Groundwater’s importance to the environment
Hydrologists estimate U.S. groundwater reserves to be at least 33,000 trillion gallons — equal to the amount discharged into the Gulf of Mexico by the Mississippi River in the past 200 years.
About a quarter of all U.S. rainfall becomes groundwater. Groundwater provides much of the flow of many streams; many lakes and streams are “windows” to the water table.
20 to 30 times
At any given moment, groundwater is 20 to 30 times greater than the amount in all the lakes, streams, and rivers of the United States.