Nitrate Contamination of Groundwater in Portage County Wells-Critique of REI Plan

(This report forwarded by Lisa Anderson). Portage County, WI has a serious problem with nitrate contamination of private water wells used by households in the rural areas subject to agribusiness activities in the “upstream” area of their groundwater. This is particularly severe in the Village of Nelsonville and the Town of New Hope areas. A group of concerned citizens has been continually pressing for some real action — that is to say, protective ordinances at County level — to strongly regulate to reduce and eliminate the nitrate contamination coming from agribusinesses in the area. This report from Dr. George Kraft, area hydrology and water quality expert, casts doubt upon the seriousness of the Land and Water Conservation Committee’s (part of Planning and Zoning Dept.) efforts to address this problem. The REI company report was presented to the County committee in an effort to show that “something is being done about this.”

January 28 2022 To:
Jen McNelly –Portage County
Steve Bradley -Portage County
Chris Holman –Portage County
Portage County Land and Water Conservation Committee

From: George J Kraft –PH, Ph.D.Subject:

REI WorkPlan would accomplish little at a large cost–improvement needed

This memorandum contains suggestions for improving the draft Groundwater Testing Work Plan submitted by REI Civil and Environmental Engineering under contract to Portage County. My comments are informed by my 40+ years of experience in hydrogeology, nitrate pollution, and monitoring network design.In brief, the REI Plan contains much competent work by a qualified contractor. But of paramount importance is this:the Work Plan, if is executed as is, will shed little light and answer few questions on the Nelsonville nitrate problem. Portage County could expend $50-$80,000 (as suggested in Option #2) and obtain little new knowledge in return.REI seems to acknowledge how little might be gained in this statement:“The placement of these [monitoring] wells will begin to assist withthe nitrate nitrate loading from private septic systems versus potential contributions from agricultural inputs.”“[W]ill begin to assist”inspires little confidence and indicates a recognition of little potential knowledge gain.1

What the County needs is a work plan that will get the job done and answer salient questions NOW rather than nibble on the edges that will kick the Nelsonville can further down the road.

Below, I suggest that the heart of the problem is a lack of well-articulated monitoring goalsand make suggestions as to what those goals might be(“A”). In “B,” I demonstrate how the proposed monitoring accomplishes little, and in “C” I suggest improvements that could help generate the knowledge that is needed to address the Nelsonville situation.Finally (D-J), I comment on other concerns and make suggestions for improvement.

Major flaw: a lack of monitoring goals

A. The work plan lacks meaningful monitoring goals.

What is Portage County trying to accomplish with monitoring?What questions is it trying to answer? Well-articulated monitoring objectives are step one in producing a good monitoring plan. Monitoring goals are completely lacking from this plan.It seems to me the responsibility for well-articulated monitoring goals belongs to the client (Portage County) and is not the fault of the consultant.I will concede that the proposal contains certain vague language that some might construe as a sort of monitoring goal, such as a Portage County goal “to develop a plan to monitor and better understand water quality…”, or a work plan goal “…to provide options through the development of a comprehensive plan to setup a groundwater monitoring well program ….”But these are not goals adequate for designing a monitoring program.

So we need well-articulated monitoring goals as a starter. Below I suggest some that reflect information “needs” previously articulated in relation to the Nelsonville nitrate problem:

1.Define nitrate concentrations and their vertical and lateral distributions in Nelsonville vicinity groundwater.

2.Define the nitrate concentrations generated by major nitrate contributing land covers in the Nelsonville vicinity.

3.Verify that improved farming practices that Gordondale suggests it is implementing might mitigate Nelsonville drinking water nitrate problems.

4.Shed light on if/how Nelsonville residents might construct new drinking water wells to obtain safe drinking water.

5.Estimate how long safe drinking water, if it exists, will last.

6.Verify previous source workon the origin of nitrate in Nelsonville wells.

7.Confirm well known groundwater flow patterns

How the plan fails

B.We need a monitoring well network (option 2)! But the proposed network will do little for advancing our understanding of the Nelsonvillesituation, and at great cost.

In the absence of well-articulated goals almost any groundwater monitoring plan might be employed. But presuming some unspoken set of goals exists, like 1-7 above, this plan mostly fails.

Most of the failure has to do with proposed monitoring well locations and the fact that wells are proposed as water table wells. What such a monitoring well network will get us is just a glimpse of what happens at the water table, but not with depth in the aquifer. The proposed network only informs well on goal 7 and only partially on goal 2 – i.e., it will inform fairly well on the groundwater quality generated in Nelsonville Village, but poorly on the other land covers.

For sake of discussion, let’s identify proposed wells in Figure 7. Those upgradient of the Village I will designate “U,” and number from NW to SE 1-4. Those downgradient of the Village I will designate “D” and also number NW to SE.

The upgradient wells, U 1,2,3 are mostly too far removed from the agricultural land cover to provide useful information on it. At best, they might give us a mix of groundwater quality resulting from woods (low nitrate) mixed with agriculture (high nitrate). Thus, a mostly failure of goal 2 when it comes to agriculture.

