Monitoring Reports

During periods of drought, the Cooperative Water Supply Operations on the Potomac (CO-OP) helps manage the Washington metropolitan area water supply system by coordinating withdrawals from the Potomac River and off-river reservoirs and recommending releases from upstream reservoirs when forecasted flow in the river is not sufficient to meet expected needs. These needs include water demands and an environmental flow-by of 100 million gallons per day (MGD) on the Potomac River at Little Falls dam near Washington, D.C.
Daily Potomac flow and demand update (Thursday, 2025-10-23) snummer Thu, 10/23/2025 - 12:59

Situational Awareness (Thursday, 2025-10-23)
According to the Middle Atlantic River Forecast Center, no rainfall occurred in the basin over the past 24 hours.  Additionally, no rainfall is expected in the next 3 days.  The week-long outlook expects a total of approximately 0.75 to 1.5 inches of rain in the basin, with localized areas predicted to see up to 2 inches of rain. 

Special Conditions
None

Daily Potomac flow and demand update (Friday, 2025-10-17)

Submitted by admin1 on Fri, 10/17/2025 - 12:38

Situational Awareness (Friday, 2025-10-17):
No rain was observed yesterday. The Middle Atlantic River Forecast Center expects 0.25–0.75 inches of rain over the next 3 days, with most areas likely getting 0.25–0.5 inches. The week-long forecast predicts similar totals, though some additional locations could see up to 0.75 inches.

Special Conditions:
Most notably, areas of Severe Drought (31.9 percent of the basin) have expanded across portions of the West Virginia panhandle and western Virginia.

Daily Potomac flow and demand update (Thursday, 2025-10-16)

Submitted by admin1 on Thu, 10/16/2025 - 12:14

Situational Awareness (Thursday, 2025-10-16)
Dry conditions persist. No rain is forecast for the Potomac watershed over the next three days according to the Middle Atlantic River Forecast Center.

Special Conditions
None

Daily flows:
Little Falls gage flow 2025-10-15: 1079 MGD (1670 cfs)
Little Falls gage flow 2025-10-16: 982 MGD (est., based on recently available real-time data) (1520 cfs)

Daily Potomac flow and demand update (Tuesday, 2025-10-14)

Submitted by admin1 on Tue, 10/14/2025 - 12:53

Situational Awareness (Tuesday, 2025-10-14)
Potomac River flows are holding relatively steady. According to information provided by the Middle Atlantic River Forecast Center, the Potomac watershed received a small amount of rainfall over the past 24 hours - 1/100 to 1/10 of an inch in most areas in the northern portion of the watershed and little or no rain in the southern portion. No rain is forecast for the watershed over the next 3 days.

Daily Potomac flow and demand update (Monday, 2025-10-13)

Submitted by admin1 on Mon, 10/13/2025 - 12:52

Situational Awareness (Monday, 2025-10-13)
The impact of the recent storm system has been disappointing from a water supply point of view. According to information from the Middle Atlantic River Forecast Center, accumulations of roughly 1/10 to 2/10 of an inch of precipitation fell in the Potomac watershed over the past 72 hours, and a watershed average of approximately 2/10 of an inch is expected over the next 3 days.

Special Conditions

Daily Potomac flow and demand update (Friday, 2025-10-10)

Submitted by admin1 on Fri, 10/10/2025 - 12:40

Situational Awareness (Friday, 2025-10-10)
No rainfall was observed over the past 24 hours. According to forecasts from the Middle Atlantic River Forecast Center, average basin rainfall over the next three days is expected to range from 0.25 to 1 inch. The week-long outlook anticipates similar or slightly higher totals across the basin.

Special Conditions
None