Situational Awareness (Tuesday, 2025-09-30)
Trace amounts of rain fell in the lower basin yesterday. According to the Middle Atlantic River Forecast Center predictions, no appreciable rain is expected over the next five days.
Special Conditions
The USGS website appears to be down and gage data are not available at this time.
Daily flows:
Little Falls gage flow 2025-09-29: N/A
Little Falls gage flow 2025-09-30: N/A
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2025-09-29: N/A
Point of Rocks flow 2025-09-30: N/A
Yesterday's estimated daily flows:
Great Falls estimated flow 2025-09-29: N/A
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 (2025-09-29):
Fairfax Water Corbalis withdrawal - Potomac: 108 MGD
WSSC Water Potomac withdrawal: 144 MGD
Washington Aqueduct withdrawal - Great Falls: 129 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 11 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 392 MGD
Total net Potomac withdrawal: 385 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: N/A
QPR, obs: N/A
QPR, WS: N/A
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.