Which type of non-storm water discharge is typically not permitted under municipal NPDES storm water discharge permits?

The correct answer pertains to the type of discharge that typically is not allowed under municipal NPDES storm water discharge permits, which is automobile detailing. This activity is often classified as a non-storm water discharge due to the potential for pollutants such as soaps, oils, and other cleaning agents to enter storm drains, which can lead to contamination of local water bodies.

Municipal NPDES permits are designed to manage discharges of storm water and minimize pollution. Activities like automobile detailing generate runoff that can carry harmful substances, making them particularly problematic. Other options, although they may involve water use, can sometimes be conducted in ways that mitigate their environmental impact or may have specific allowances provided under permits.