The glacial aquifer system underlies much of the northern United States. About one-sixth (41 million people) of the United States population relies on the glacial aquifer system for drinking water. The primary importance of the glacial aquifer system is as a source of water for public supply to the population centers in the region, but the aquifer system also provides drinking water for domestic use to individual homes and small communities in rural areas. Withdrawals from this aquifer system for public supply are the largest in the Nation and play a key role in the economic development of parts of 26 States. Corn production has increased in the central part of the aquifer system over the last 10 years, and the increased production increases the need for water for agricultural use and the need for increased use of agrochemicals. Additionally, the steady increase in population (15 million people over the last 40 years) in urban and rural areas is resulting in an increased reliance on the glacial aquifer system for high-quality drinking water. The need to monitor, understand, and maintain the water quality of this valuable economic resource continues to grow.
Major Findings
- Contaminants from geologic source—in particular arsenic and manganese—in groundwater used for drinking are a potential concern for human health
- Concentrations of nitrate and pesticides in groundwater were low in fine-grained sediment even in areas of intensive agriculture
- Chloride concentrations in groundwater are increasing in urban areas
- “Nuisance” constituents in groundwater from the glacial aquifer system could limit groundwater use
