Think of this the next time you kayak, drive over, run by or, simply, stare at the Potomac River: Its ruin would cost the D.C. region nearly $15 billion in the first month, according to a report ...

Upstream, the Potomac River is rising rapidly. At Point of Rocks, the river hit 21.5 feet by 4:45 a.m. Thursday and is projected to crest at 23.6 feet, rivaling water levels not seen since 1910.