Nutrient Criteria Stakeholders Agenda
8/15/2006
USGS Conference Room
Columbia MO
1:00-3:00
In Attendance: Robert Bella, HDR; Dorris Bender, City of Independence; Dale Blevins, USGS; Capala Borchelt, Table Rock Water Quality; Georganne Bowman, DNR; Cindy DiStefano, MDC; Jack Dutra, Syngenta; Steve Fischer US ACE; Ted Heisel, Washington University; Dan Obrecht, UMC; Mark Osborn, DNR; Trent Stober, MEC Water Resources; Tony Thorpe, LMVP; Chris Vitello, MDC; John Waitman, City of Springfield;
1. Dan Obrecht presented an overview of the lakes in the Ozark region (powerpoint file - 206KB), their trophic status, and applicability to proposed nutrient criteria. See presentation on lmvp.org website (Edit: file HERE).
- TSI approach vs Jones approach for classifying trophic state for the ozark reservoirs.
- Is the proposed approach for setting criteria based on current trophic state legitmate? (if the reservoir is eutrophic now is it ok to keep it eutrophic?
Group Discussion:
Mark: Oligitrophic lakes in the ozarks are found mainly in the St Francis geology. And we need to protect the whole range of uses including fisheries. Euthrophic lakes have more productivity, and therefore better fisheries.
Dale: The question becomes what do you want the lakes to be? Evaluate these on a case by case basis? If it is Euthrophic but we feel it could be mesotrophic, then we should set the criteria at that range.
Doris: Are we only looking at the protection of aquatic life?
Dan: Is the state of Missouri Fisheries healthy?
Cindy: The reservoirs with common fish kills are highly eutrhopic
Chris: during periods of time when elevated levels of Chl, and TP there have been problems. Now Table Rock may be sliding too far the other direction. There is very little fish found in the main lake (when electroshocking) But the arms are very productive, and contain many more fish. Most of the reductions in Table Rock came from upgrades to the WWTP, removing phosphorus from sewage effulent.
Tony: No one is going to mind removing sewage effluent from the waterbodies.
Ted: Can we return lakes to pre-settlement conditions (or prior to human influences)?
Doris: There isn’t pre-settlement conditions for these reservoirs. They were constructed after we changed the landscape.
Trent: When monitoring streams they had to deal with non-detects.
His equipment the detection limit is 6.25 for TP.
Mark: DNR handles non-detects this way, If the dection limit is 1, then the non-detect is recorded as .49
Dan: Back to the questions. What is the minimum number of Samples needed? Answer: 3-4 samples during the summer for at least 4 summers gives us +/-15% for phosphorous
Trent: We could reduce that number is doing Hypothsis testing. If the hypothisis is “water is unimpaired” then sampling could be less.
Dan: If we use Chl, the variability increases. Also, use of spring and fall measurements increases the variability.
Dale: Asked the group to restate why summer samples were so important.
Dan: What Statistical tests will be used? This question needs to be separated into 3 questions. How will the criteria be generated?
How will the TP values that are compared to the criteria be generated?
How will we compare the two numbers?
- We are still figuring out how to generate the criteria
- Geometric mean of 4 summer samples
- I’m not sure, but we will have to take year to year variability into account when making the comparisons.
Trent: We could use geomeans. EPA used medians. Look at the 2004-2006 303(d) methodology which used a long term record instead.
Dan: We will have to be very careful if using Secchi and Chl-A (the response variables) These are not an accurate measure of the TP in the reservoir. Also, ISS is a factor we need to consider. (It could be a substantial amount in some reservoirs). If we reduce TP, then we could see less ISS, but an increase in Chl-A and the secchi could remain the same.
Reference Lakes: Theory behind reference lakes
- You have a lake that was once oligotrophic but isn’t anymore – this lake needs to be restored
- You sample a reference lake that has not been impacted to determine the water quality in that lake, then…
- You try to get the water quality in an impacted lake to resemble the water quality in the unimpacted lake.
Why this doesn’t work in Missouri –
- Most reservoirs were built in impacted landscapes
- Many reservoirs have not shifted trophic state (eutrophic when built)
- Reservoirs age faster than natural lakes (most reservoirs have a lifespan of <100 years)
Dale: The EPA guidelines set the stage for all lakes to look like the reference lakes. But these reservoirs were built for different purposes.
2. Sampling procedures:
- Review of current field and lab methods. Georganne handed out the Quality Assurance Project Plan from the Lakes of Missouri Volunteer project. This document will be incorporated in to the final rationale to explain how the data was collected. This information can also be used as a guidance for citizen groups and others, that would like to compare water quality on a specific reservoir to the regional dataset, or change their criteria.
- What does DNR need to do when a reservoir enters the advisory level? (taking into account normal fluctuations in nutrient cause and response variables?)
3. Update on draft rule and rationale. Mark handed out the draft rationale, group discussion followed.
Trent: Where does the advisori come from? Does it need to be in the regulation? Maybe the pper and lower confidence level would be more descriptive?
Site specific Criteria – Mark will look into what we can do for attainability for the increased flushing rate in some reservoirs.
Tony: Aren't all of the values in the matrix derived from response variables?
Mark: Yes
Tony: Then wouldn't all of the values have to be recalculated, since we have decided not to use response variables?
Mark: Yes
If we change the value to Phosphorus, then the correlation between flushing and TP may be better expressed in the plains (may need to have more than two groups.)
Group decisions: It was decided to use the Jones trophic classification instead of the Carlson’s TSI approach. Mark will update the matrix with the Jones trophic states for the Ozarks. Also, the group was acceptable to using the causal variable TP as the determining value instead of the response variable Chl when setting nutrient criteria levels. Since there is a better correlation between flushing rate and TP values than flushing rate to Chl values. Mark will recalculate the values for phosphorus, and re-examine the plains reservoirs to determine if more groups are needed in the plains region (for the October meeting). In the rule framework, under protection of aquatic life, section (b) the word annual will be changed to summer seasonal .
4. Remaining schedules and benchmarks up to December.
Future meeting discussions and meeting schedule
September –
- Big Lakes – discussion on how to set criteria for multiple sites
- Revised Ozark reservoirs trophic listing and criteria.
- History and background fo rthe development of nutrient criteria (This is part of the rationale that will be submitted to the CWC and EPA.)
October –
- Big Rivers lakes (oxbows)– discussion on 1) how these will be treated 2) the pros and cons for using Nitrogen as the nutrient to monitor and reduce and 3) do we limit these by depth?
- Review of Plains region criteria – make changes to matrix as needed
- Drinking water lake criteria
- Revisions to rationale development
November –
- finalize drafts for CWC
- proposed rule – with matrix and rationale
- fiscal notes
- regulatory impact report
December –
As an aside: the stakeholders will form a workgroup to discuss how to deal with multiple sites on one reservoir (such as Table Rock) This group will meet separately from the main group and bring back any decisions/discussion to the group at large.
|
