As expected, my visit last week to Malakoff Diggins State Historic Park evoked mixed emotions. The Diggins is a large (by historical standards) pit mine in the gold country northeast of Sacramento, where hydraulic mining was used to blast away whole hillsides in search of the gold. Large volumes of water were diverted and collected uphill and then piped down to the mine, where thanks to gravitational force the water could be sprayed at high pressure and volume through impressive cannon-like monitors to wash away the gold-bearing gravel sediments. The resulting gravel slurry then flowed through large sluices where the gold settled out, often with mercury added to aid the separation.
The removal of whole hillsides and the erosion that followed were undoubtedly an environmental disaster, at least locally. But the impact was felt far more widely. The large volumes of waste mine tailings were washed down into the local watersheds (in the case of Malakoff, this meant the Yuba River). Havoc ensued downstream in the rich Sacramento Valley farming region, where the sediment covered farmland, clogged waterways, and induced flooding. The farmers sued the mine, and in 1884 the Sawyer decision largely put an end to the practice.
Despite the mess, one can't help but admire the ingenuity and resourcefulness of human beings driven by greed. They got the job done. And the Diggins are beautiful in their fashion, having been compared, aptly, to a miniature, human-made Bryce Canyon.
But for me, the most heartening aspect of my visit was seeing nature take back the Diggins. The floor of the pit is covered over with pines and manzanita at the margins, thickets of willow in the flats, and a marsh of reeds and water plants at the lowest point. Within another century or so, I suspect the "canyon" walls will be obscured behind the trees, and visitors will wonder what all the fuss was about. The mercury contamination will, of course, be with us for a good while, as will the changes in the Yuba.
Color contrasts between the sediments are striking:
Here's a monitor, taking aim:
The Hiller tunnel allowed the tailings to wash from the basin into the Yuba watershed:
I wouldn't want to swim in murky Diggins Lake, but the vegetation seems satisfied with the accommodations:
Nature takes back the metal pipes, too:
Humans are helping out a little with the recovery. Here a "brush box" does its job of slowing the erosion process and trapping soils, allowing saplings to take root: