2012 Water Quality
One of the department’s responsibilities is to implement regulations to protect groundwater from pesticide and nutrient contamination. Staff identify, monitor and analyze problem areas within the state, investigate wells that exceed groundwater standards to identify potential sources of contamination, and conduct statewide sampling surveys to characterize groundwater contamination and to evaluate the effectiveness of the department’s water quality programs
Private Well Monitoring
Private Well Sampling (Exceedence Survey)
In 2012, staff collected and analyzed groundwater samples from 26 private wells that have exceeded groundwater enforcement standards to track how the pesticide and nitrate-N levels in these highly-impacted wells are changing over time. Most of these wells are in atrazine prohibition areas and most have shown declines in atrazine concentrations. As of 2012, six wells (five in Columbia Co. and one in Sauk Co.) remain above the NR 140, Wis. Adm. Code, enforcement standard (ES) for atrazine. Twenty of the 26 wells exceeded the ES (10 ppm) for nitrate-nitrogen in 2012. In 2010 staff prepared a comprehensive report presenting the results of 15 years of sampling in the Exceedence Survey.
Private Well Sampling (Targeted)
The purpose of DATCP’s Targeted Sampling Program is to collect groundwater samples from private wells in “environmentally sensitive” areas across Wisconsin and analyze those samples for nitrogen and pesticides. In addition to focusing on those that have been determined to be environmentally sensitive, the 2012 sampling effort also responded to a request for sampling support from the Adams County Land and Water Conservation Department.
A total of 77 groundwater samples were collected from 74 private wells as a part of the 2012 Targeted Sampling Program. Of the 74 private wells, nitrate nitrogen was detected above the detection limit in 54 of the wells, or in 73 percent of the wells. Additionally, nitrate nitrogen was detected above the ES in 32 of the 74 wells sampled, or in 43 percent of the wells.
Atrazine total chlorinated residues (TCR) was quantified in 15 of the 74 wells, or in 20 percent of the samples collected. This is above the predicted statewide average of 11.7 percent. Atrazine TCR was not quantified above the ES (3.0 ug/l) in any of the wells sampled. The atrazine ES includes atrazine and its three chlorinated metabolites deethyl atrazine, deisopropyl atrazine and diamino atrazine.
Metolachlor was detected in a well in Adams County at a concentration of 176 ug/l which is above the ES of 100 ug/l. DATCP is in the process of conducting a groundwater investigation in the area in an attempt to determine the source of the metolachlor. We are also working with the Wisconsin Department of Natural Resources (WDNR) and the well owner to replace the impacted well.
The two most commonly detected pesticide metabolites in the 2012 Targeted Sampling project were metolachlor ethanesulfonic acid (ESA) and alachlor ESA, which were detected in over 50 percent of the wells sampled. Metolachlor ESA and alachlor ESA were also the most common pesticide metabolites in the 2007 statewide survey, with approximately 21.6 percent of the wells having detectible concentrations. Alachlor ESA was detected in a Rock County well at a concentration of 29.7 ug/l, which is above the ES (20 ug/l). DATCP is also conducting a groundwater investigation in the area adjacent to this well.
This is the second year that neonicotinoid pesticides, including acetamiprid, clothianidin, imidacloprid, and thiamethoxam, were included on the analytical list for the Targeted Sampling Project. A very low concentration of clothianidin was detected in two wells, and imidacloprid was detected in one well.
In 2012, staff completed one groundwater investigation at a private well site that exceeded the atrazine ES. Based on information we obtained on agricultural practices in the investigation area, as well as the soil and groundwater testing performed, DATCP concluded that improper handling of atrazine near the impacted well may have contributed to the groundwater contamination. Use of atrazine on nearby fields may also have contributed, although no other wells sampled in the area showed atrazine above the ES. The results of the investigation did not support the creation of an atrazine prohibition in the area around the well.
