Protecting Groundwater Resources in St. Charles, Missouri

 It starts with safety. The safety of our customers and communities is first. No question. As we work together in collaboration with others to address groundwater resources in St. Charles, Ameren Missouri is providing this information to reinforce our commitment to ensuring water continues to remain safe in the area.

Here are the five most important things to know:

  1. Ameren Missouri is committed to the safety of all our customers and communities, including the City of St. Charles and St. Charles County. There are more than 700 Ameren co-workers who live and work in the city and county of St. Charles. We all have the same goal of ensuring clean drinking water.
  2. St. Charles officials, the Missouri Department of Natural Resources (MDNR) and the U.S. Environmental Protection Agency (EPA) have made clear that the drinking water in the City of St. Charles and surrounding communities is safe.
  3. The mission of the EPA includes ensuring that drinking water is safe and that contaminated land or water is cleaned up by responsible parties. For almost a decade, the EPA has overseen Ameren Missouri's aggressive groundwater treatment to protect the groundwater at and surrounding Ameren's Huster substation, and to protect St. Charles' well water. Ameren Missouri's continuous testing and monitoring of the surrounding groundwater is in place to ensure safe groundwater.
  4. The source of the chemical detected at City Well 6 is unknown. Ameren Missouri strongly supports additional EPA-directed testing in the area and further study of a municipal sewer line, with the cooperation of all parties. The additional testing could identify the potential source(s) of the recent low-level impacts detected at the well and whether Ameren's Missouri or other parties need to take additional action to protect groundwater and future water supply.
  5. We want to be a part of the solution for St. Charles' water infrastructure. Ameren Missouri is committed to working with federal, state and local officials to support St. Charles' efforts to secure available funding to address the city's water infrastructure needs, which is an issue common to many cities and counties facing aging infrastructure and expanding population.

Ameren Missouri is committed to preserving and protecting natural resources.
Ameren's vision is leading the way to a sustainable energy future, and stewardship is one of our key values. These principles are not just words on a page. They guide how we operate and how we interact with our customers and communities. Preserving and protecting natural resources is important for Ameren Missouri co-workers and the thousands of families that call the area home, and those who work and play in the area.

The community can be assured that St. Charles treats the well water at its water treatment plant before it is sent to residents for use, and the drinking water is safe.

The source of the low-level chemicals showing up in recent samples from one city well in St. Charles is not known. No matter the source, Ameren Missouri is committed to transparency and to working with the EPA, MDNR and the city to investigate and help identify the source. Ameren Missouri has a strong record of environmental stewardship and will continue to take actions to protect drinking water. To ensure a comprehensive investigation and conclusions based on the best available data and science, Ameren Missouri supports the EPA process, including:

  • Expanded testing of the area near City Well 6, including all possible paths the detected chemicals could be using to reach the area, including the possibility that chemicals from another location traveled to the well through the nearby municipal sewer line.
  • Investigation into the possible impacts from the polluted Hayford Bridge Road superfund (i.e., contaminated) site, also located in the area from which contaminants are known to have moved beyond the limits of the site. The EPA has been investigating and monitoring this site since 1984.
  • Continued collaboration with regulators, local leaders and third-party experts.

The current consent decree process overseen by the EPA and Department of Justice in federal District Court is transparent, provides opportunity for additional public participation, and enables continued EPA oversight of Ameren Missouri's Huster substation remediation and monitoring activities to protect the city's drinking water. Ameren Missouri supports the EPA consent decree. For nearly a decade, with oversight of the EPA, Ameren Missouri has been taking action to clean up a historical issue on company property near Huster Road and State Route 370. Ameren Missouri's actions have produced positive results, as confirmed by many years of testing by external groundwater scientists.

Since 2018, there has been public notification of the work underway and opportunity for community participation. In addition, Ameren Missouri, the City of St. Charles, the EPA and other agencies have conducted quarterly meetings to discuss the work in progress and results achieved. These meetings began nearly a decade ago, and we are committed to continued monitoring, testing and collaboration to ensure protection of the groundwater.

A separate issue facing many cities is the need to replace aging infrastructure. Like many cities in the country, the City of St. Charles' water infrastructure is aging. The region is experiencing tremendous growth. This growth increases the demand for resources, such as water, and puts additional strain on aging infrastructure. For example, Ameren Missouri is upgrading and replacing outdated equipment first installed in the 1960s and '70s.

Through August 2022, Ameren Missouri has spent at least $34 million across St. Charles city and county on completed or planned projects. These investments are improving energy reliability and creating a more resilient energy grid for customers. Many of the other vital services and resources in the area, including water infrastructure, were originally installed in the same era and may need their own upgrades to keep pace with the community's needs.

On November 17, the EPA published several documents, including a list of frequently asked questions. Key points include:

  • Water being distributed to the public after treatment at the City’s water treatment plant has regularly been sampled for volatile organic compounds (VOCs), including vinyl chloride (VC) and cis-1,2-dichloroethylene (DCE) for over 20 years, and has never shown any level of contamination. EPA has found no reason to indicate that there are any health risks posed by drinking, cooking, bathing, or otherwise using the water that is supplied by the City of St. Charles.
  • Water being distributed to the public from the City’s water treatment plant has been sampled regularly since 2008 as part of EPA’s investigations and has never shown any level of contamination of VOCs, including VC and DCE.
  • For over the past 20 years, the compliance samples collected by the City and reported to the Missouri Department of Natural Resources-Public Drinking Water Branch have not shown any detections of VOC contamination
  • Since 1987, according to the City’s website, the City has been purchasing part of their water supply from the city of St. Louis because the City’s treatment plant does not have the capacity to produce 100% of the City’s drinking water.
  • In December 2021, VOC concentrations in a monitoring well at the site (PZ-11) increased without explanation. EPA plans to perform investigative work this year to determine if the contamination in PZ-11 is related to the Ameren substation, the defunct Findett facility, or an unknown source.


Ameren Missouri supports:

  • EPA testing to verify elevated readings.
  • Expanded testing of possible contamination pathways such as a nearby municipal sewer line and impacts from the Superfund site.
  • Working with local, state and federal leaders to identify federal funds for new St. Charles City water infrastructure, which is needed regardless of testing outcomes.
  • Continued collaboration with regulators, local leaders and third-party experts to ensure water remains safe now and into the future.

Additional Resources

Updated December 9, 2022
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