The Providence Mine Brownfield site is a 45-acre property owned by the City of Nevada City located at the end of Providence Mine Road along the south side of Deer Creek, approximately one mile downstream of downtown Nevada City. The Providence Mine was a large hard rock gold mine which operated from 1851 to 1919 and produced an estimated $20 million in gold and associated minerals. The operation included a 40-stamp mill and a chlorination works where releases of mercury and concentrated heavy metals likely occurred. The City-owned property includes the eastern portion of the former mine site. A popular-use trail traverses the site, passing directly through the mine features in the northern portion of the site.

The Providence Mine Brownfields Cleanup Project will be performed on two areas in the northwestern portion of the property. The "Mine Features Area" is located on a benched area above Deer Creek and adjacent to the east of Providence Mine Road where several mine structures and the Providence Mine Shaft were located. The "Waste Rock Area" is located on a steep slope extending from the Mine Features area to Deer Creek.

Cleanup work proposed for the Mine Features Area includes excavation and off-site disposal of a limited amount of highly contaminated soil, trail construction, capping with clean soil and phytoremediation (the use of plants to extract contaminants from near-surface soil).

Cleanup work proposed for the Waste Rock Area includes slope benching and re-grading to lower mine waste slope angles below the current angle of repose, soil stabilization using physical methods, stream bank restoration using rock walls or rock armoring, and phytoremediation to extract contaminants, stabilize soil, and create access deterrents.

The Stiles Mill site is a 2.14-acre city-owned property located across Deer Creek from downtown Nevada City just upstream of the Pine Street Bridge at the confluence of Gold Run and Deer Creek. The site was operated in the mid to late 1800s as a wood planning mill and a custom quartz stamp mill which crushed ore from many small local mines. The mill has been completely removed and no visible tailings remain; however, a partially collapsed shaft and waste pile and a stockpile of mine waste with relatively high levels of lead and arsenic remain on the site along the banks of Deer Creek. Brownfields Cleanup work proposed for the Stiles Mill site includes re-grading of mine waste piles and capping with clean soil, stream band restoration to stop erosion of mine waste into Deer Creek and cleanup of a trail leading from the corner of Sacramento and Clark Streets onto the site. A phytoremediation pilot study may also be performed to test the use of plants to extract contaminants from near-surface soil.