The unusual colors is the result of lower temperatures which have allowed yellow bacteria and algae to grow on the lining of the pool. The clear water of the pool reflects the blues but absorbs the other hues of the color spectrum. The combination of blue and yellow then produces green. Objects thrown into the pool and natural debris have caused a further decrease in temperature, resulting in a change of bacteria and algae growth and thus a change of color. The edge of the pool is now orange and brown. If the temperature continues to decrease, the pool may lose its emerald color.