Situational Awareness (Sunday, 2026-09-20):
According to current precipitation forecasts, accumulated rainfall in the Potomac watershed will be approximately 1.5 to 2 inches over the next 3 days and 2 to 3 inches over the next 5 to 7 days, with higher amounts possible in portions of the watershed.
Special Conditions:
Julie Fritz of the U.S. Army Corps of Engineers, Baltimore District, informed us that the final scheduled whitewater release from Savage River Dam for 2026 is Saturday, September 26, 2026. The 2026 water quality release schedule for Jennings Randolph and Savage reservoirs is available on the, https://water.usace.army.mil/office/nab/releases/north-branch.
Daily flows:
Little Falls gage flow 2026-09-19: 885 MGD (1370 cfs)
Little Falls gage flow 2026-09-20: 840 MGD (est., based on recently available real-time data) (1300 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-09-19: 1060 MGD (1640 cfs)
Point of Rocks flow 2026-09-20: 1086 MGD (est., based on recently available real-time data) (1680 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-09-19: 885 MGD (1369 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 (2026-09-19):
Fairfax Water Corbalis withdrawal - Potomac: 107 MGD
WSSC Water Potomac withdrawal: 134 MGD
Washington Aqueduct withdrawal - Great Falls: 119 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 372 MGD
Total net Potomac withdrawal: 365 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1640 cfs
QPR, obs: 1640 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.