The Center lines are the only part of the main falls that can't be run at summer low water. As of 2018, Minimum for Grace was nearly 3.5. The rapid next door carries more of the flow now. Above 3.8 the landing off Grace gets rowdier and there's very little time to recover if something goes wrong.
The gauge 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||3.30 - 3.95 ft||V+||00h47m||3.95 ft (too high)|
|stout level for Grace, and the Fingers are fluffy. Flatliner (Ring finger) can be boofed at these levels.|
Reports give the public a chance to report on river conditions throughout the country as well as log the history of a river.
|Potomac [MD]||Middle Finger||3.7||Potomac Pathways|
|Potomac River [MD]||Two kayakers running the Falls||n/a||Scott Anderson|
|4y203d02h03m||@Potomac 3. Great Falls (Center Lines) [VA]||The Thumb||3.36 ft||Matt Jackson|
|8y49d09h17m||/Potomac River-Great Falls (Center Lines)||Great Falls||0 cfs||Ben Selleck|
|9y249d21h35m||/Potomac River-Great Falls (Center Lines) [MD]||Grace Under Pressure||0 cfs||Brett Mayer|
|9y249d21h36m||/Potomac River-Great Falls (Center Lines) [MD]||Grace Under Pressure||0 cfs||Brett Mayer|
|> 10 years||@Potomac River Great Falls (Center Lines) [MD]||Account of 02/11/10||n/a||n/a|
|> 10 years||Great Falls [VA]||http://www.lovelylightstudio.com/||n/a||150737|