Surface Water Sampling
Between May and October 2012, the Department, in a cooperative effort with the Department of Natural Resources, conducted a surface water sampling project to document the impact pesticide use is having on nine streams in smaller watersheds (typically 10,000 to 40,000 acres) within the Wisconsin River Drainage Basin.
A total of 52 surface water samples were collected as a part of this project, shown on this map. Of those samples, the most frequently detected compound was alachlor ESA, which was quantified in 54% of all the samples collected. The second most commonly detected compound was metolachlor ESA, which was quantified in 46% of the samples collected, followed by acetochlor ESA and atrazine, which were quantified in 23% and 17 % of the samples collected, respectively. Other pesticides detected during this project included acetochlor oxalamic acid (OA), alachlor OA, metolachlor OA, de-ethyl atrazine, and metolachlor.
Of the pesticide compounds quantified during this investigation, only atrazine was quantified during the July 2012 sampling event with a concentration greater than its EPA benchmark (acute non-vascular plant).
The results of this surface water sampling project again confirmed that low concentrations of pesticide products enter streams during or after the main pesticide application season and storm events, mainly in June and July. The results also show that low levels of pesticide metabolites, predominately metolachlor ESA and alachlor ESA, enter the stream as base flow (groundwater) independent of the timing of pesticide application or river stage. Other pesticide metabolites likely being discharged as a part of base flow include metolachlor OA, acetochlor ESA, and alachlor OA.
Monitoring Well Sampling
The primary goal of the groundwater monitoring well sampling project is to identify pesticides that have the potential to contaminate groundwater. This information is used to determine whether additional measures are needed to prevent contamination above applicable groundwater standards. The department also provides the data collected to the land owners at the well sites, the public and other state and federal agencies involved in water resource protection.
In 2012, staff collected 42 groundwater samples from 30 field-edge monitoring well sites and analyzed them for nitrate-N and pesticides of interest. Table 1 is a summary of the groundwater sample results from the field-edge monitoring well project. It shows that twelve different compounds were detected in groundwater monitoring wells, but only nitrate-N exceeded its ES. Section staff also monitored groundwater at two forest seedling nursery sites to determine if pesticides used in nursery production could cause groundwater contamination.
In 2012, DATCP staff contacted staff from the various Wisconsin County Health Departments and/or County Land and Water Conservation Departments and provided them with groundwater quality data we have collected and maintained in our “Groundwater Database”. Maps and data were provided to 12 county agencies.
In 2012 we completed the rule making process that updated all maps in Appendix A of ATCP 30, Wis. Adm. Code, using technology that was not available when the original rule was written. The updated maps became rule on May 1, 2012.
“Atrazine Use Observations” were completed within twelve Atrazine Prohibition Areas to determine if atrazine was being used in those areas. Based on these inspections, it was determined that one grower had illegally used atrazine within an atrazine prohibition area. DATCP has documented the case against the grower, and will likely take action against the grower.
Environmental Quality staff created and distributed a brochure reminding all field and vegetable crop pesticide applicators where the atrazine prohibition areas are located. These “visor cards” continue to be distributed to all commercial and private applicators in the process or renewing their pesticide certifications for 2013.
The ACM has also prepared several short educational videos that are included on the DATCP Website. These videos cover a variety of topics including protecting groundwater.
Direction for the Coming Year
We are working with the Agrichemical Technical Advisory Committee (ATAC) to discuss the possible registration of herbicide products containing isoxaflutole, which is the active ingredient in Corvus Herbicide, Balance Pro and Balance Flexx. Isoxaflutole is a selective herbicide for control of certain broadleaf and grass weeds in field corn (and potentially other crops).
Wisconsin originally denied registration of isoxaflutole in 1999 due to concerns over possible surface and groundwater contamination and effects on non-target plants. The registrant is now seeking unconditional registration of the product, and has asked DATCP to reconsider its original stand on the product based on new information. We will rely upon the ATAC to help us re-evaluate this product.
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