Frankly, if I were to bias a monitoring network to intentionally underestimate agricultural impact while attempting to appear as if I were doing something useful, this is what I would put forward.

How to fix the plan and get some much needed information

C.The problems with the plan can be fixed to make monitoring meaningful. Here’s how it could be done.

1. Move the upgradient wells to field edge to avoid a mixed-land use groundwater quality signature.

2. Monitor aquifer depth profiles that characterize whole-aquifer water quality using piezometers. I suggest a surficial screen perhaps 0-7 feet below the water table, and then 5 foot screens with 5-10 foot spacing through the remainder of the profile. THIS WOULD NOT HAVE TO BE DONE AT EVERY MONITORING LOCATION! Perhaps 1 or 2 sites each above and below gradient of Nelsonville would be

3. Possibly two or more proposed monitoring well locations could be sacrificed as cost saving measures without substantial information loss to help compensate for piezometer costs.

4. Different monitoring technology rather than 2” cased wells could be considered as a cost-saving measure. This is common in many research settings and would work well here. NR141 specifications were written for installing monitoring wells at landfills and wastewater sites (I know because I helped write it) and are not needed in this sort of setting.

Other concerns and suggestions

Use of the word “model”

Most technical folks who would be reading this document would see the word “model” and think of a groundwater flow model, a groundwater particle track model (both such as what Andrew Aslesen of Wisconsin Rural Water did), or a full blown contaminant transport model, like that performed recently for a CAFO in the vicinity of Coloma.

What REI did is an interpolation of nitrate results. In my experience this sort of work is not called a “model,” but rather a visualization or something of that nature. I’ll concede that the REI work is a “model” of sorts, specifically, a nitrate interpolation model. It appears well and good and is useful. But I strongly suggest that this be referenced as a “nitrate interpolation model” to preclude confusion that actual contaminant transport modeling was done here.

E. Nitrate Data Interpretations

The visualizations of nitrate data are useful and seem well done. As these will likely be used by political types and others without a water quality background, I am concerned that several of the representations overdrive the data, i.e., they show interpolated nitrate concentrations where no control points exist and this will mislead others. It is traditional to “blank out” such areas or, at least show isocontour lines as dashed to indicate uncertainty. For instance, in Figure B2b, below, there is a large area with no data but inferred nitrate concentrations are shown. This should be corrected.

F. High capacity wells.

We have seen here, and in the past, including in the DNR permit process, claims that high capacity wells are potential sources of confusion in the data. But none of those who invoke this hypothesized confusion bring any evidence for it. This is a topic that I looked into at one time, and did 3-D numerical MODFLOW and MODPATH modeling to investigate. What I found was that simulated irrigation wells perturb groundwater very little in the sense that it does not substantially mix aquifer water. Most flow, I found,to such wells is horizontal until very near the irrigation well. Hence little mixing occurs. I suggest dismissing high capacity wells as a confounding factor – it’s time to show evidence or banish this unsubstantiated claim.

G. The consultant’s plan diminishes the great amount of data that has been generated for Nelsonville and disparages the laudable efforts of citizen-monitoring that has been done there.

For instance, on page 3, after acknowledging that past sampling has involved 60 of 77 known wells, the text goes on to say “there was less than 34% sample participation.” This is by most standards a HUGE amount of data and GREAT participation. It would be great participation for a government agency, and is only more noteworthy that it was largely accomplished by citizen monitoring. REI wrongly casts aspersion on citizen monitoring sampling methods and the fact that county staff monitoring is consistent with citizen monitoring. This should be corrected.

H. What’s the need for groundwater age-dating?

No monitoring goal was stated for which groundwater age-dating would address. Particularly since the proposed monitoring wells are water table wells, it’s pretty safe to assume the age in them will be months to a couple years. (I can demonstrate with a pile of data if county staff want to see it.)

I have offered the county previous work that demonstrates groundwater age distributions in a setting at a nearby study quite analogous to the Nelsonville situation. That offer is still on the table. The Aslesen work as well would provide an age date approximation.Age date techniques that were relatively cheap and common in the past (e.g., CFC, SF6) have become
less useful owing to a changing atmospheric signal. (Long story there.) Tritium-He could be the only =tool available for the potential need of this project, at the cost of about $1000 per sample.

Again, what’s the goal? Then let’s see what we can do to address it.

I. The Work Plan totally neglects a key data set – the agriculture/septage source tracking. Why?

This data set, it seems to me, is an important one for consideration in designing a monitoring plan. It is as important as all the nitrate data considered by REI. Why was it neglected? This is a major deficit in the work plan.

J. Recommendation: Skip the option 3 data loggers.

“Real time” data are not necessary. Monthly or quarterly is enough. In my experience, these things are pricey, twitchy, and need regular attention. Unless new models have more proven resilience, they are more headache than they are worth. They do not obviate a need for regular chemical analysis as they require calibration and validation.

cc. Nelsonville Groundwater Committee
Other interested parties

1To be fair, REI includes “options” that would improve effectiveness of the monitoring plan. Without including the options and other improvements, the Plan will not be particularly informative.