ICG Hazard, LLC, operates the under Ridge surface coal mine in Leslie County, Kentucky, under a National Pollutant Discharge Elimination System permit issued by the Kentucky Division of Water (KDOW). As part of the operation, ICG discharges selenium into the surrounding water. Selenium is a naturally occurring element that endangers aquatic life once it reaches a certain concentration. KDOW knew when it issued the permit that mines in the area could produce selenium but did not specify discharge limits for the element in ICG's permit. Instead, the agency imposed a one-time monitoring requirement, which ICG met. Does ICG's discharge of selenium violate the Clean Water Act? Explain.