Situational Awareness (Friday, 2026-08-07)
Potomac River flow at the Point of Rocks gage has climbed slightly above 2000 cfs, CO-OP’s threshold for daily drought monitoring. The Mid-Atlantic River Forecast Center (MARFC) predicts there is a greater than 50% probability that flows remain above this level over the next 10 days. If it becomes clearer that higher flows will be sustained for a reasonable amount of time, daily drought monitoring will be discontinued. MARFC predicts 0.3 to 0.4 inches of accumulated precipitation above Point of Rocks over the next 3 days. The 10-day outlook expects a total of approximately one inch of rain in the basin.
Special Conditions
The National Park Service has informed us that the annual off-water inspection at Potomac Dam No. 4 in Washington County, MD, will take next week (Tuesday, August 11, 2026). During this time, the hydroelectric operator – Eagle Creek Renewables will be diverting water off of the run-of-river dam crest through their powerhouse turbines. This will cause intra-daily flow fluctuations at the Point of Rocks gage.
Daily flows:
Little Falls gage flow 2026-08-06: 1590 MGD (2460 cfs)
Little Falls gage flow 2026-08-07: 1616 MGD (est., based on recently available real-time data) (2500 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-08-06: 1176 MGD (1820 cfs)
Point of Rocks flow 2026-08-07: 1338 MGD (est., based on recently available real-time data) (2070 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-08-06: 1590 MGD (2460 cfs)
Note: Estimated flow below Great Falls intake is flow at Little Falls plus Little Falls water supply withdrawal.
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2026-08-06):
Fairfax Water Corbalis withdrawal - Potomac: 103 MGD
WSSC Water Potomac withdrawal: 153 MGD
Washington Aqueduct withdrawal - Great Falls: 114 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 382 MGD
Total net Potomac withdrawal: 376 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1820 cfs
QPR, obs: 1820 cfs
QPR, WS: 0 cfs
Interstate Commission on the Potomac River Basin