A diagram is presented which shows the light scattering effectiveness of small particles when they are suspended in water. The effective scattering is plotted as a function of the radius of the particles (0.005 to 5 µ), of the wave length of the energy being scattered (0.35 to 0.8 µ), and of the relative refractive index of the material in the particle when compared to water (1.02 to 1.40). The diagram covers the range of variables for most fine materials which are found suspended in natural waters.