Situational Awareness (Monday, 2025-09-29)
Flows have moderately increased over the past week. Flow at Point of Rocks is currently hovering around 2,000 cfs. No rainfall was recorded in the basin over the past 24 hours, according to the Middle Atlantic River Forecast Center. Over the next three days, 0.01 to 0.1 inches of rain are expected, with no substantial rainfall forecast for the week.
Special Conditions
None
Daily flows:
Little Falls gage flow 2025-09-28: 1293 MGD (2000 cfs)
Little Falls gage flow 2025-09-29: 1222 MGD (est., based on recently available real-time data) (1890 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-09-28: 1254 MGD (1940 cfs)
Point of Rocks flow 2025-09-29: 1306 MGD (est., based on recently available real-time data) (2020 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-09-28: 1293 MGD (2000 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 (2025-09-28):
Fairfax Water Corbalis withdrawal - Potomac: 106 MGD
WSSC Water Potomac withdrawal: 132 MGD
Washington Aqueduct withdrawal - Great Falls: 135 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 385 MGD
Total net Potomac withdrawal: 378 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1940 cfs
QPR, obs: 1940 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.