In agricultural parts of the Wisconsin Central Sands, 20-40% of drinking water wells commonly exceed the nitrate standard of 10 parts per million (as nitrate-nitrogen). In the recent news are the Village of Nelsonville, where 40% of wells exceed the standard, and the Town of Armenia, where nitrate concentrations have reached 70 (!) parts per million.
% of samples exceeding nitrate standards in some central Wisconsin Towns.
|County||Town||% Exceedence rate|
Nitrate is a form of nitrogen coming mainly from agricultural fertilizers and manure. Typical central sands crops lose half their nitrogen fertilizer to groundwater as nitrate, resulting in concentrations beneath farm fields frequently 2-5 times the standard. This is scientific fact, well known from studies dating from the 1970s to the present. The nitrate problem has grown over time with increasing amounts of chemical fertilizers and the growth of intensive agriculture that has replaced dryland farming, grassland, and forest.
The same old “cures” haven’t worked, and won’t
When the polluted Wisconsin River was cleaned up in the 1970s, regulatory approaches were used to assess how much pollution would have to be limited to make the river fishable and swimmable. Industries then were required to reduce pollution to levels consistent with that goal.
It’s different with agriculture and groundwater. No goal (such as groundwater will achieve “safe” nitrate) is stated, nor are pollution amounts limited. The nub of current approaches relies on convincing farmers to voluntarily apply nitrogen in amounts that maximize farm profit, not protect water quality. The approach is commonly called things like “Nutrient Management,” “Best Management practices,” and “University Recommendations.”
But reducing nitrogen applications to most profitable levels is insufficient to make central sands groundwater measurably better. Numerous projects have tried and failed to improve water quality this way, including the USDA Stevens Point – Whiting – Plover wellhead protection project, Tomorrow River Priority Watershed, and Port Edwards Priority Watershed. The scientific literature on these is robust.
What will it take to get cleaner water?
Cleaner water requires substantial reductions in nitrate discharged to groundwater compared to what past approaches have been able to deliver. Perhaps we can learn from the Wisconsin River experience: develop a water quality goal and then figure out what reduction would be needed to achieve it.
Getting cleaner water will not be as simple as just reducing fertilizer applications to maximum profitability levels, but the scientific literature has explored some potential options. One strategy includes averaging nitrate discharge to groundwater at a clean water goal over a rotation, combining profitable but high nitrate polluting crops with less profitable but low nitrate polluting crops. Another strategy is to utilize fertilization at suboptimum levels; for instance, a 50% reduction in nitrogen fertilization might reduce nitrate pollution by 50-90%, while reducing crop yields by only 10-20%.
But important questions need working out – if an economic hit occurs will farm businesses be expected to internalize the expense, or are governments expected make farms whole?
Beware of can-kicking…
Nitrate pollution, its causes, and the inadequacies of current nonregulatory approaches are well known and well researched. Yet we continue to advocate ineffective clean-up measures. The old adage, “The definition of insanity is doing the same thing over and over again and expecting a different result” seems to apply.
Not much new scientific knowledge is needed, rather we need to apply the knowledge that researchers have already developed over past decades to help us estimate what nitrate reductions are needed to meet groundwater goals. The science is just not all that complicated; the politics and policies of economic burden shouldering are.
Beware of the cry for more and more research and pointless measures that continually push off dealing with the issue. This old progress stifling tactic was already employed in a 1992 dismissal of stronger nitrate approaches because, “… [the industry] pours millions of dollars into objective university research.”
A few references in the remaining space
DATCP. 2018. Targeted sampling report. https://datcp.wi.gov/Documents/TargetedSamplingSummary2018.pdf . Shows water quality in selected home wells downgradient of farm fields.
Kraft, G.J. and W. Stites. 2003. Nitrate impacts on groundwater from irrigated vegetable systems in a humid north-central US sand plain. Agriculture, Ecosystems, and Environment 100:63-74. Documents failure of Best Management Practice approaches in the Port Edwards Priority Watershed and speculates on more effective measures.
Mechenich, D.J. and G.J. Kraft. 1997. Contaminant source assessment and management using groundwater flow and contaminant models in the Stevens Point – Whiting – Plover wellhead protection area. https://www.uwsp.edu/cnr-ap/watershed/Documents/contaminantsource.pdf Documents failure of Best Management Practice approaches in Stevens Point area and speculates on more effective measures.
Green Fire videos on nitrate sources and health: https://wigreenfire.org/nitrate-waters-and-health-videos/
 A relatively small amount comes from septic systems – one 40 acre central sands corn field leaches the same amount of nitrate as 120 septic systems.