The Blue River valley once contained beaver ponds, wet meadows, shrub thickets, and open grasslands shaped by fires set by Native Americans, which supported mountain bison, encouraged grasses and wildflowers, reduced tree cover, eased Ute travel, and provided willow shoots for basketmaking. Archeological evidence from Vail Pass shows Paleo-Indians were present at least 6,800 years ago, and bands of Utes, their descendants, lived and hunted in the valley. In 1839, Thomas J. Farnham described the upper Blue River valley as covered with buffalo and wild flowering glens. The pre-mining landscape included beaver lodges in shallow ponds, willow and alder thickets along wetlands, bunchgrass meadows with wildflowers on drier ground, lodgepole pines on the slopes, and spruce and fir at timberline and along wet drainages. In the 1800s, mining drastically altered this landscape as forests were cut, fires spread, and dredges turned valley floors into cobble piles. Gold-bearing minerals had been deposited in fractured ancient mountain rocks between 30 and 75 mya, and erosion carried heavier materials into nearby valley floors, where placer gold settled deep in stream channels between Breckenridge and the site of Dillon Reservoir. After gold was discovered in 1859, timber cutting for buildings, mine works, railroad ties, pipes, and dredge fuel denuded surrounding hillsides, and over more than eighty years miners used increasingly destructive methods to reach placer gold and mother lodes. Dredging, the most destructive method, operated in Summit County from 1898 to 1942, with nine dredge boats processing cobble deposits down to bedrock, consuming meadows and wetlands, and leaving barren cobble heaps across much of the valley floor. By 1942, vegetation and much of the soil needed for plant growth had been washed away, and in some places the Blue River disappeared underground. In 1988, Breckenridge began restoring the Blue River by moving cobble from the channel, relocating soil and native plants from development sites, purchasing eleven acres of leveled dredge tailings for the Riverwalk, reconfiguring 90,000 tons of cobble, and placing a plastic liner beneath the new channel. More than one quarter of the area was set aside for ecological restoration, using studied remnant plant communities as targets, salvaging 11,000 tons of living soil, transplanting more than 20,000 mature native plants, and collecting native seeds. The work continues with careful aftercare intended to protect the recovering ecosystem from weeds and restore the beauty and function of the Blue River Valley.