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HomeMy WebLinkAbout2024-01-26-SAC Meeting SummaryNC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 1 of 15 Attendees SAC members in attendance: Hans Paerl (SAC Co-Chair) Jud Kenworthy (SAC Co- Chair) Jessie Jarvis Martin Lebo Lauren Petter Michael O’Driscoll Fritz Rohde Marcelo Ardon Jim Bowen NCDEQ staff in attendance: Note: may not have captured all DEQ staff in attendance Elizabeth Liebig Paul Wojoski Susie Meadows (note taker) Pam Behm Karen Higgins Anne Deaton Charlie Deaton Nora Deamer Heather Jennings Mark Vander Borgh Elizabeth Fensin Dan Wiltsie Cam McNutt Tammy Hill Betsy Kountis Forest Shepherd Guests in attendance: Nathan Hall Anne Coan Clifton Bell Andy McDaniels Doug Durbin Emily Pierce Astrid Schnetzer Qubin Qin Paul Cough SAC meeting facilitator: Paul Wojoski Meeting notes ***All questions, comments and answers are paraphrased*** 1) Convene (Paul Wojoski) • SAC, DWR and guest introductions. • We have 2 meetings left and we want to focus on the Harmful Algal Bloom (HAB) questions and the relation to numeric nutrient criteria in order to protect classified NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 2 of 15 uses for these water bodies. First part of the meeting is presentations from experts to help set up and think about the 5 questions that were distributed in the agenda: 1. Is the EPA recreational criteria magnitude of 8 µg/L for microcystin appropriate for North Carolina? 2. Is the EPA recreational criteria magnitude of 15 µg/L for cylindrospermopsin appropriate for North Carolina? 3. What microcystin / cylindrospermopsin criteria levels are appropriate for swimming advisories? 4. What levels of nitrogen and phosphorus can foster the harmful algal blooms? 5. What data is needed (or questions to be answered) in order to determine the correlation between harmful algal blooms and nitrogen and phosphorus? 2) Approval of Minutes (Hans Paerl): • Jesse Jarvis made a motion to approve the minutes, Mike O’Driscoll seconded. The motion was passed unanimously. 3) NC DWR Algal Bloom Dashboard (Dan Wiltsie): presentation with slides. • Toxins produced by cyanobacteria have different health effects (liver, nervous system, skin, cell functions), however, DWR only tests for microcystins. • Important to know that the presence of toxic species does not mean there is a presence of toxins. • To look at the workflow: When blooms are reported by a resident or staff member, we sample and then ship it to our central lab in Raleigh where it undergoes analysis. If potential microcystin producers are present, we'll do some tests for that as well. Once we have all that data in, we'll update the dashboard with that information and if any follow ups are necessary and if staff are available, we'll go back out and do more sample collection to keep this process going. • Blooms can be reported online through the dashboard (NC DWR Algal Bloom Dashboard at algae.nc.gov). They fill out a survey (pinpoint exact location, can upload photos). It is an ArcGIS platform. • Blooms have been occurring in the northeastern part of the state since 2015. • 2019 Chowan bloom recorded highest value for microcystins in the area at 620 ug/L. • 90 algal bloom reports in just northeastern corner of the state since 2020; very dense along the Chowan. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 3 of 15 • Special study began in NE NC because of so many blooms there. Monthly monitoring at specific sites from May-Sept. We’ve also been monitoring at least one site every month throughout the year, not just during the summertime. • Focusing on the Dashboard Reports: o 2020 – 2 reports in Chowan (no positive microcystin results), but there were 3 positive microcystin hits in Albemarle, max concentration was 0.74 ug/L. o 2021 – 14 reports in Chowan with more in smaller creeks and ponds in the area as well. Samples in July contained 350 ug/L microcystin. EPA recommended human health recreational water quality criterion for microsystem of 8 ug/L, and a press release was issued recommending the public not go into the water or touch it. We can’t close a beach, we can only issue a statement. o 2022 – 5 reports (microcystins detected in routine samples only at 0.48 ug/L). o 2023 – 23 reports (most were from the July bloom and dominated by potential microcystin producers and detected at 1.1 ug/L, which was surprising based on the extent of and thickness of the bloom). • Showed pictures of 2 different blooms, one green and one a milky white. • Color difference is actually decaying algae. Further north the bloom began to decay and south it was still alive. o Hans: There are lots of congeners of microcystins. What do your measurements actually measure? o Dan: It’s total microcystin. o Jud: What’s the Department’s vision for this tool in the future? o Dan: Just as a monitoring and reporting tool to see where the blooms are happening across the state, but we could do more. o Hans: How many samples are collected when you see that a bloom is reported? The reason I ask that is that often these blooms are very patchy, as you know. So how do you deal with that? o Dan: That’s a great point and we have a training session at the beginning of the year to give them an idea or remind them about blooms. Our main focus is trying to get samples that are going to be in areas where folks might come into contact with them, like a place where there's a beach, a public drinking water supply. