Situational Awareness (Wednesday, 2023-10-25)
Trace amounts of rainfall have fallen in the basin over the past 3 days. In addition, the week-long outlook expects a total of approximately 0.1 inches of rain in the basin according to the Middle Atlantic River Forecast Center.
Recent basin-wide average precipitation (above Little Falls):
(based on CO-OP's Low Flow Forecast System analysis of Middle Atlantic River Forecast Center (MARFC) gridded multisensor precipitation estimates)
Yesterday's area-weighted average basin precipitation: 0 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.01 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.32 (inches)
Daily flows:
Little Falls gage flow 2023-10-24: 821 MGD (1270 cfs)
Little Falls gage flow 2023-10-25: 808 MGD (est., based on recently available real-time data) (1250 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-10-24: 892 MGD (1380 cfs)
Point of Rocks flow 2023-10-25: 873 MGD (est., based on recently available real-time data) (1350 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-10-24):
Fairfax Water Corbalis withdrawal - Potomac: 89 MGD
WSSC Water Potomac withdrawal: 132 MGD
Washington Aqueduct withdrawal - Great Falls: 31 MGD
Washington Aqueduct withdrawal - Little Falls: 91 MGD
Loudoun Water withdrawal: 5 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 348 MGD
Total net Potomac withdrawal: 341 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1380 cfs
QPR, obs: 1380 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 – see https://www.weather.gov/erh/mmefs_marfc?id=PORM2&model=NAEFS.
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.