As a consequence of a year-long feasibility study, the Wisconsin Department of Natural Resources (WDNR) proposed on Dec. 21 that its Vessel General Permit be modified to harmonize it with international ballast water discharge rules. The requirements become effective in 2012 for new ocean-going vessels and in 2014 for existing ocean-going vessels. When not fully loaded, commercial cargo ships must take on water (ballast) to maintain their stability. Once pumped on board, ballast water is stored in narrow cavities (ballast tanks) built into the hull of a ship. Ballast water pumped onboard in one port may inadvertently contain aquatic organisms that are then released when ballast is discharged in another port.