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 4 of 15 4) Chowan River Basin Water Resources Plan (Forest Shepherd) presentation with slides: • This was presented in a previous SAC meeting. • Many chapters listed in the Basin Plan. Also, one with the Pasquatank that came out at a similar time. • Chowan River was the first to show nutrient enrichment issues. Earlier reports indicated major nuisance algal blooms occurring in 1972 and 1978, and the lower portion of the Chowan River and these algal blooms were associated with fish kills and fish infective red sore disease. These nuisance algal blooms, as many of you know, are microscopic and macroscopic. Vegetation due to excess amounts of nutrients in a river system. • The nutrient sources in the Chowan River were identified as wastewater from municipal and industrial dischargers overland flow and drainage from agricultural and urban areas. • In response to this, the EMC established a Nutrient Sensitive Water Supplemental Classification in 1979 as a legal basis for controlling the discharge of nutrients, mainly nitrogen and phosphorus, into surface waters. • In 1982, the Department developed a Chowan-Albemarle Action Plan. This plan addresses the water quality problems in the area by constructing a strategic plan with specific management goals focused on the Chowan River. The implementation measures put into place to achieve those nutrient reductions mainly included converting point source dischargers to land application where possible, and the installation of best management practices for agriculture throughout the basin. • Following those efforts on the Chowan, 2002 and 2007 indicated improvements and reductions in the amount of algal blooms, intensity and frequency. • But ever since 2015, we've seen increasing algal bloom activity. • Zeroing in on the Nutrient Reduction Goals: A 30-40% reduction in phosphorus inputs and 15-25% reduction in nitrogen inputs was to achieve a chlorophyll a peak level not to exceed 40 ug/L and have a summer mean target goal of chlorophyll a concentration below 25 to 30 ug/L. NOTE: the not to exceed value of 40 ug/L is really a not to exceed value and not to have any readings above that. The goal was to make sure that we maintain chlorophyll concentrations between or below 25 to 30 ug/L. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 5 of 15 Currently we have an assessment method where we have a 10% exceedance with 90% confidence. It’s not the same kind of methodology that we assessed waters with and was envisioned back when these goals were developed. They really tried to achieve not to exceed 40 micrograms per liter target. • We have general parameters that we collect at these stations all along the Chowan. I really focused just on the consistent routine monitoring that we do up and down the Chowan. We collect nutrients and chlorophyll a at the bottom zone, sample for all of these stations up and down the river, and then we also collect phytoplankton. As Dan mentioned, we also started collecting microcystin samples in the lower section. • The data indicates a reduction in algal blooms for a while, but then picked back up. • Showed lots of pictures of algal blooms submitted by the public. • Showed graph of summer mean chlorophyll a values, peak values during 2017 and 2018. • We were focusing on the summertime frame, but now focusing on the entire time frame. We were able to look for that 75th percentile and update the graphic with our 2019 to 2020 data. NOTE: In the 2019-2022 timeframe we only had about 20 or so samples, maybe 25, whereas previously during the 2014 to 2018 timeframe we had about 40. So, it's showing a similar story, but we do have a different number of samples here, but just wanted to lay out that we're having a similar story where we're getting those higher values down in this lower section of the Chowan. And we're seeing those exceedances down here in the lower section. • Looking at upstream to downstream and looking at nutrients and how those are changing based on the 2019 to 2022 timeframe. Seeing ammonia concentrations that are generally decreasing as we go from upstream to downstream and similar with nitrate nitrite getting those lower values downstream. Very well could be response driven, increasing that TKN value. Phosphorus has a few peaks and valleys, but generally it's pretty flat. • Hopefully that gave you at least a general idea of what we're seeing in the most recent data as well as what we've presented on in the past and the River Basin plan. • Now, I definitely encourage everyone to go out and read that document, because it does lay out in detail the nutrients and the chlorophyll and algal blooms and how everything ties together as well as does a great job of describing the history of this region. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 6 of 15 o Hans: TKN has gone up over that timeframe on longitudinal graph? o Forest: Yeah, we're seeing that TKN value increase as we're going downstream. o Hans: There’s evidence that dissolved organic nitrogen inputs may be increasing as well. Inorganic nitrogen is going down, but at the same time the organic nitrogen is going up. We’re seeing this globally. We need to pay a little more attention to nitrogen. There's a pretty strong relationship there between chlorophyll increases and TKN in the system, which also would be an argument that nitrogen is really important in spurring on the increases in chlorophyll. o Jim B: On the longitudinal plot, I see ammonia and nitrate decreasing downstream, but phosphorus staying pretty much steady. That to me is indication that nitrogen might be limited in the system. o Hans: We’ll need to take a more aggressive approach to nitrogen. 