Here's my annual warning to respect the Potomac. People die in this stretch of river every year.
Fletcher's stops renting if the water is expected to go over 5ft. I'm sure someone will give more accurate rules for when fletcher's stops renting boats.
When fishing from shore, just remember to not fall in. As the water gets higher, it gets muddier. Also, when the water goes up to the 10ft level large trees may be flowing down the river.
Take advantage of good water levels when you have them. Plan to take a morning off of work to enjoy the river when the weather and water levels are nice. Sometimes we can lose weeks to high water levels.
Carl