The main man-made releases of zinc to the environment and water are from metal production processes, from industrial combustion of coal, from waste incineration and from worn rubber tyres on vehicles. Small amounts are also released to the ground water from the earth's crust.
In addition to the recommended above mentioned answers, I would like to point out the importance of zinc to public health;
Zinc is an essential trace element found in virtually all food and potable water in the form of salts or organic complexes. The diet is normally the principal source of zinc. Regards