2023-2-24-SAC Meeting Summary

NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

2/24/2023

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Attendees
SAC members in attendance:
Jim Bowen
Jud Kenworthy (SAC Co-Chair)
Jessie Jarvis
Martin Lebo
Lauren Petter
Michael O’Driscoll
Fritz Rohde
Hans Paerl (SAC Co-Chair)
Marcelo Ardon

NCDEQ staff in attendance: Note: may not have captured all DEQ staff in attendance
Rich Gannon
Chris Ventaloro
Susie Meadows (note taker)
Pam Behm
Nora Deamer
Anne Deaton
Charlie Deaton
Timothy Ellis
Karen Higgins
Paul Cough
Heather Jennings
Mark Vander Borgh
Elizabeth Kountis
Paul Wojoski
Jill Paxson
Others: Nathan Hall (UNC), Anne Coan, Clifton Bell, TJ Lynch, Andy McDaniels, Doug Durbin
SAC meeting facilitator:
Emily Barrett

Meeting notes
***All questions, comments and answers are paraphrased***
1) Convene (Emily Barrett)
• DEQ/SAC introductions
2) Recap of the SAC Charter (Emily Barrett):
• Approval of last meetings minutes: Jud motioned for approval, second from Lauren
and all in favor.
• Striving for Consensus. An option is a 5-finger voting method:
1= 100% happy,
2= I like it,
3= I can live with it,
4= I disagree & I want it noted but I’m willing to go with the group,
5= I disagree.
3) Scientific Support Document for the SAV Water Clarity Standard (Jud):
• Members need to decide if they want to comment more or approve it.
NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

2/24/2023

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o Jim: No objection, however, an alternative of 1 in 3 is not to exceed. Some
folks don’t like it that much.
o Lauren: Agree with Jim that there could be a concern about that, but the
document looked good.
o Marcelo: Also agree, but the separation between low & high salinity, not
sure if it’s in there (a definition or by reference).
o Jud: The difference between them isn’t as critical in this document as it will
be in the implementation steps.
o Marcelo: Makes sense.
o Hans: Quick clarification on thought process. It’s tied into the nutrient
criteria development process. Wanted to emphasize this is to be able to
link into criteria development.
o Jud: Comments on expectations on moving forward. Will we be involved in
implementation steps of the criteria?
o Chris: Yes, we’ll carry on the conversation of SAC providing input on
monitoring and things to consider with assessment and the nutrient criteria
development.
o Jud: Something to think about, we should have a serious discussion on low
and high salinity implementation of the criteria and unshackling them. Our
monitoring program and understanding of the abundance and status of our
high salinity SAV resource is much more advanced than it is for our low
salinity SAV resource. We have a good monitoring program established in
the APNEP partnership, to move faster with the high salinity then low
salinity.
o Jud: I think we have a consensus on the document.
o Official approvals:
• Marcelo Approve with 1
• Jim B: Approve with 1
• Rachael G: not present but communicated with Jud that she was in full
support of the document.
• Jesse: Approve with 1
• Jud: Approve with 1
• Martin: Approve with 2
• Michael: Approve with 1
• Hans: Approve with 1
• Lauren: Approve with 1
• Fritz: Approve with 1
• Wilson: not present
NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

2/24/2023

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4) Results of Albemarle-Pamlico National Estuary Partnership (APNEP) Study and
Implications to Assessment Variability: (Nathan)(Slides shown):
(Slides shown) Presenting some of the data on kPAR, looking at special and seasonal
variability throughout Albemarle-Pamlico for low salinity clarity standard. There hasn’t been a lot
of PAR attenuation measurements made. Most of the data for low salinity is from secchi disk data
collected by NCDWR and NCDMF over the last 20-30 yrs (so a lot of secchi data). But, secchi disk
depth isn’t always the best predicter of PAR attenuation. These systems that vary in color and
amount of suspended sediment they have; that variability can really throw off relationships
between secchi depth and PAR. So, it means we need real PAR attenuation data.
• We have some PAR through: EPA Coastal Condition Assessment (every 5 yr snap shot at
a few estuarine locations since 2010), ModMon (Neuse River Modeling and Monitoring
(~20 yrs, biweekly/monthly in Neuse & southwest Pamlico), a special study with APNEP
to look at PAR attenuation data (2021 & 2022, 5 station in Pamlico, 7 station in
Albemarle). And Hans and I have study going on in Albemarle, spring through fall project
looking at blooms. US Army Corp put out instruments to measure continuous PAR
attenuation with 3 years of data at 2 sites and a less data at 3 other sites.
Showing slides of APNEP/DWR special study from Chowan River and Albemarle Sound. Two lines
on the graph shown, the solid represents 1.36 /meter PAR which is the current proposed
standard for clarity (that gets 13% of PAR down to a depth of 1.5 meters). Jud requested inclusion
of a dashed line which is at 1.61/m (that gets 13% of PAR down to the depth of the median SAV
distribution that’s been measured in the low salinity areas).
The Chowan River, Alligator River and western part Albemarle Sound are going to fail these
criteria based on the data, they are well above the 1.36/m proposed criteria. The middle and
eastern part are really close to the criteria.
• Jim: Repeat what the 1.61 represents.
• Nathan: It’s the median of the measured SAV depth distribution. 50% are
shallower than that depth and 50% are deeper. Average over the whole low
salinity area.
• Jud: That line is the median detected depth distribution, the actual maximum
depth distribution is closer to the solid line in the graph shown. Gives a better feel
for the center of gravity.
• Nathan: The median depth of the SAV distribution is 1.36/m, the PAR attenuation
of 1.61/m gets you 13% of light down to 1.36 meters.
• Jim: And the 1.36 is the median of the SAV out there now, but not the median of
the depth distribution.
• Jud: right.
• Pam: These look like established station numbers, are they mid-channel?
• Nathan: Yes, they are mid-channel.
NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

