In the last inspection of the Hastings Mine in 1997, sediments in a drainage below the mine were found to contain ten parts per million of mercury; furthermore, spring water below the mine exhibited a water concentration of .31 micrograms per liter (a violation of the State of California standard for receiving waters of .05 micrograms per liter). Miles of underground shafts were driven in the course of working the quicksilver deposits in the area. In 1989, Earth Metrics reviewed old 1918 maps of workings of the Hastings and St. John's Mines and found that mine shafts were not driven into the site prior to the year 1918.
In the final examination of the Hastings Mine in 1997, sediments beneath the mine contained ten parts per million of mercury; additionally, spring water below the mine showed a concentration of .31 micrograms per liter (a breach of California's standard for receiving waters at .05 micrograms per liter). Miles of underground tunnels were excavated during the mining of quicksilver deposits in the area. In 1989, Earth Metrics reviewed old maps from 1918 detailing the workings of the Hastings and St. John's Mines and discovered that mine shafts were not constructed before 1918.