Cistern Spring and Steamboat Geyser are linked underground. During a major eruption of Steamboat, the water in Cistern Spring's pool drains. Normally, Cistern is a beautiful blue pool from which water continually overflows. It is quite creative, depositing as much as 1/2 inch (12mm) of grayish sinter each year. By comparison, Old Faithful Geyser and many other thermal features may build at the rate of only 1/2 to 1 inch (12 - 25mm) per century. Cistern Spring's influence expands throughout the lodgepole pine forest below. This forest has been slowly flooded with silica rich water since 1965. The pioneering lodgepole pine forest at Norris is in constant flux, retreating here and in other areas of increasing heat while advancing in places of diminished thermal activity.