Situational Awareness (Wednesday, 2025-11-05)
According to the Middle Atlantic River Forecast Center, no rain fell in the basin over the past 24 hours. Over the next 3 days, the average basin rainfall may be up to 0.25 inches. With the minimal amount of rain expected over the next few days, Potomac River flows at Point of Rocks are expected to fall back below 2000 cfs, the CO-OP Daily Drought Monitoring threshold.
Special Conditions
Washington Aqueduct sent us a notification that they planned to drain their old conduit on Monday 11/3 for an inspection and discharge drainage via their Maryland outfalls and pump from the Little Falls Pumping Station throughout this week.
Daily flows:
Little Falls gage flow 2025-11-04: 1932 MGD (2990 cfs)
Little Falls gage flow 2025-11-05: 1777 MGD (est., based on recently available real-time data) (2750 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-11-04: 1745 MGD (2700 cfs)
Point of Rocks flow 2025-11-05: 1706 MGD (est., based on recently available real-time data) (2640 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-11-04: 1977 MGD (3059 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 (2025-11-04):
Fairfax Water Corbalis withdrawal - Potomac: 89 MGD
WSSC Water Potomac withdrawal: 130 MGD
Washington Aqueduct withdrawal - Great Falls: 87 MGD
Washington Aqueduct withdrawal - Little Falls: 45 MGD
Loudoun Water withdrawal: 11 MGD
Loudoun Water Broad Run discharge: 8 MGD
Total Potomac withdrawal: 361 MGD
Total net Potomac withdrawal: 354 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2700 cfs
QPR, obs: 2700 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.