 >10%<90% N=NA waterbody is already EC so at some point had N>10. However
confidence is now <90% so must have 2 or more excursions in current AP to remain EC.
EC4 >10%<90% N=NA With 4 or more excursions and N<10 confidence is > 90 this
scenario goes down the other path. These will be 14-17% excursion rate
EC5 waterbody is already EC so at some point had N>10. However confidence is now
<40% so must have 3 or more excursions in current AP to remain EC.
Please Note that the >10% consideration for 88 NTE parameters is
not science but is considered REASONABLE. This is not a science-
based consideration therefore all considerations downstream do
not add more science to the decisions
In 2018 after identifying multiple “considerations” to use in making
assessment decisions. All of this is to provide “CONFIDENCE”in
the decision to LIST (EMC) (303d) or to DELIST (EPA).
EPA
EMC
EPA EPA
EMC
EPA
EPA
EPA
EMC
None of these “considerations” are in the
water quality standards that are approved by
both the EMC and EPA
11
>70% Confidence
in Meeting Criteria
MC 1
Listing on 2016
303(d)?
EC 5
<40% Confidence
in Meeting Criteria
<40% Confidence
in Meeting Criteria
>2 excursions in
new data years
>2 excursions in
new data years
DI 5
>10% Above
Evaluation Level
90% Confidence for
Exceedance Rate
LEGEND
MC
EC
DI
Meets criteria
Data Inconclusive
Exceeds criteria
Yes
No
MC 2
DI 7
DI 6
DI 8
First Pass
Assessment
EMC
EMC
EPA
EPA
EPA
EPA
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1
2
3
4
0 0.002 0.014
0.053
0.137
0.270
0.436
0.605
0.751
0.858
0.927
0.998 0.987 0.949
0.868
0.737
0.573
0.404
0.257
0.148
0.077 0.036
Assessment Statistical Model (N=60)
5 6 7 8 94 10
DATA INCONCLUSIVE
13
EC
DI
Data collected using Tier
III approved methods
MC
*Mapped SAV areas would be used as compliance point
with more site specific effectiveness monitoring data.
Data collected with secchi?
> samples for
calculation of GS median
Low Salinity Kdpar 1.36/m =13% PAR@1.5
High Salinity Kdpar 0.89/m =22% PAR@1.7
GS=March 1 to Oct 31-- 8 months
SAV presence
> X Growing Seasons in 5
year data window
Considerations for
Assessment or Monitoring
Depth of Samples
Assessment Unit Delineation
Assessment Data Window is 5
calendar years
*change Chlor a and turb standard to meet clarity “goal”
QAPP
Certifications
Current Assessment
Status
Concurrent turbidity
Concurrent chlor a
Median Ext Coef > WQS
in >0 Growing Seasons
Data collected using Tier II
approved methods
Data collected using Tier
III approved methods
DI
Tier III PAR Data Collection Methods DRAFT
14
1. Extinction coefficients shall be collected using an approved meter
2. Data will be collected within 5 meters of the deep edge of SAV area
3. Instrument shall be at least 0.5 meters off the bottom???
4. Data must be collected between March 1 and October 31 (8 months)
5. Data must be collected during at least 3 months of the above period
6. Annual growing season medians will be calculated for this period each year
15
What Happens After a Clarity Listing?
16
Excursions due to algae, TSS, CDOM or all?
chlorophyll a< 40
turbidity <25ntu
CDOM natural condition?
TMDL even possible? What does bioptical model inform?
%TN reduction to meet clarity standard
% TSS reduction to meet clarity standard
Natural conditions asmt for CDOM- ditched before 1982? or no SAV?
5R (4R) approach to address all components including SAV restoration?
New Chlorophyll a and/or turbidity standards to meet clarity goal?
How do we get to nutrient criteria with this process?