Kids splash each other at the Tenino Quarry Pool during a warm afternoon last month.
The mystery of what is at the bottom of the Tenino Quarry Pool may be solved on Thursday when divers explore the depths of the swimming hole and teams utilize sonar technology to map the pool.
The event will begin at noon on Thursday at the Quarry Pool.
The event is being sponsored by Olympia Underwater Sports, Don Juan’s Mexican Kitchen and the city of Tenino. All photos and video from the dive are being offered exclusively to King 5 Evening Magazine.
Mayor Wayne Fournier said learning what is at the bottom of the pool could be an asset to the city. If the underwater environment is interesting it could be utilized as a dive park, he said, or if there is a piece of old mining equipment from the turn of the last century, it could be recovered and put on display.
The pool is at the location of a sandstone quarry that was established in the 1890s. The quarry shut down in the 1920s when it is believed workers hit a natural spring, causing the quarry to rapidly fill with water.
Fournier said the creation of the pool could also have been caused when workers walked off the job after a labor dispute. When they left, they turned off the pumps, and the quarry could have been filled with water then. Regardless, the pool is known to be spring-fed because of the freshwater circulating to the top, he said.
This is the first exploration of this kind in the pool, and the city expects to gain some valuable information from it. In the past, primitive methods of judging depth using weights tied to ropes have been used to determine the pool is more than 100 feet deep.
Although some answers will be found, Fournier said the pool will always have questions surrounding it.
“I hope the mystery never goes away,” he said.
