It doesn't take much. I live near the Potomac, just upstream of Great Falls and DC. People drown on the flat stretches every summer. Usually a family picnic,

It doesn't take much. I live near the Potomac, just upstream of Great Falls and DC. People drown on the flat stretches every summer. Usually a family picnic, somebody goes for a quick dip, and never returns. It looks calm. It isn't. And just downstream, world class kayakers paddle Great Falls for fun and practice. It's wild (and sad) to think about the two groups of river users.