The color of water is one of the best reflections of the health of the surrounding environment. Blue glacial ice is often thought of as the purest form of water. A mountain stream is usually clean and clear without color at its headwaters, but soon starts to pick up colors and contaminants as it runs down through the landscape of our modern world. Pollution and some of the by-products of poorly planned development can then spread all sorts of artificial casts in the water. This slide show from the book Our Beautiful, Fragile World depicts water at its purest–and its most polluted.