Situational Awareness (Sunday, 2026-08-09)
Flows at the Point of Rocks gage has stayed above 2,000 cfs and are predicted to remain so through at least the beginning of this week. Additionally, according to the Middle Atlantic River Forecast Center predictions, the next 3 days are forecasted to see between 0.1 and 0.5 inches of rain. As such, CO-OP is suspending its daily drought monitoring and reporting. This phase of CO-OP's drought response is triggered when daily flows at USGS's Point of Rocks gage fall below 2,000 cfs.
Thank you to all of the organizations and water suppliers for your continued support and cooperation.
Special Conditions
The National Park Service has informed us that the annual off-water inspection at Potomac Dam No. 4 in Washington County, MD, will take next week (Tuesday, August 11, 2026). During this time, the hydroelectric operator – Eagle Creek Renewables will be diverting water off of the run-of-river dam crest through their powerhouse turbines. This will cause intra-daily flow fluctuations at the Point of Rocks gage.
Daily flows:
Little Falls gage flow 2026-08-08: 1596 MGD (2470 cfs)
Little Falls gage flow 2026-08-09: 1312 MGD (est., based on recently available real-time data) (2030 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-08-08: 1396 MGD (2160 cfs)
Point of Rocks flow 2026-08-09: 1907 MGD (est., based on recently available real-time data) (2950 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-08-08: 1596 MGD (2469 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 (2026-08-08):
Fairfax Water Corbalis withdrawal - Potomac: 101 MGD
WSSC Water Potomac withdrawal: 107 MGD
Washington Aqueduct withdrawal - Great Falls: 129 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 349 MGD
Total net Potomac withdrawal: 343 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2160 cfs
QPR, obs: 2160 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.