The industries employed an estimated 29,929 people. Most of the businesses in Polk County purchase their water from a PWS or obtain their water from a private supply not requiring a permit. There are 13 water use permits for industry in Polk County. Currently there is one water use permit issued for power production in the county, which consumes a limited amount of water per year. Mining Water Use Mining in Polk County consists of sand and gravel extraction.
Activity varies from year to year based upon construction needs.
Six 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 also show that in an average year 6.0 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.