FACTS ABOUT GROUNDWATER

• There are an estimated 2.8 million trillion gallons of groundwater, 30.1 percent of the world’s freshwater. 
• An estimated 79.6 billion gallons of groundwater is withdrawn daily, or 26 percent of the water withdrawn in the U.S.
• From 2010 to 2015, groundwater use in the United States increased by 8.3% while surface water use declined by 13.9%.
• About a quarter of all U.S. rainfall becomes groundwater.
• Hydrologists estimate U.S. groundwater reserves at 33,000 trillion gallons, equal to the amount discharged into the Gulf of Mexico by the Mississippi River in the past 200 years.
• More than 15.9 million water wells serve the United States.
• Thirty-eight percent of the U.S. population depends on groundwater for its drinking water supply, from both public and private wells.
• Michigan, with an estimated 1.1 million households served by private water wells, has the largest such population of any state.
• 6 million Michigan citizens are served by private household wells.
• The amount of fresh groundwater in the Great Lakes Basin is approximately equal to the amount of water in Lake Huron.
• Direct and indirect discharges of groundwater to the Great Lakes are estimated to account for as much as 2.7% and 42% (respectively) of the inflows to the Great Lakes.
• In Michigan alone, there are more than 15,000 documented cases of groundwater contamination that could, potentially, affect the quality of water in the Great Lakes.
• Groundwater can become contaminated with a wide variety of chemicals and other substances including nutrients, salts, metals, petroleum hydrocarbons and fuel additives, chlorinated solvents and additives, radionuclides, pharmaceuticals and other emerging contaminants, pesticides, and microorganisms (including pathogens).
• Groundwater may improve the water quality of contaminated surface waters, providing areas of contaminant refuges in groundwater discharge zones in an otherwise contaminated surface water body.
• 45% of Michigan citizens are served by groundwater.
• Public water supplies using groundwater serve 1.7 million people in Michigan.
• Michigan has 9% of the nation’s public groundwater supply systems, the highest share of any state (12,038 out of 128,371).
• In 2017, Michigan used 2,888,325,875 gallons of groundwater.
• Daily groundwater withdrawals in Michigan total over 260 million gallons for irrigation as well as 64 million gallons from on-site wells for industrial purposes.

Sources:  National Groundwater Association, Great Lakes Executive Committee Annex 8 Subcommittee, Michigan Department of Environmental Quality.