Situational Awareness (Friday, 2025-09-26)
Widespread precipitation fell across the basin over the past 24 hours, ranging from trace amounts to an inch in some areas. According to the Middle Atlantic River Forecast Center predictions, the next 3 days may see additional rain between trace amounts and 0.75 inches.
Special Conditions
A whitewater release from Savage River Dam is scheduled for tomorrow, Saturday, September 27th. The release is scheduled to be 1,000 cfs from 10am to 4pm. Additional information can be found at https://water.usace.army.mil/office/nab/nbrelease.
Daily flows:
Little Falls gage flow 2025-09-25: 1125 MGD (1740 cfs)
Little Falls gage flow 2025-09-26: 1034 MGD (est., based on recently available real-time data) (1600 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-09-25: 1066 MGD (1650 cfs)
Point of Rocks flow 2025-09-26: 1176 MGD (est., based on recently available real-time data) (1820 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-09-25: 1125 MGD (1741 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 (2025-09-25):
Fairfax Water Corbalis withdrawal - Potomac: 88 MGD
WSSC Water Potomac withdrawal: 122 MGD
Washington Aqueduct withdrawal - Great Falls: 145 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 368 MGD
Total net Potomac withdrawal: 361 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1650 cfs
QPR, obs: 1650 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://www.nab-wc.usace.army.mil/nab/poto.html; See US Army Corps of Engineers North Branch Potomac River and Savage River page for scheduled releases - https://www.nab-wc.usace.army.mil/nab/northBranch.html.
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.