Many people confuse springs with groundwater. Most folks assume that if they dig and see water they've hit a spring. More often than not, they've dug into the water table. If the water runs into a hole quickly thru a sandy layer or lense, the greater the impression of having hit a spring. People often dig into clay and assume that the water table is deep because they don't see water running into the hole. Often the water is there but it takes a long time to flow into the hole due to the slow permeability of the clay. Under these conditions, it can take days (or weeks) for the water viewed in a hole to reach equilibrium with the surrounding "spring" or water table.

Springs, specifically contact springs, are the result of a water bearing soil layer overriding an impermeable (or nearly so) layer of densely packed loamy thru clayey material or bedrock. Other springs are formed where a fracture in water bearing fractured rock comes to or close to the surface at an elevation below the top of the water held in the rock. The easiest way to differentiate between a spring and groundwater is that a spring is under head and generally overlies an unsaturated layer. Where the edge of the slowly permeable layer comes near the surface, as on a slope, that is where you see the contact spring seep.

Whether a spring or perched groundwater, if you excavate thru the layer that perches the water or that the spring is flowing on top of, you may create a drain. That is where a good set of borings that stop above a clay or rock layer as well as some that penetrate is helpful to see what is really going on. If the level of water is higher in holes above the clay/rock than in those that penetrate it, chances are that you will create a drain if you penetrate or remove the clay/rock layer. You could realistically expect a spring to fill a pond up to the level that it stands in the borehole provided that everything below and the dam is sealed sufficiently and the flow rate of the spring offsets the evaporation and leakage loss. Apply more water (head) than you see in the borehole, and the spring will reverse and seek a lower point elsewhere to surface. Just to complicate things a little more, some soils can have a contact spring or perched groundwater that overlies the true (apparent) water table separated by a few inches or many feet.

Hope this makes some sense. Sometimes it is very difficult to really understand the hydrology of a site. All you really have to remember is that water flows from high head to low head and the rest sometimes falls into place or begins to make sense.