The marks on the water are caused by a very rare occurrence called rainfall. Here is a short explanation for those of you who don't understand the concept of rain.

Rain is liquid precipitation: water falling from the sky. Raindrops fall to Earth when clouds become saturated, or filled, with water droplets. Millions of water droplets bump into each other as they gather in a cloud. When a small water droplet bumps into a bigger one, it condenses, or combines, with the larger one. As this continues to happen, the droplet gets heavier and heavier. When the water droplet becomes too heavy to continue floating around in the cloud, it falls to the ground.

In this case it lasted for about 10 minutes and the phenomenon has not been seen since.