Why does Galveston's usually brown water randomly turn blue?

Not everyone is a fan of swimming in Galveston’s beach water. Many people, including recently a prominent sports media personality, think Galveston’s water is “dirty” because it often appears murky or brown. Still, it’s a common misconception that the color of water indicates how clean it is. “Any water, whether at the coast or inland, there can be water quality tests and sometimes water that’s very murky can be quite free of pollution, and other times, you can have clear water that has pollution,” said Hal Needham, an extreme weather and data scientist in Galveston. Galveston’s beach water isn’t just brown or murky, but can also appear slightly green, clear or even picturesque blue. Water in its purest state will be mostly clear with a pale blue tint, and water found in nature will never be colorless. Sediment, minerals and other organic material will cause water to have a shade of green or brown.