5) Microcystin concentrations, congener profiles, and bacterial composition during multiple blooms in the Chowan River (Emily Pierce): presentation with slides. • Presenting some of my dissertation work on the activity in Chowan during 2019 and focusing on microcystin concentrations, congener profiles, and bacterial composition during multiple blooms. • Chowan drains into 2nd largest estuary in the US. Critical nursery habitat for many species of fish, birds, inverts. History of severe algal problems. • Showing a map of reports from 2020-2022, there’s a high occurrence of algal bloom and fish kill reports in the area. These blooms have been observed to produce microcystin, which is a concern because microcystin is a really potent hepatotoxin that targets liver cells and has been linked to death and illness in wildlife, livestock and even humans in some cases. • Microcystin can be present in several different variable forms. First it can be present in different concentrations, it can exist in over 200 slightly different structural forms known as congeners. Current management guidelines typically don't discriminate between congeners, despite differences in the toxicity and persistence in the environment. And finally, they can be present in different forms, either bound inside the cell as particulate toxin or released into the water column as dissolved toxin. Each of these factors can impact the toxicity persistence and then exposure risk of a bloom and thus potentially dictate the necessary management approaches. • A little bit more on the different phases, the dissolved versus particulate fractions can also have different human and animal exposure routes that can be important for management consideration. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 7 of 15 • Particulate microcystin (pMC) can be consumed by other organisms, including filter feeders and primary consumers. So, pMC has been integrated into animal tissues that may serve as food sources for humans or other animals and can also be ingested from scum that may form on the water surface, which is kind of a dense aggregation of these cells. • Dissolved microcystin (dMC) is a concern for dermal contact and bioaccumulation. Also, a common concern in drinking water, either from drinking water facilities or filtered by individual users. They may also potentially be aerosolized and become an inhalation risk. • With that introduction, we sought out to study how all of those varying factors in microcystin characteristics may differ during the intense blooms that occurred in 2019. • Sampling was between mid-July to early September of 2019. • Measurements made: chl-a, pMC, dMC, bacterial community composition from DNA testing. This community composition data allows us to assess which algae are present in the sample and what relative contribution they make up of that sample. These blooms were typically reported by community science groups, including the Chowan Edenton Environmental Group, and so our sampling was opportunistic. Upstream bloom sites did include measurements of microcystin and congeners. On the other hand, for the downstream site, our sampling was conducted regularly at one location, and it did include the deployment of solid phase adsorption toxin trackers or spats as we call them. These spats are essentially just small bags of resin which adsorb the dissolved microcystin out of the water column during its deployment period. These are passive time integrated tools that allow us to assess for toxin accumulation over a time period in which discrete sampling throughout that whole time period may be really difficult. • Results: chl-a were high across the sites (except for one site), the others were very different results. No correlation between biomass and microcystin; microcystin mostly in particulate form. • Looked closer at the congeners. Looked at the bacterial community with mycrocystis being dominant. • Most bloom communities showed similarities with exception of high microcystin and microcystin blooms. These blooms were at different stages of progression and ultimately degradation and when we fit a relationship across all the blooms between microcystin and microcystis, we found a strong positive exponential NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 8 of 15 relationship, indicating that microcystis abundance could be a really good molecular target for monitoring. • Downstream was different from upstream, no dominant genus within this community. • Take home message: Summer/early fall of 2019 = intense blooms, including an observation of some of the highest microcystin concentrations reported to date. And there was high spatiotemporal variability in algal biomass toxin concentrations and bacterial community across these blooms during this period, potentially related to different bloom phases. Community composition shifts from microcystis dominated communities to a community with a high abundance of bacteria associated with microcystin. Decline did indicate a bloom degradation during some of our later bloom sampling and downstream communities did not contain high abundances of either microcystis or bacteria associated with microcystis decline and may represent what we're going to consider. Microcystis may be a good molecular target for monitoring in the system. And while