A dredge is a piece of mining equipment used on watercourses. It scoops or pumps/vacuums the bottom of the watercourse and pushes it onto the wash plant.
Floating industrial dredges had been used in the Klondike for a long time, since 1901. Prior to Tony's attempt, no industrial floating dredge had been used in the Klondike for a quarter century. They were in great use for a half century before that. 14,500 cu-yd of paydirt could be processed per day by a big dredge, scooped by bucket line, washed in an internal wash plant, caught in an internal sluice box system, with tailings dumped out the back on a conveyor. About a century ago, it was profitable to run dredges, but then it became less so, so dredges died out. In the 80s, it became profitable again, but by the 90s the price of gold had fallen, so the dredges again died out. A large dredge could process as much dirt in a minute as a mining crew of three could in a day. Most of the dredges were barges built on top of pontoons. The pond the dredge floats in extends the mining season, as anything underwater would be by definition thawed, so scooping paydirt from underwater results in scooping thawed pay, even when the pond is iced over, until it gets frozen deep, it could be workable. Like monitors, the pond's water thaws the ground. The dredges are held in place by spuds that're driven into the bed of the pond, and act as a pivot point around which the dredge rotates, to let the dredge scoop out in an arc. As of the start of season 5, there are no industrial gold dredges in operation in North America.
A small vacuum dredge used for hobby gold miners is obtained by Dustin Hurt after Melody discovers cracks in the bedrock of the glory hole that can't be mined out with the excavator, to vacuum out the gold deposits in them.
A 75-year old floating industrial dredge is bought by Tony Beets for season 5 in the Klondike. Prior to his $1million purchase, the dredge had not run for 30 years. Tony intends to have the dredge up and running for end of season 5 or season 6. The dredge, on Clear Creek is to be disassembled and moved to Eureka Creek. When it becomes operational, it will be the only functioning industrial gold dredge in North America.
A 7 decade old floating industrial bucket dredge is bought by Tony Beets midway into season 6 in the Klondike. The dredge, on Thistle Creek ran only 5 years in the 1940s, and at the time it was bought, was missing 1/3 of the buckets in the bucket chain.