This 1896 illustration shows hydraulic mining being used by gold miners in the far West of the United States. Hydraulic mining is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment. The practice is an ancient one, but in modern times, it began to be used in the mid-1800s. Its environmental effect is very negative on lands that border rivers and streams. High-pressure water jets have also been used in the underground mining of coal, to break up the coal seam and wash the resulting coal slurry toward a collection point.