As can be seen in the index map below (from Pardee's USGS Bulletin) , the Pioneer District overlaps Powell and Granite Counties.
We've recently had occasion to gather together some information on the three bucket-line gold dredges that are known to have operated in the district, near the town of Pioneer. An excellent source of information on the dredges and other district history is the thesis Jeff Loen wrote on the district in 1986.
The first is said by Pardee to have operated in 1905 and 1906, and to have achieved only poor recovery. This dredge is likely the "Stewart" which is shown in this picture in the UM photo library. The scan lacks good resolution but the copy in the library clearly shows the word "Stewart" at the top of the dredge. Very likely this dredge was constructed and operated by the Gold Creek-Montana Co., Ltd. We can't find any person named "Stewart" connected to Pioneer though of course the name "Stuart" is intimately associated with the district's history. Perhaps, as at Philipsburg, the name was mis-spelled.
The second dredge was a large Yuba named the "Mosier" that operated from 1933 to 1941 (according to Pardee) and is responsible for most of the dredging at Pioneer. The Mosier burned in the late 1960's and the bull gear and other equipment have been visible in a pond below Pioneer. The Mosier dredge had a wooden hull and several pictures of its construction are archived in the photo collection of the University of Montana library. Below is an image of the Mosier from the Pardee report.
The third dredge was a small Yuba that operated in Reservoir Gulch just west of Pioneer in the mid-1950s. Jeff Loen reports that the years of operation were 1955-1957, and that the operator was the Montana Gold and Chemical Co. of Seattle. Placer miner Jim White reports that he worked with the welder for that dredge, Marion Clemens, and learned the history of the dredge from him. The Dredge Master was Buck Lightfoot. This dredge is still in place and largely intact. It has a steel hull, and we refer to it informally as the "Iron Dredge". Pix to follow.