Situational Awareness (Sunday, 2023-10-29)
According to the Middle Atlantic River Forecast Center predictions, the next 24 hours may see 0.1 inches of rain. Over the next week, the average basin rainfall may be around 0.2 inches.
The temporary decrease in flows from yesterday's adjusted operations at Dam No 4 is now visible at the Point of Rocks gage.
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: 0.02 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.03 (inches)
Daily flows:
Little Falls gage flow 2023-10-28: 756 MGD (1170 cfs)
Little Falls gage flow 2023-10-29: 782 MGD (est., based on recently available real-time data) (1210 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-10-28: 866 MGD (1340 cfs)
Point of Rocks flow 2023-10-29: 642 MGD (est., based on recently available real-time data) (993 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2023-10-28: 756 MGD (1170 cfs)
Note: Estimated as gage flow at Little Falls plus Little Falls water supply withdrawal.
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-10-28):
Fairfax Water Corbalis withdrawal - Potomac: 86 MGD
WSSC Water Potomac withdrawal: 135 MGD
Washington Aqueduct withdrawal - Great Falls: 108 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 5 MGD
Loudoun Water Broad Run discharge: 5 MGD
Total Potomac withdrawal: 335 MGD
Total net Potomac withdrawal: 330 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1340 cfs
QPR, obs: 1340 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.