there was a direct link between microcystis and microcystin concentrations, the microcystin congener profiles were not different across the blooms, indicating that these genius level differences were not influencing differential congener production and the dominant congener was generally considered far less toxic and therefore container detection should potentially be built into monitoring here, especially in cases of high microcystin concentrations, to help ensure that exposure risk is being accurately estimated. And finally, there were high values of accumulated dissolved microcystin at the downstream site. We're hoping to further resolve transport, but given these current results, downstream monitoring should be triggered during upstream blooms moving forward to better understand potential transport in the system. • And we're hoping to continue this work, including analysis of environmental variables, and hopefully including some satellite imagery data during the sampling period to better resolve talks and transport potential and connectivity between these different blooms that we sampled in the system. o Hans: We’ve had some shifts in the dominant cyanobacteria, Dolichospermum - it’s a N-fixer. Does that produce microcystin as well? o Emily: We didn’t find Dolichospermum. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 9 of 15 o Elizabeth chatted: Dolichospermum tends to bloom during spring-early summer before giving way to Cylindrospermopsis and Microcystis. o Jud: What happens to microcystin in its degradation process? How much problematic chemistry is there being transported downstream and into Albemarle Sound? o Emily: It's a little bit difficult to quantify the part of your question about transport. We actually did a follow up laboratory experiment with these blooms where we brought bloom water back to the lab and incubated it for a period of up to three months and watched what happened to the toxin overtime. Granted, this is a bottle experiment. So, it could be a little bit difficult to extrapolate what we found, but we did see that particulate microcystin declined exponentially and was below regulatory thresholds within an average of I think around 20 days, but that the dissolved microcystin remained detectable for the entire length of our experiment, which was over 100 days in one case. o Hans: Also, I think what's really important whether it stays particulate or dissolved, because if it's stays in the particulate, then you could get an issue with grazers downstream. o Jud: And pathways into the food web. o Astrid: Emily’s first paper has been published and talks about the phase change between particulate and dissolved, using those blooms like she indicated, and as far as the fate goes, we're currently finalizing. A copy of the paper can be provided if needed. o Jim: Where does the Total go over time (regarding dissolved and particulate)? o Emily: Found high particulate concentrations and the dissolved disappeared. When we tracked the dissolved over time, there was actually a pretty big gap, the amount of dissolved microcystin, so presumably what was released did not make up to the amount of that initial particulate microcystin. We're assuming that there's some pretty rapid degradation of the microcystin by other bacteria in the community. o Nora: Interested in relationship between chlorophyl and the toxin. How did you sample for chl data? o Emily: They were often collected by community members reporting, likely a grab. o Astrid: We took samples from the same bottles. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 10 of 15 o Mark V.: Probably going to be grab samples, especially citizen samplers. 6) Summary of EPA’s 2019 Cyanotoxin Recommended Criteria (Paul Wojoski): • Refocus and remind the SAC of the EPA’s recommendations for human health and recreational exposure. • In 2019, EPA made recommendations for ambient water quality criteria to protect for contact recreation. • In North Carolina, both the Albemarle and Chowan are classified for primary contact recreation. Freshwater is Class B and the saline water is class SB. • The way standards work is that we have a requirement under the Clean Water Act to protect that best use of those waters. • Both B and SB denote that those waters are classified for primary recreational use, and that primary recreational use is the best use of those waters. • Criteria for 2 cyanotoxins: Microcystin 8 ug/L and Cylindrospermopsin 15 ug/L. • Could have swim advisories or create criteria. • Gave an example of how that criteria language could look (used South Carolina’s). • Want the SAC to think about these. o Jud: What’s the current feeling as to where the pendulum swings here? o Paul: That’s what we are trying to get from the SAC process. We have an algal bloom dashboard that we could use for swim advisories if that’s appropriate but, it’s hard for me to answer, except that should be the outcome of this SAC process. o Mark: All of the microcystin data/dashboard is a new approach. It's only one of the algal toxins, but it's the one that EPA has focused in on. So where are we going to go with it? It's hard to say, but the data keeps coming out. We're getting more and more data including the work that Emily and Astrid have done. That's almost doubled our knowledge of microcystin in this system and that's not done at a state level. And so, as we're collecting more and more data from not just the Chowan, but when we go to the Cape Fear, I believe, the microcystin is going to become more and more important. o Hans: Yeah, I would definitely agree with that. Maybe this could be the subject, or at least the beginning, subject of our discussions after the break. 