Situational Awareness (Saturday, 2026-10-10)
No rainfall was observed over the past 24 hours in the Potomac basin upstream of Little Falls, Maryland. 1 to 3 inches of rain is expected over the next three days.
Special Conditions
Intra-daily flow fluctuations at Potomac River gages, including Point of Rocks, are occurring due to upstream dam operations associated with eel passage.
Daily flows:
Little Falls gage flow 2026-10-09: 924 MGD (1430 cfs)
Little Falls gage flow 2026-10-10: 885 MGD (est., based on recently available real-time data) (1370 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-10-09: 905 MGD (1400 cfs)
Point of Rocks flow 2026-10-10: 995 MGD (est., based on recently available real-time data) (1540 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-10-09: 1012 MGD (1566 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 (2026-10-09):
Fairfax Water Corbalis withdrawal - Potomac: 104 MGD
WSSC Water Potomac withdrawal: 155 MGD
Washington Aqueduct withdrawal - Great Falls: 35 MGD
Washington Aqueduct withdrawal - Little Falls: 88 MGD
Loudoun Water withdrawal: 7 MGD
Loudoun Water Broad Run discharge: 8 MGD
Total Potomac withdrawal: 389 MGD
Total net Potomac withdrawal: 381 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1400 cfs
QPR, obs: 1400 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.