Daily Potomac flow and demand update (Sunday, 2022-10-30)
Over the past day, no significant rainfall occurred in the Potomac basin above Little Falls. According to the MARFC’s 72-hour forecast, total precipitation in the basin will range from 0.01 to 0.25 inches over the next three days, with more rain occurring in the southeastern portions (including the DC area) than in the northwestern portions.
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 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.19 (inches)
Daily flows:
Little Falls gage flow 2022-10-29: 1222 MGD (1890 cfs)
Little Falls gage flow 2022-10-30: 1176 MGD (est., based on recently available real-time data) (1820 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2022-10-29: 1196 MGD (1850 cfs)
Point of Rocks flow 2022-10-30: 1163 MGD (est., based on recently available real-time data) (1800 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2022-10-29):
Fairfax Water Corbalis withdrawal (Potomac): 76 MGD
WSSC Water Potomac withdrawal: 92 MGD
Washington Aqueduct withdrawal: 128 MGD
Loudoun Water withdrawal: 8 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 304 MGD
Total net Potomac withdrawal: 298 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1850 cfs
QPR, obs: 1850 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.