Situational Awareness (Thursday, 2025-11-27):
Point of Rocks flows rose above the 2,000 cfs threshold for daily monitoring due to recent precipitation. According to the Middle Atlantic River Forecast Center, only trace amounts of rain fell in parts of the basin yesterday. Over the next five days, average basin rainfall is expected to range from 0.1 to 0.5 inches. The week-long outlook suggests up to 1 inch of rainfall across the basin.
Special Conditions:
Warm Thanksgiving wishes from ICPRB CO-OP, and thank you for all you do throughout the year and for your continued support in daily monitoring.
Daily flows:
Little Falls gage flow 2025-11-26: 1357 MGD (2100 cfs)
Little Falls gage flow 2025-11-27: 1370 MGD (est., based on recently available real-time data) (2120 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-11-26: 1409 MGD (2180 cfs)
Point of Rocks flow 2025-11-27: 1629 MGD (est., based on recently available real-time data) (2520 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-11-26: 1357 MGD (2100 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 (2025-11-26):
Fairfax Water Corbalis withdrawal - Potomac: 77 MGD
WSSC Water Potomac withdrawal: 144 MGD
Washington Aqueduct withdrawal - Great Falls: 115 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 10 MGD
Loudoun Water Broad Run discharge: 8 MGD
Total Potomac withdrawal: 346 MGD
Total net Potomac withdrawal: 338 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2180 cfs
QPR, obs: 2180 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.