Wanting 12 feet

In theory, the Ohio River has a navigation channel that is guaranteed to be nine feet deep. In practice, the channel is at least 12 feet. Otherwise coal barges loaded to 10 feet deep would not be able to use the river when it's at normal pool.

Those extra three feet allow boats to push more cargo than they otherwise would. Now some businesspeople in Oklahoma would like a 12-foot channel on their river, too. Check out this story to see what an extra three feet could mean there.