These industries employed an estimated 939 people. Most of the businesses in Humboldt County purchase their water from a PWS or obtain water from a private supply not requiring a permit. There is one water use permit for industry in Humboldt County. Currently there are two water use permits issued for power production in the county, with no withdrawal reported in 1990. Mining Water Use Mining in Humboldt County consists of sand and gravel extraction.
Activity varies from year to year based upon construction needs.
Seven water permits were issued for mining in the county. The Iowa State-Wide Rural Well Water Survey, 1990. The UHL's test results for the county show that the average year 17.0 percent of wells tested for nitrates exceeded the recommended maximum. These test results are based on non-random samples. The University of Iowa Hygienic Laboratory, Private Well Water Quality, 1990-1994.