Groundwater
Groundwater is water beneath the earth’s surface that fills in open spaces (or pores) in soil or rock, similar to the way water fills a sponge. Contrary to popular belief, groundwater is typically not found as underground rivers or lakes. Groundwater is commonly found in geologic, water-bearing formations called aquifers. Groundwater comes from rain or snow that falls to the earth and infiltrates through the ground. Water seeping down below the ground’s surface adds to the water already there and is said to be recharging (replenishing) the groundwater. The amount of rain or snow that falls in an area—and the rate at which it falls—can influence groundwater levels.

Surface Water
Surface water is water in lakes, streams, rivers and oceans—water that is found on the earth’s surface. Groundwater and surface water are often interconnected. Groundwater can move through the ground and into a lake or river. Or, water in a lake can seep down into the ground and become groundwater. In the image below, notice how the surface of the river is at the same level as the water table.