The need for increased testing of private wells is one of the findings in the annual report of the Groundwater Coordinating Council (GCC), which was released last week.
Nearly three-quarters of Wisconsin residents rely on groundwater as the primary source for their drinking water and the report aims to further public understanding of groundwater quality and quantity as well as the need for ongoing research into the factors that affect groundwater supplies. This year’s report encourages broader testing of private wells and notes areas of the state where progress is being made to reduce nitrate levels.
The Groundwater Coordinating Council was formed in 1984 to help state agencies coordinate activities and exchange information on groundwater. Today, the council and its subcommittees regularly bring together staff from more than 10 different agencies, institutions and organizations to communicate and work together on a variety of issues.
Patrick Stevens, administrator for the Wisconsin Department of Natural Resources’ environmental management division and chairman of the Groundwater Coordinating Council, said the group’s work reflects the need for coordination in managing the resource in Wisconsin. In addition to supplying homes and supporting businesses, Wisconsin’s groundwater also provides critical habitat through spring-fed rivers, lakes and streams.
“Wisconsin’s groundwater helps anchor the state’s economy and is fundamental to a healthy environment,” Stevens said. “The Groundwater Coordinating Council’s report helps identify next steps to protect and preserve our valuable groundwater resources.”
Here are some of the findings from the 2016 report:
Nitrate: Nitrate is Wisconsin’s most widespread groundwater contaminant and is increasing in extent and severity. Nitrate levels in groundwater above 2 milligrams per liter (mg/L) indicate a source of contamination such as agricultural or turf fertilizers, animal waste, septic systems and wastewater. Approximately 90 percent of total nitrate inputs into our groundwater originate from agricultural sources. Up slightly from the previous year, 57 public water supply systems exceeded the nitrate drinking water standard of 10 mg/L in 2014, requiring them to post notices, provide bottled water, replace wells, install treatment or take other corrective actions. Concentrations of nitrate in private water wells have also been found to exceed the standard.
Bacteria, viruses and other pathogens: Bacteria, viruses, and other pathogens often occur in areas where the depth to groundwater is shallow, in areas where soils are thin, or in areas of fractured bedrock. These agents can cause acute illness and result in life-threatening conditions for young children, the elderly and those with chronic illnesses. In one assessment, approximately 23 percent of private well water samples statewide tested positive for total coliform bacteria, an indicator species of other biological agents. Approximately three percent of these wells tested positive for E. coli, an indicator of water borne disease that originates in the mammalian intestinal tract. Research conducted at the Marshfield Clinic indicates that 4-12 percent of private wells contain detectible viruses. Public and private water samples are not regularly analyzed for viruses due to the high cost of the tests.
Pesticides: Pesticides are estimated to be present in one-third of private drinking water wells in Wisconsin from field applications, pesticide spills, misuse or improper storage and disposal. The most commonly detected pesticide compounds in Wisconsin groundwater are atrazine and metabolites of atrazine, alachlor and metolachlor.
Arsenic: Naturally occurring arsenic has been detected in wells throughout Wisconsin. DNR historical data show that about 4,000 public wells and more than 3,000 private wells have detectable levels of arsenic. About 10 percent of these wells exceed the federal drinking water standard of 10 µg/L. Although arsenic has been detected in well water samples in every county in Wisconsin, the problem is especially prevalent in northeastern Wisconsin where increased water use has likely released arsenic from rocks and unconsolidated material into the groundwater.
The GCC came up with a list of priority and ongoing recommendations for Wisconsin waters, as well as emerging issues that threaten our waters.
- Evaluate the occurrence of viruses and other pathogens in groundwater and groundwater-sourced water supplies, and develop appropriate response tools.
- Implement practices that protect groundwater from nitrate and other agricultural contaminants.
- Support the sustainable management of groundwater quantity and quality in the state to ensure that water is available to be used, which will protect and improve our health, economy, and environment now and into the future.
- Support implementation of the Statewide Groundwater Monitoring Strategy. Chapter 160 of the Wisconsin Statutes requires the DNR to work with other agencies and the GCC to develop and operate a system for monitoring and sampling groundwater to determine whether harmful substances are present (s. 160.27, Wis. Stats.).
- Continue to catalog Wisconsin’s groundwater resources. Management and protection of Wisconsin’s groundwater resources requires publicly accessible and up-to-date data in order to foster informed decisions.
- Continue to support applied groundwater research. Focus on investments to identify and test cost-effective groundwater protection strategies that can prevent groundwater problems before they need to be remediated at a much greater cost.
- Industrial sand mining. Since 2010, unprecedented growth of industrial sand mining and processing has occurred in West-Central Wisconsin and is expected to continue growing for another decade. The potential impact of this industry on groundwater resources has not been comprehensively evaluated, which would be the first step to avoid problems and plan for restoration. Wisconsin should support data analysis and field investigations to understand how this industry might impact groundwater.
- Livestock industry expansion. Since 2010, many animal feeding operations that house thousands of animals have been sited or proposed in Wisconsin. These operations require large quantities of groundwater for both animals and animal food crops, and must also dispose of large amounts of animal waste. Wisconsin agencies should develop efficient and effective ways for measuring groundwater quality and quantity conditions in and around these operations.
- Effects of extreme weather. More prolonged drought or heat waves can increase groundwater demand at the same time as reducing supply. Groundwater quality may be affected by large fluctuations in water table elevation that can occur with extreme weather.
- Metallic mining. Lead, zinc, iron and copper deposits exist around Wisconsin. These deposits may be mined in the future and are located in sparsely populated regions where background information on groundwater resources is often incomplete. The state should support background data collection and groundwater assessments so that future decisions about potential mining operations can be made most efficiently.