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• Martin: This is a full year for 2021. If you just took data from the growing season,
how would the graph change?
• Nathan: Doesn’t change a lot. Western failing, center and eastern part meet flow
standard.
• Emily: Wanted to draw SAC member attention to the chat. From Clifton: In case my
question can be considered: As proposed, pass/fail would be based on the “worst” year in a
multi-year assessment period. Do these data give any sense of the interannual variability? Are
these maps “optimistic” since they are not necessarily based on the “worst year?
• Nathan: This is 1 year of data I’m showing now, so there’s no way to assess
interannual variability. Not sure how 2021 would stack up to other years.
Next slide: This is 2 years (2021 & 2022) of data, April through November, at 10 stations
including some tribs. Same story, western part failed, center & eastern parts are going to pass
and all the tribs will fail. In Pasquotank, Scuppernong & Alligator rivers have really high CDOM
concentrations (looks like coffee). How much is natural CDOM? Probably very high, especially
in Pasquotank, like 90%.
• Jesse: Were there any observations of SAVs with these?
• Nathan: No, the only station, at mouth of alligator river, is close to high seagrass
levels.
• Martin: The slide is indicating that 2022 has less light clarity?
• Nathan: Right, there is some variability based on the sampling date that effects
this comparison.
Next Slide: Plotted raw data versus the time of year so we can see the seasonality. The winter
may have been more turbid, late December was the clearest time of year, whereas late Jan-
Feb was worst clarity. Not a lot of seasonality.
Pamlico River shows the upper areas are meeting the criteria and the lower are not. This is 12
months of data. Then just during growing season. Neuse river looks similar, just 2021 data,
upstream stations are not meeting std, but downstream are. Some evidence of seasonality.
ModMon data 2021-2022: no strong seasonality.
Overall: the picture emerging from this data: upstream of our rivers are not meeting std, but
downstream is. Corroborates previous analysis based on KdPAR estimates from Secchi disk.
Conclusions: Upper parts of tribs currently would fail proposed clarity std. Open waters of
Albemarle Sound are borderline. Lower parts of Neuse & Pamlico will pass. Hints of
seasonality in some areas.
Continued work in collaboration with APNEP, NCDWR & ModMon to recalibrate bio-optical
model for low salinity areas and KPAR data from 2022 is coming.
• Nora: How will the model help us understand what’s happening to concentrations
in the meadows?
NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

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• Nathan: Model will help us breakdown the PAR attenuation and different
components. One way it could help understand what’s going on in the meadow
versus out in the deep water… if CDOM is the main light attenuating substance in
some of these areas, I don’t think it’s going to change in the shallow vs the deep.
That could help us know that the CDOM is the main light attenuating substance in
the shallows. We’re not sampling in the shoals/shallow areas.
• Nora: How close to an SAV bed do we have to have data for?
• Nathan: Don’t know.
• Jud: In designing the monitoring program for application to SAV there’s lots of
evidence that the meadows themselves are engineering the environment they are
living in and control the optical characteristics. Especially suspended sediments.
Going to be very important to have stations imbedded in the monitoring network
that align with stem channel stations so that we can see the effect of the SAV.
• Pam: Focusing on application of the standard, what’s appropriate, where it needs
to be monitored, how it needs to be monitored needs to be set in place first
before we start talking about assessment. Nervous we’re jumping to assessment
too quickly.
• Hans: Secchi vs PAR in Pamilco would be additionally useful.
• Nathan: Did it and can send it to you.
• Jesse: Having the water quality data without having compared SAV data only gives
half the story and especially if we’re trying to make clarity for that. In future
efforts when we’re doing this, I think need to show all of it, how it works with the
SAV.
• Nathan: Question – what happens if you go outside of the seagrass bed and
measure light attenuation and it’s terrible, then you come into he seagrass bed
and it’s great, what do you say in terms of impairment or not?
• Jesse: For a lot of water clarity standards when they are using SAV as a metric they
consider both the presence of SAV as meeting the metric and the water quality
standard also meeting the metric. Best to have inside and outside measurements.
If you have grass, there then it’s meeting the requirements of the grass. The
frequency becomes an issue.
5) Wrapping up (Jud): Challenge is in the low salinity areas, which have a compounding
factor of CDOM. Might be good to unshackle these 2 criteria. Problems seem to be
mostly in low salinity areas. When Nathan did this exercise, it was surprising and tells us
we need to move forward with higher salinity protection while working out the low
salinity issues.
6) Next Steps (Emily Barrett):
NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC)

2/24/2023

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• Next meeting is a HOLD for March 31, 2023 at 9am-12pm. Until will can assess
Staff’s availability. Right now, it is setup as virtual.
7) Closing (Emily Barrett)
8) Meeting Adjourned (Emily Barrett)