Northwest Montana News

Manganese Sampling in City Water Looking Good

In 2022 the Department of Environmental Quality (DEQ) implemented a required sampling project for Montana Public Water Suppliers to determine the prevalence of manganese in certain geographic areas throughout the state. Like calcium, manganese (Mn) is a naturally occurring element commonly found in minerals; often in combination with iron. It can be found in soil, water, air, and many of the foods we eat, like seeds and nuts. Consumed in small amounts, manganese is an essential nutrient for maintaining a healthy body, just like calcium and iron. Mn is currently regulated under secondary drinking water standards. Secondary Drinking Water Regulations (NSDWRs) set nonmandatory water quality standards for 15 contaminants. EPA does not enforce these "secondary maximum contaminant levels" (SMCLs). They are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. Although manganese is an essential nutrient at low doses, chronic exposure to high doses may be harmful. The health effects from over-exposure of manganese are dependent on the route of exposure, the chemical form, the age at exposure, and an individual’s nutritional status. EPA has recently developed a lifetime health advisory limit and DEQ has updated the State’s health –base guidance for Mn. Health advisory (HA) values can be used to evaluate the safety of your household drinking water, but because they are guidance, public water systems are not required to meet these values. The following table compares the City’s PWS December 2022 sample results with EPA and DEQ HA values. Kalispell’s results are significantly lower than the comparable HA values.

More information on manganese can be found on DEQ’s website at : Drinking Water Rules | Montana DEQ (mt.gov).

Original source can be found here.