On November 3, 2004, the states of USEPA's Region III (Delaware, Maryland, Pennsylvania, Virginia, West Virginia) met to discuss the development of nutrient criteria for lakes. The workshop was hosted by the WV Nutrient Criteria Committee held at Shepherd University, in Shepherdstown, WV.
The purpose of the workshop was to share information on developing nutrient criteria for lakes among the states of Region III, and provide critical review of the approaches taken by each state with the goal of facilitating adoption of defensible criteria. The following Powerpoint presentations were delivered:
Right click on a link to download the file to your computer. All but one of these were converted to PDF files to reduce size. For some reason, Hansen's document became vastly larger as a PDF file, so it is offered here for download as a Powerpoint doc.
Developing Nutrient Criteria for Lakes Workshop For States in Region III
Shepherd University, Shepherdstown, WV
November 3, 2004
Attendees: See log sheet below
Minutes: Gillies and Pavlick
Purpose: to share information on developing nutrient criteria for lakes among the states of Region III, and provide critical review of the approaches taken by each state with the goal of facilitating adoption of defensible criteria.
The meeting began with introductions, followed by State representatives providing brief synopses of the philosophy behind their State nutrient criteria plans. Common threads – none of the states are automatically using the USEPA proposed numbers; all are engaged in exploring cause and effect relationships (several mentioned periphyton and nutrients for streams, and DO and nutrients for lakes); VA and WV chose lakes and reservoirs as their first priority, the other states chose otherwise.
Presentations on the process and current status of nutrient criteria development for lakes were given by Maryland (Tim Rule), Virginia (Carl Zipper), and West Virginia (Martin Christ & Evan Hansen). All of the states have mostly artificial "lakes" and all are following a designated use approach to setting standards. Rather than try to summarize presentations in these minutes, they can be read in their entirety at http://www.cacaponinstitute.org/region_iii_states_lakes_meeting_11_3_2004.htm (If you don’t want to try typing all that, go to www.cacaponinstitute.org, click on NCC in the header directory, and follow the link from the WV NCC main page.)
An excellent lunch was provided by Shepherd University. Following lunch, the group identified topics of interest based on the morning’s presentations:
We then prioritized certain issues for further discussion during this meeting:
1. How to treat hypolimnetic DO:
2. Chlorophyll-a – eutrophicaion vs. fishery health & evaluating fishery vs. natural communities
3. TP vs. DO relationships
4. Our goal for the day was to determine how to express criteria for the parameters: TP, chl-a, TN, clarity
1. How to treat hypolimnetic DO:
The MD and WV presentations both discussed the issue of hypolimnetic DO, and both identified this as an issue that needed more thought. In Maryland (see presentation for details):
In West Virginia (see presentation for details):
Virginia does not address DO in their approach to setting lakes criteria. They noted that the DO-P relationship may be the wrong approach, because nutrients are not the only factor affecting DO (i.e.: DO may not be a reliable surrogate for nutrients). The Virginia approach centers on the idea that healthy fish populations indicate adequate nutrient levels.
Several noted that fish and other aquatic life can endure the low DO levels that may occur during the brief period of fall turnover, and questioned whether this time period should be an issue. It was also noted that a standard that incorporates mixing during turnover would be nearly impossible to implement. WV was not ready to concede that low DO specifically during the window of mixing may not cause harm and this question remained open.
As might be expected, the group ran through quite a number of somewhat related issues during the "hypolimnetic DO" discussion, which follow in no particular order.
How do you define natural conditions in an artificial lake? A related comment on the setting of standards for the hypolimnion provided some guidance here: Look at impoundments in sparsely populated area to determine a "reference" condition for proposed nutrient criteria parameters for a relatively "natural" lake.
One participant noted a trend of shrinking epilimnion in impoundments, but Maryland noted that the relative size of the epilimnion and hypolimnion are not nutrient related issues.
The concern was expressed that standards will become triggers for research and further study, not a preventative measure. Also, it was noted that the goal should be management to prevent a harm from occurring, rather than documenting that a harm has occurred and determining how to fix it.
VA fisheries approach incorporates Best Professional Judgement (BBJ) by fisheries biologists on a scale from 1-5 to rate fisheries. Recommend fish because they are at the top of the food chain. Underlying theory is that good fisheries should equal water quality that supports the use, in part because because fish are at the top of the food web in these ecosystems.