7) Guided discussion of harmful algal blooms and cyanotoxins (Hans & Jud): • Jud: Question for Forest. What the increase downstream in total N is coming from? Given that the trends in ammonia/nitrate are going down. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 11 of 15 • Forest: Point-source reductions work pretty well. If you get the point sources out of the river basin, then you can assume it’s largely driven by non-point sources, and they are difficult to determine what they are. Don’t know. • Hans: That’s a research question that some folks are looking into. Jud, in relation to the ammonia and nitrate going down, you’re looking at a net number. You're looking at what's being put in versus what's being used by the algae, and I think it just indicates active uptake and incorporation. See a decrease in a limiting nutrient. If you look at total dissolved organic nitrogen (DON), that’s increased as much as the inorganic N is decreased. We need to know what the sources are of the organic nitrogen and then secondly, whether it's biologically used, and I know Nathan’s student has looked into that in Albemarle Sound. Looking at the uptake of DON, the net amount DON that's in the system over time. So that's a big research question that needs to be addressed and I've seen enough data now from not only our work, but others, it's largely a nitrogen limited situation. Microcystin are very rich in nitrogen. Should get serious about N-loading. • Astrid: I agree. What we found in 2019, that microcystin is the main culprit. It’s important to keep an eye on if there's a general shift over time with environmental conditions or if we're actually looking at some sort of a tipping point in regard to who plays the major role in regard to toxic events. • Hans: Asking Elizabeth, maybe you can give us some perspective on how things have changed in terms of the dominant bloom formers in different years. • Elizabeth: Haven’t noticed, but the change in temperature is noticed. When really hot you see more microcystin. • Hans: We know from the Lake Erie studies, for example, microcystin production is much higher in the spring, when the bloom first starts up, then it is later in the year. And that's been attributed to nitrogen availability. You know the blooms have plenty of everything when it first gets started. And then as nitrogen becomes more limiting, there's constraints on the amount of microcystin that's produced. We don't really know why they're producing the microcystin, but it's the case. • Emily: I think since we have single snapshot samples, it’s hard to parse that out. At the site we sampled in September, there was still really high chlorophyll, although it didn't appear that that biomass was predominantly made up of microcystis and there was very little microcystin at that point. So, for the snapshots that we did have, the 16 as copies of that gene that we used to identify microcystis did really strongly correlate with microcystin. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 12 of 15 • Nora: Look at correlations between chl and total cyanobacteria? • Hans: We do HPLC to separate different pigments of different algal groups. Yes, there’s a great deal of variability of how things change over the course of a bloom. We can have a pure microcystin bloom if you sample at the right time and there are other players there. • Astrid: There’s a historical record and we have a summary table looking at the most common culprits. Microcystin is typically there when there's any relevant microcystis concentrations. We’ll share that table when done. Question: if we think about the uses of the Chowan, recreational fishing is one and we find these toxins in some of the fish. Is the potential issue with recreational fishing and consumption of potentially toxic fish? • Hans: It’s something we can bring up as a committee. • Jud: What is the salinity tolerance of these species? What do we know about how widespread these blooms might be out in the open water? What about waterfowl and wading birds? • Hans: Salinity tolerance – we did studies a long time ago where we saw less than 8- 9 ppt salinity. When you get up in the teens then they can’t do very well, but some do very well and could replace microcystis, like anabaenopsis and others. We haven’t seen microcystis above 5 ppt. • Mark: Jud’s 2nd question – I've been promoting the satellite imaging. We can use this tool to monitor. About salinity – it gets flushed out. Blooms can move further into estuary as freshwater moves in. • Hans: that's a really good point. And I recall from the early days on the Chowan when there were really dry conditions, following the spring runoff period, the river just goes crazy, but the salinity out in Albemarle Sound is high enough to keep stuff from growing out there. So where do you want the bloom to be? Long residence times favor blooms in the rivers, but it also would enhance the salinity in the downstream waters, which would probably keep the blooms down a bit, or at least not have microcystins in there. • Astrid: Salinity in marine area and microcystins is present. Find microcystins in oysters. Fish sampled all over the Albemarle. Event-driven sampling is key. Satellite imagery is very important. • Nathan: To get a handle on the toxicity issue, will need to go to the active blooms and seeing if they're toxic is the right approach. Benthic bacteria is another issue. • Hans: That’s another can of worms. