The color you see is a result of the park controlling the algae growth.
Since the rivers and streams at the park are mostly artificial, the water would remain stagnant and cause algae to grow and choke out the ecosystems in the water. In areas where there is more sunlight, the chemical's color reduces the UV rays penetration in the water.
Most of Busch Gardens water is moving via fountains, pumps, and streams.. but the larger areas were there is standing stagnant water or areas were there is sun hitting large areas of water, a non harmful eco-friendly chemical (probably a natural bacteria) is used to control the health of the environment.
This also reduces the mosquito larvae as standing- stagnant water is a breading ground for one of Virginia's most annoying pests.
I am not sure of the actual products used- however, the park's stand on the environment and their dedication to being environmentally responsible is outstanding.