The potential conflict is clear: The Great Lakes form the world's largest body of fresh water; the Southwest is growing more populous and thirsty. Thus, the Great Lakes Compact, an agreement to protect this increasingly valuable resource from being diverted to drier areas.But the agreement, reached in 2005 after negotiations among representatives of the eight U.S. states and two Canadian provinces bordering the lakes, is being blocked because of the objections of one Ohio legislator. The compact must be ratified by the legislatures of each state and province and by Congress.The Ohio House approved the compact twice. But a Senate vote has been held up by Sen. Timothy J. Grendell, R-Chesterland, who says that language in the compact would imperil Ohioans' right to control ponds, wells and streams on their properties.The compact simply bans diversions of the lakes' water outside their natural drainage area, with limited exceptions. It also sets rules for how communities inside the watershed use lake water and return it to its source. The compact is a thoroughly considered measure to protect one of Ohio's greatest resources.The Senate should pass the compact and let the agreement move forward.