Situational Awareness (Thursday, 2024-08-08)
Today, CO-OP is suspending its daily drought monitoring and reporting. This phase of CO-OP’s drought response is triggered when daily Potomac River flow at the USGS’s Point of Rocks gage falls below 2000 cubic feet per second (cfs). Yesterday’s flow rose above that threshold and is expected to continue rising due to the arrival of heavy rain from tropical storm Debby. The Middle Atlantic River Forecast Center predicts that precipitation in the portion of the Potomac basin upstream of the USGS’s Little Falls gage will average 0.9 inches over the next day and 4 inches over the next 3 days. Though there is always a chance that forecasted rain doesn’t materialize, we are fairly confident that drought conditions in the Potomac basin will be alleviated for at least several weeks, based on available information.
We want to express our appreciation to all of the people who provide us with the data we use in our reports: Washington metropolitan area water suppliers at Fairfax Water, Washington Aqueduct, WSSC Water, and Loudoun Water, and also our partner organizations, the US Geological Survey and the Middle Atlantic River Forecast Center.
Special Conditions
None
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: 0.75 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.88 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 1.75 (inches)
Daily flows:
Little Falls gage flow 2024-08-07: 924 MGD (1430 cfs)
Little Falls gage flow 2024-08-08: 1713 MGD (est., based on recently available real-time data) (2650 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2024-08-07: 1680 MGD (2600 cfs)
Point of Rocks flow 2024-08-08: 2921 MGD (est., based on recently available real-time data) (4520 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2024-08-07: 980 MGD (1516 cfs)
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 (2024-08-07):
Fairfax Water Corbalis withdrawal - Potomac: 119 MGD
WSSC Water Potomac withdrawal: 141 MGD
Washington Aqueduct withdrawal - Great Falls: 101 MGD
Washington Aqueduct withdrawal - Little Falls: 56 MGD
Loudoun Water withdrawal: 14 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 430 MGD
Total net Potomac withdrawal: 424 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2600 cfs
QPR, obs: 2600 cfs
QPR, WS: 0 cfs