Why are the Little Colorado River and Havasu Creek blue? In Grand Canyon there are two side streams that carry heavy carbonate loads and deposit travertine along their lengths. The Little Colorado and Havasu Creek both rise from springs a few miles above the river and are separated by over one hundred river miles.

The white carbonate precipitate in each makes the light turquoise color of the water strikingly visible. What mineral in the water gives it the light turquoise color?
The color of the water is determined by depth and mineral composition. Calcium carbonate is carried in the Little Colorado river water column and coats the river bottom. Calcium carbonate scatters white light (aka, looks white), so combined with water, which scatters blue light, a turquoise color is formed. When the water column is thin, white scattering of the calcium carbonate is more pronounced and the color of the water is lightened. In the deeper parts of the river, the color is a darker blue due to the smaller concentration of calcium carbonate (due to more volume of water) and the increased scattering of blue light through a thicker water column. 

This blog has a great explanation.