Willoughby: The on-again off-again Hunter Creek Mill

Tim Willoughby
Legends & Legacies

Hunter Creek Mill near the entrance to the Cowenhoven Tunnel 1925. Aspen Historical Society photo

The hunter Creek Mill, around for around 40 years, opened and closed a number of times. Explaining its on-again off- again history provides context for explaining mining after 1900.

The mill was built in 1902 to process ores from the two-mile long Cowenhoven Tunnel that was driven to drain water from several Smuggler Mountain mines and to provide a cheaper way of getting the ore out of the mountain. Before that time much of the ore was not milled. Ore was sorted at the surface with the better ore shipped directly to the smelter and the lesser quality ore dumped on site. But the quantity of the better ore was dropping and milling processes improved to make the dump material more profitable. In addition, the Hunter Creek Mill could process ore from smaller mines (the larger ones often had their own mills), and mines with lower grade ore.

The mill opened with the capability of profitably milling ore with as little as nine ounces of silver ore per ton and with only 4% lead. The new milling process required lots of water and to be profitable it needed to be on the railroad loop, both provided by its location. The process used two major milling innovations. One was Huntington mills, essentially a series of screens with tiny holes where ground-up ore was forced, using water, through leaving a fine powder. The powder was then fed into Frue vanners, a device that had been used in Australia in the 1860s but improved and patented by William Frue in the 1870s. Again, using water sprayed on a revolving cloth bed the powder was introduced and the lighter non-mineral material washed away leaving the heavier mineral. The mill could handle over a hundred tons of ore a day with an 87.5% mineral recovery.

In the next few years it took on ore from the Bushwacker, Enterprise, Marple, Aspen, Montezuma, Della S., Little Annie and Mineral Farm mines. Much of the material came from their mines dumps. As an example, the Aspen Mine dump had 30,000 tons to process. The Marple, located up Queens gulch, had ore from its tunnel and hauled it to the mill using 35 jacks. 50 tons came from the Little Annie dumps.

The mill would process shipments from a mine and when they stopped coming it would close down until another mine shipped ore. When they were really busy they had two shifts, but most of the time only one. When they closed for a few days they would let the community know because that meant fishing would be better, as there would not be left over dump material in the Roaring Fork. You might not want the fish anyway because unprocessed sewer water emptied into the river just upstream.

Mill equipment breaks down often so that would shut the operation down too. Workers were excited after being off work for a while when Wells Fargo notified the town a 1,000 pound casting of a mill part had arrived.

The mill, it appears, shut down in 1910 and then reopened in 1916 to process the Cowenhoven dumps estimated 100,000 tons. The Cowenhoven operation was making 50-cents a ton from that operation ($10 a ton in today’s dollars).

The mill closed again in 1920 then reopened in 1921 when the Park Tunnel began operation. Then in 1922 smelters changed their rates and it was the same rate for unmilled Aspen ore as it had been from the Hunter Creek Mill processed ore so mines shipped direct and the mill closed. It reopened briefly in 1923. In 1925 the mill system was remodeled to increase capacity to 300 tons/day, closed again then reopened in 1926 after converting to a whole new process, a flotation process (the same as used today). It closed again and did not reopen again until 1937 when a new company, Metals Recovery, bought the mill and added a 500-ton ball crusher. It operated only in the summer months partially because while the Montezuma Mine, a major customer, above Ashcroft ran all year it didn’t ship its ore to town in the winter.

My uncle John Herron and his brother Bill leased the mill in 1940 to process ore from the Henry Clay dump, that had an estimated half million tons of dump material they thought would yield anywhere from 3 to 28 ounces of silver a ton.

The Hunter Creek Mill closed again and was put up for sale in 1942. The Herron brothers built their own mill nearby to process lead and zinc during the war years.

One of the greatest significances of the Hunter Creek mill is that it reduced the number of acres of Aspen’s mine dumps that at one time towered over the town.

Tim Willoughby’s family story parallels Aspen’s. He began sharing folklore while teaching at Aspen Country Day School and Colorado Mountain College. Now a tourist in his native town, he views it with historical perspective. Reach him at