Situational Awareness (Tuesday, 2026-08-04)
River flow at the USGS Point of Rocks gage remains fairly steady at around 1750 cfs. The past 24 hours saw trace amounts of rainfall, mostly in the southern portions of the basin. According to the Middle Atlantic River Forecast Center predictions, the basin will receive between 0.1 and 0.5 inches of rain over the next 72 hours. The week-long outlook expects a total of approximately 0.5 to 1.0 inches of rain in the basin.
Special Conditions
None
Daily flows:
Little Falls gage flow 2026-08-03: 1577 MGD (2440 cfs)
Little Falls gage flow 2026-08-04: 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 2026-08-03: 1125 MGD (1740 cfs)
Point of Rocks flow 2026-08-04: 1150 MGD (est., based on recently available real-time data) (1780 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-08-03: 1577 MGD (2440 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 (2026-08-03):
Fairfax Water Corbalis withdrawal - Potomac: 100 MGD
WSSC Water Potomac withdrawal: 157 MGD
Washington Aqueduct withdrawal - Great Falls: 117 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 387 MGD
Total net Potomac withdrawal: 381 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1740 cfs
QPR, obs: 1740 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.