The basin received almost a ¼ inch of rain over the last 24 hours. Little rain is expected in the portion of the watershed above Little Falls over the next three days. According to Middle Atlantic River Forecast Center ensemble flow forecasts, flow at Point of Rocks is expected to remain above 1800 cfs over the weekend.
Though flow conditions are not yet of great concern, we intend to continue daily monitoring reports over the weekend, and would appreciate it if you can continue sending withdrawal and reservoir storage data.
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 multi-sensor precipitation estimates)
Yesterday's area-weighted average basin precipitation: 0.23 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.26 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.37 (inches)
Daily flows:
Little Falls gage flow 2021-07-29: not available
Little Falls gage flow 2021-07-30: 1642 MGD (est., based on recently available real time data) (2540 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2021-07-29: 1150 MGD (1780 cfs)
Point of Rocks flow 2021-07-30: 1189 MGD (est., based on recently available real time data) (1840 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2021-07-29):
Fairfax Water Corbalis withdrawal (Potomac): 111 MGD
WSSC Water Potomac withdrawal: 120 MGD
Washington Aqueduct withdrawal: 147 MGD
Loudoun Water withdrawal: 11 MGD
Loudoun Water Broad Run discharge: 4 MGD
Total Potomac withdrawal: 389 MGD
Total net Potomac withdrawal: 385 MGD
Loudoun Water drought operations protocol for today based on yesterday’s river flow values:
QPR: 1780 cfs
QPR, obs: 1780 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.