Sawmill is the largest member of the Sawmill Complex. It is a fountain-type geyser, its bursting eruptions playing through a funnel shaped pool. Typical intervals are one to three hours. Durations can range from 9 minutes to more than 4 hours with most in the 30 to 50 minute range. Heights can exceed 35 feet. When the complex is in the Sawmill Mode, Sawmill Geyser is usually in eruption about one third of the time.
Sawmill was named for the whirring noise it makes during its eruption and/or for the rotary motion in its pool during the eruption. Either way, Sawmill is an enjoyable geyser. It is fun to watch and to hear.
At the opening of the Park for 2017, Sawmill and its group were observed by many people to be in an unexpected, widespread "pause" or "hold" affecting most of the geysers there. Many geysers had orange bacteria, indicative of a lack of recent hot water, growing in their runoff channels, or even in the vents themselves. Sawmill has not been seen yet this year as of this writing (4/23/17). The significance of this "pause" is unclear; keep an eye open, not just on the geysers but on relevant social-media sites (e.g. the Geyser Gazers group on Facebook) for developing information.
|After an eruption, Sawmill drains, leading many first-time visitors who see the empty crater, to believe that the geyser is dead.
Prior to an eruption, Sawmill, along with the other features in the complex, begins to slowly fill. At this time, Tardy and Spasmodic often start to erupt. preceding Sawmill. As the water rises, a battle often takes place between Penta and Sawmill. Whichever erupts first dooms the other, causing the other to drain without erupting.
Just prior to the eruption, Sawmill will be near or just at overflow. At this time, bubbles start rising in the pool. At first the bubble collapse before they reach the surface but eventually they reach the surface, at which point the eruption is usually near.
After an eruption of Sawmill drains and all of the other features in the complex drop from a few inches to many feet. In general, the longer the eruption the deeper the drain. A long eruption of Sawmill causes a "deep drain" which often accompanies rare behavior in some of the other members of the complex.