Situational Awareness (Friday, 2025-10-03)
No precipitation was observed in the Potomac basin over the past 24 hours. The Middle Atlantic River Forecast Center projects little to no rainfall over the next three days. The seven-day outlook indicates a total of up to 0.5 inches of rain across the basin.
Special Conditions
Messages have been posted on USGS stream gage website pages reporting that they will not be updated due to the lapse in federal funding. However, at this time updated streamflow data continues to be available. Mary K. Foley, Director of the USGS’s MD-DE-DC Water Science Center, sent out a message yesterday saying that "During this period, USGS will continue critical activities necessary to protect life and property, such as the operation and maintenance of streamgages and other essential monitoring systems. These vital functions are being maintained to ensure the uninterrupted delivery of public safety information."
Daily flows:
Little Falls gage flow 2025-10-02: 1144 MGD (1770 cfs)
Little Falls gage flow 2025-10-03: 1144 MGD (est., based on recently available real-time data) (1770 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-10-02: 1241 MGD (1920 cfs)
Point of Rocks flow 2025-10-03: 1202 MGD (est., based on recently available real-time data) (1860 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-10-02: 1144 MGD (1770 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 (2025-10-02):
Fairfax Water Corbalis withdrawal - Potomac: 99 MGD
WSSC Water Potomac withdrawal: 132 MGD
Washington Aqueduct withdrawal - Great Falls: 143 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 386 MGD
Total net Potomac withdrawal: 379 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1920 cfs
QPR, obs: 1920 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.