Situational Awareness (Sunday, 2024-09-15)
Potomac River flows have been falling, but it looks like relief is on the way. According to the Middle Atlantic River Forecast Center, significant rainfall is expected over the next 3 days, with a predicted average accumulation in the Potomac basin above Little Fall of 1.3 inches. The week-long outlook calls for a total of approximately 2.4 inches.
Special Conditions
River flow fluctuations caused by September 12th bathymetric surveys by National Park Service contractors at Potomac Dam No. 4 are now affecting flows at the Little Falls gage.
Recent basin-wide average precipitation (above Little Falls):
(based on CO-OP's Low Flow Forecast System analysis of Middle Atlantic River Forecast Center (MARFC) gridded multisensor precipitation estimates)
Yesterday's area-weighted average basin precipitation: 0 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0 (inches)
Daily flows:
Little Falls gage flow 2024-09-14: 1086 MGD (1680 cfs)
Little Falls gage flow 2024-09-15: 885 MGD (est., based on recently available real-time data) (1370 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2024-09-14: 989 MGD (1530 cfs)
Point of Rocks flow 2024-09-15: 1047 MGD (est., based on recently available real-time data) (1620 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2024-09-14: 1137 MGD (1760 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 (2024-09-14):
Fairfax Water Corbalis withdrawal - Potomac: 119 MGD
WSSC Water Potomac withdrawal: 127 MGD
Washington Aqueduct withdrawal - Great Falls: 93 MGD
Washington Aqueduct withdrawal - Little Falls: 51 MGD
Loudoun Water withdrawal: 13 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 403 MGD
Total net Potomac withdrawal: 396 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1530 cfs
QPR, obs: 1530 cfs
QPR, WS: 0 cfs
Interstate Commission on the Potomac River Basin