The industries employed an estimated 23,794 people. Most of the businesses in Linn 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 Linn County. Currently there are four water use permits issued for power production in the county, which withdraws about 52,213 million gallons per year. Mining Water Use Mining in Linn County consists of sand and gravel extraction.
Activity varies from year to year based upon construction needs.
Sixteen water permits were issued for mining in the county. The State-Wide Rural Well Water Survey completed in 1989 indicates the following quality results for private well water, shown in Table 3, for the east hydrogeologic region in which Linn County is located. The Iowa State-Wide Rural Well Water Survey, 1990. The UHL's test results for the county also show that in an average year 10.5 percent of wells tested for nitrates exceeded the recommended maximum. These test results are based on non-random samples.