Situational Awareness (Sunday, 2026-02-01)
According to information from the Middle Atlantic River Forecast Center, no precipitation fell in the Potomac basin during the past 24 hours. Small amounts - 0.01 to 0.10 inches - are predicted throughout the basin over the next 3 days, with totals up to 0.25 inches possible along the far western edge of the basin.
Special Conditions
Flow data at Point of Rocks is currently unavailable due to the presence of ice. For more information about ice effects on streams, see Water-Supply Paper 2175: Measurement and Computation of Streamflow: Volume 2. Computation of Discharge pages 360-376 (WSP 2175). Potomac River flow values for Loudoun Water’s drought operations protocol were estimated based on information from the MARFC’s River Observations and Forecasts webpages.
Daily flows:
Little Falls gage flow 2026-01-31: 1377 MGD (2130 cfs)
Little Falls gage flow 2026-02-01: 1280 MGD (est., based on recently available real-time data) (1980 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-01-31: Not available due to ice
Point of Rocks flow 2026-02-01: Not available due to ice
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-01-31: 1377 MGD (2131 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 (2026-01-31):
Fairfax Water Corbalis withdrawal - Potomac: 82 MGD
WSSC Water Potomac withdrawal: 149 MGD
Washington Aqueduct withdrawal - Great Falls: 119 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 8 MGD
Loudoun Water Broad Run discharge: 9 MGD
Total Potomac withdrawal: 358 MGD
Total net Potomac withdrawal: 349 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
* Estimated from the MARFC’s River Observations and Forecasts webpages.
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 .