The VA Lines are most commonly run between 2.9 and 3.1, but they can be run a little lower and certainly much higher if you have enough skill and knowledge of the river. The limiting factor is usually the Spout. There's a rock behind the curtain called the Big Toe that comes into play as the level drops below 3.0; one local shattered his elbow on it below 2.8. Above 3.2 the hole at the base of the Spout gets really violent, These days, most paddlers are running it on the right. At higher water, U-hole and S-turn merge into one big technical rapid and setting safety is a good idea. Virginia is runnable up to 4 feet but 95% of local paddlers' personal cut off is between 3.1 and 3.4
The gage is located at Little Falls (aka Brookmont) Dam, where the river is very wide. Consequently, an inch on the gage can translate to a foot at Great Falls. The gage is also 8-9 miles downstream, so if the river is rising or falling rapidly there could be a discrepancy between the gage reading and the actual level. Scout the rapids visually if there is any doubt. (You were going to do that anyway, right?)
|POTOMAC RIVER NEAR WASH, DC LITTLE FALLS PUMP STA|
|usgs-01646500||2.50 - 3.95 ft||V||00h26m||3.14 ft (running)|
|U-hole develops a pretty bad pocket hole. Normans is recommended instead. The Spout becomes a burly hole and the Crack is the sneak option above 3.3.|
Reports give the public a chance to report on river conditions throughout the country as well as log the history of a river.