Stales,
Agua Azul is a river that runs through the mountainous jungle near the southern border of Mexico and Guatemala. During the rainy season, the water is greenish, but during the dry times it is a most wonderous color blue. I believe it originates in the limestone beds of the Yucat�n. [so sue me if I'm wrong-e] I know that there are some other rivers in that general area that are dangerous to swim in because of chemicals in the water that are toxic to humans. But not here.

http://www.thresholds.net/aguazul/aguazul.htm

post edit Yes! The color of your Blue Lake is the color of Agua Azul when at it's finest!