This dataset includes data for in-situ solid materials and suspended sediments from surface-water samples, as well as surface-water chemistry from samples collected during storm events at Malakoff Diggins State Historic Park, Nevada County, California. In-situ solid samples were collected during 2015 along six vertical transects along the cliff walls of the mine pit. Surface-water samples were collected during 2014 and 2016 from Hiller Tunnel and from drainage networks below the in-situ sampling sites during runoff conditions. In-situ and suspended-sediment samples were analyzed for grain-size distribution, X-ray diffraction (XRD) for quantitative mineralogy, inductively coupled plasma – mass spectrometry (ICP-MS) for trace elements, and inductively coupled plasma – optical emission spectroscopy (ICP-OES) for major elements. Water samples (both filtered and non-filtered) were analyzed for trace elements including aluminum, arsenic, barium, beryllium, cadmium, chromium, copper, iron, lead, mercury, nickel, zinc, and total suspended sediment. Water-quality field measurements included water temperature, specific conductance, dissolved oxygen, pH, and oxidation-reduction potential. There are four files (*.csv) in this dataset: 1) data dictionary; 2) sediment data; 3) water data; and 4) quality assurance data.