sentences:  By the early 1870s water diversions were being used to irrigate an extensive area of corn and other crops.In the mid-1870s a small water-powered, silver-lead furnace, "Agua Fria Furnace," was built to work the ores from what would become the Iron King mine area.The small plant, built at the site of Woolsey's earlier mill at today's Humboldt, proved the value of the region, but was too isolated to make a profit.