Droughts can affect groundwater levels and freshwater springs..
Comparison of water from an underground spring in Georgia during non-drought and drought periods.
Radium Springs, Albany, Georgia, USA
Freshwater springs on the land's surface are fed by groudwater findings its way to the surface. But, groundwater levels go up and down depending on the supply of water from precipitation and flow through the ground. During a drought, groundwater levels can fall, which affects the water coming to the surface in the spring.
As this picture shows, during non-drought periods clear freshwater flows to the land surface, as the left side picture shows. The right side picture was taken when a drought affected Georgia. Groundwater levels fell to a level that no longer "fed" the spring, resulting in a stagnant pond.
Image Dimensions: 1200 x 380
Location Taken: Albany, GA, US