Situational Awareness (Tuesday, 2025-11-18)
According to the Middle Atlantic River Forecast Center, no appreciable rainfall fell in the basin over the past 24 hours. Over the next 3 days, the average basin rainfall is expected to be between 0.25 and 0.75 inches.
Special Conditions
None
Daily flows:
Little Falls gage flow 2025-11-17: 963 MGD (1490 cfs)
Little Falls gage flow 2025-11-18: 957 MGD (est., based on recently available real-time data) (1480 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-11-17: 1047 MGD (1620 cfs)
Point of Rocks flow 2025-11-18: 1086 MGD (est., based on recently available real-time data) (1680 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-11-17: 963 MGD (1490 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 (2025-11-17):
Fairfax Water Corbalis withdrawal - Potomac: 85 MGD
WSSC Water Potomac withdrawal: 148 MGD
Washington Aqueduct withdrawal - Great Falls: 120 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 10 MGD
Loudoun Water Broad Run discharge: 8 MGD
Total Potomac withdrawal: 363 MGD
Total net Potomac withdrawal: 355 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1620 cfs
QPR, obs: 1620 cfs
QPR, WS: 0 cfs
Note to Loudoun Water: See NWS ensemble flow forecasts (HEFS, GEFS, NAEFS) for Point of Rocks flow for the next 7 days – https://www.weather.gov/erh/mmefs_marfc?id=PORM2&model=NAEFS. See US Army Corps of Engineers Potomac River Basin page for observed releases from Savage and Jennings Randolph reservoirs - https://water.usace.army.mil/office/nab/; See US Army Corps of Engineers North Branch Potomac River and Savage River page for scheduled releases - https://water.usace.army.mil/office/nab/releases/north-branch.
Note: Potomac River flow at Point of Rocks has dropped below the low-flow threshold of 2,000 cfs. When this occurs, per the Water Supply Coordination Agreement of 1982, CO-OP begins daily monitoring and reporting of Potomac flows and withdrawals on behalf of the CO-OP suppliers, Fairfax Water, Washington Aqueduct, and WSSC Water. Suppliers can review data at CO-OP's Data Portal at www.icprbcoop.org. Reports formatted in approved templates should be submitted by email to coop@icprb.org by 8:00 am for automated processing. Published monitoring reports are at http://icprbcoop.org/products/monitoring-reports.