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 13 of 15 • Paul: From a regulatory standpoint, these waterbodies are classified for aquatic life protection, so the waterfowl and others should be supported. That’s based on the Clean Water Act uses of fishable and swimmable. So, it becomes a question of EPA's recommendation of 8 ug/L of microcystin will protect for human illnesses of swimmers. Does that need to be even lower to protect for the consumption of shellfish that can lead to gastrointestinal illness or something along those lines? I just want to make it clear that the protection of aquatic life is within the scope of consideration. • Lauren: Looking at it from the criteria side, do we want to go to the point of recommending that the cyanotoxin numbers are adopted into criteria? Do you want to suggest swimming advisories, or do we just use that as we think about other things. It seems like those are the kind of categories and it may come down to clarity and nutrient control versus cyanotoxin criteria. If we're thinking more about the aquatic life, but I think that's some of the stuff that we can talk about. • Hans: They are pretty interlinked. I totally agree with your take on this Paul. There’s a whole other issue with shellfish consumption. What Astrid said about the blooms and the toxin could be transported. The blooms end up dying and then into detritus on the bottom and crabs like to eat at the bottom. Can you place SPAT bags in areas of where shellfish are harvested? • Astrid: We are doing that. And got some data back that our students are working through now. Oysters and shellfish are filter feeders and great to see what’s going on in our system. • Hans: SPAT bags are a resin-based bag that looks at the accumulation of toxin. Useful as early warning. • Astrid: If you see it in the SPAT, you better look in the fish. • Mike: Has anyone worked out the relationship with riverine discharge and these events? Has it been quantified? • Hans: Good spring runoff and then go into a drought, you see the biggest blooms. • Nora: What I’m hearing is that we have some recommended recreational standards and maybe there should be some consumption standards and I'm not sure how fish tissue values versus drinking water values and how they differ. Lauren, do you have an idea? The goal is for the SAC to get to the numbers, consumption number and drinking water number in the next few meetings. NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 14 of 15 I just don't know how to go from the drinking water number to a fish consumption number but trying to bring you all back to figuring out how to monitor the system, but we still ultimately need a number that we're monitoring against. • Astrid: Just real quick, the WHO has several criteria for ingestion and total daily intake and an acute value. So, I can forward that information for microcystin. • Lauren: Thanks, Astrid. That'd be good. I don’t think there is fish tissue. I think it’s ingestion, like drinking water based. But, at a minimum, I think if there's the World Health Organization numbers, those are references that others use that are scientifically based. So, I think that's something that is available to the SAC. Upon confirming that it is just ingestion of water, not tissue consumption, then there’s the EPA numbers. • Qubin: Can we use a continuous monitoring like an index station? • Hans: I think that’s a good idea. • Qubin: Does DEQ have modeling projects for water quality to get an understanding of what happens there? Like an understanding of what happened in there and especially how the circulation or the flow is controlled to regulate the blooms. • Hans: We need to hone in on those events/times when we suspect there’s elevated microcystin. Need to get help from citizen science groups, Edenton Group is very good. • Cam: With those groups we need to manage the expectations about what we can use the data for, whether it's regulatory or not. 8) Next Steps (Paul Wojoski) • Wanted to look at Lauren’s chat of EPA’s recommendation: "The recommended magnitude represents the concentration of microcystins or cylindrospermopsin that is not expected to result in adverse human health effects from short-term recreational exposure to the toxins via incidental ingestion while swimming, based on exposure to young children." The cyanotoxin document also notes the following on shellfish and other exposures: "Although the EPA is not including other sources of cyanotoxins in this recreational exposure scenario, the Agency has included summary information on potential sources of cyanotoxins, such as drinking water, ground water, fish, shellfish, dietary supplements, air, soil, and sediments. Exposure to cyanotoxins in finished drinking water is characterized in the Drinking Water Health Advisories (U.S. EPA 2015a, 2015b). States may wish to consider these other sources of cyanotoxins in their public health approach." NC Nutrient Criteria Development Plan – Scientific Advisory Council (SAC) 1/26/2024 Page 15 of 15 • We have a recommendation from EPA, we need to decide if it’s appropriate in NC. 9) Closing/Housekeeping Remarks (Paul Wojoski/Hans Paerl) • Next meeting is March 22, 1-4pm. • The article from Bas Ibelings and Ingrid Chorus should be shared. If we can solicit any comments based on that before the next meeting, that would be good. 10) Meeting Adjourned (Paul Wojoski)