A lot of old quarries are filled with water but some are returned to agriculture, root crops can't be grown for five years though until the soil structure has regained most of it's original body so grass and cereals only, the water is usually very clear because it's mainly ground water instead of being stream fed, if the quarries are to be filled with water they are clay lined using the clay from the bottom of the "dig" after the usable minerals have been extracted
Rog