Comments - fish indicators should aid in setting criteria, but should not be the criteria. How do you manage a lake with multiple uses? What if having a good fishery means that the lake is not suitable, or ideal, for water contact recreation. May have to develop impoundment specific management. Research by Steve Means – of PADEP(?) – developed a fish water index- possibly did not show a relationship between fish and nutrients, he may have looked at fishable fish, trophy fish – not all species. Noted that there is a data gap for fishery and biological community data and that developing standards based off of fisheries will be a problem. This lack of data may require a collective request to EPA to extend deadlines or receive more money.
It was noted that more nutrients may result in higher daytime concentration of DO in the epilimnion, and possibly depressed DO at night – should a standard consider this?
2. Chlorophyll-a – eutrophication vs. fishery health, & evaluating fishery vs. natural communities
There is a need to address competing uses. For example, a chlorophyll a level consistent with waters that support a good bass fishery may inhibit use of those same waters for water contact recreation, and user surveys have indicated that the "public" can be quite sensitive to visual manifestations of chlor a at relatively low levels.
Chlorophyll-a criteria will be at different level for each designated use.
There are different degrees of risk for determining impairment
Variability of this parameter is an issue and would likely require a seasonal component if used for nutrient criteria. Need to develop a standardized sampling protocol that conforms to existing information on Chlor a, but the group agreed that there is currently enough data to support the use of Chlorophyll-a as a component of lake nutrient criteria.
Should criteria be designed around a statistical analysis (such as the average of some number of samples), or risk based trigger?
3. TP vs. DO relationships
Quite a few people were ambivalent about using TP in nutrient criteria, due to high variability during seasons and events; MD chose not to consider P for criteria because these issues. The group briefly discussed not using nutrients in nutrient criteria at all, depending instead on response variables. Tiffany Crawford indicated that the USEPA would be unlikely to accept this approach. There is also a need for TN and TP criteria for use in NPDES permits.
Comment- Look at TP during spring turnover to determine impairments for TMDL, choose a key sampling time.
TP ŕ chlorophyll-a ŕ impact; gets away from exact impacts
P and DO- too many other factors that make the underlying reasons for P and DO relationship unknown
The relationship of TPŕ chl-a ŕ DO in surface waters, maybe use this as a trigger
4. Expressing criteria:
Chlor-a may be the best choice for expressing criteria
Determine best matrix for variability to enforce criteria.
Use TP for NPDES and chlor-a for criteria
Chl-a ŕ TP ŕ TSI – for constructed impoundments will be affected by where samples are taken.
If TSI is used it can apply to criteria as individual component parameters or as a whole. Suggestion - use TSI to determine impairment and then backtrack to P, chl-a, for criteria.
Question: Do TSI plots take into account flushing rates. May have to re-evaluate to address impoundments, and may have to evaluate for impoundments with different flushing rates and seasonal effects.
Agreement that DO could be used for surface concentrations- whole lake concentrations.
MD has a DO model for chl-a used to estimate management.
Clarity/secchi disk- is it useable? May apply to user surveys for recreation.
TN – the group was ambivalent on the use of TN. Some felt it should not be considered for use in lakes, others felt it should at least continue to be considered. VA suggested that TN not be considered in lakes, but should be assessed in lake outflow (i.e.: receiving streams). It was noted that there are TMDLs for TN in Midwest for lakes.
Some "general thoughts" on nutrient criteria.
Comment- Nutrient standards should not use BPJ to determine impairment because it is after the fact, fixing a problem that exists rather than preventing one from occurring. Possible approach – a default high value to cover everything
Want to set standards that will protect all conditions – drought vs. heavy rain (past two years)- a risk management aspect of standards.
As part of an exchange that dealt with concerns about developing nutrient criteria based on current knowledge, the following scenario was suggested, and generally affirmed but he group:
The above discussion reflected concern in the group that the setting of nutrient criteria according to a timetable in the face of scientific ambiguity may lead to listing waters as impaired that in fact are not, and that a process should be in place to guard against this. The group was not sure if EPA will accept this approach.
Many of the possible parameters for use in nutrient criteria are sufficiently variable that the actual criteria will need to be a statistical construct of some sort, such as the average of N number of samples over X standardized period of time, a frequency of occurrence of some value, or
Comment – current databases not sufficient for lakes criteria development
Comment- Impoundments may have their own individual characteristics that can effect the lake. For example, pre- dam land use has an impact in DO.
There was a consensus that the joint meeting was an informative and valuable effort, and that these meetings should continue. All present were interested in having a second meeting in conjunction with the Mid-Atlantic Water Pollution Biology Workshop at Cacapon State Park next March. John Wirts (WVDEP) indicated he would look into this.