Water levels on the Great Lakes are already low ... and global warming could drive them even lower.
That's according to the National Wildlife Federation, which released a new report on the situation today.
The group says scientific studies show that climate change may worsen the low-water problem in the coming century. And it may intensify water shortages in dry areas such as the desert Southwest, which could try to get hold of Great Lakes water.
The federation says climate change is another reason for the Great Lakes states to ratify a proposed compact to protect the region's water.
The compact has drawn significant opposition in Ohio, where critics say it could hamper economic development and property rights.