For roughly a hundred years, the Swan River didn't flow through its valley — it flowed under it. Bucket-line dredges, including the Bucyrus dredge, turned the valley upside down between the 1890s and early 1900s, leaving the river running invisibly beneath miles of cobble tailings along Tiger Road.

Beginning in 2016, Summit County and its partners excavated the tailings, recovered buried topsoil, and rebuilt the channel. Reach A opened in 2017, converting a half-mile flooded ditch into a mile of meandering stream; Reach B followed in 2020, with later reaches continuing upstream. Aquatic insects, native fish and trout, and stream-dependent birds like the American dipper have returned to the restored water. Raw dredge-rock piles still flank the corridor, so you can read the before-and-after in a single view.

Walk in from pullouts along Tiger Road, about 3 miles east of CO-9 between Breckenridge and Keystone; the valley also links to the county recpath system toward town. Respect any active-construction closures as later reaches proceed.