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, 2025-09-25)

Submitted by admin1 on Thu, 09/25/2025 - 12:50

Situational Awareness (Thursday, 2025-09-25)

Potomac River flows are expected to rise slightly over the next several days according to Middle Atlantic River Forecast Center (MARFC) predictions. MARFC estimates that total rainfall over the past three days has ranged from 0.25 to 1 inches in most portions of the Potomac watershed above Little Falls. Cumulative precipitation forecasts call for 0.50 to 0.75 inches of rain over the next three days.

Special Conditions

None

Daily Potomac flow and demand update (Tuesday, 2025-09-23)

Submitted by snummer on Tue, 09/23/2025 - 12:54

Situational Awareness (Tuesday, 2025-09-23)
According to the Middle Atlantic River Forecast Center, trace amounts of rainfall feel in western portions of the upper basin over the past 24 hours. The next 72 hours may see between 0.5 and 2 inches of rain. While the week-long outlook expects a total rainfall between 0.75 and 2 inches in the basin.

Special Conditions
None

Daily Potomac flow and demand update (Saturday, 2025-09-20)

Submitted by admin1 on Sat, 09/20/2025 - 12:40

Situational Awareness (Saturday, 2025-09-20):
According to the Middle Atlantic River Forecast Center predictions, the next 3 days may see trace amounts of rain around the edges of the basin. The week-long outlook expects a total of around 0.5–1.5 inches, which is modest compared to the heavy rainfall bands in the central U.S.

Special Conditions:
None

Daily Potomac flow and demand update (Friday, 2025-09-19)

Submitted by admin1 on Fri, 09/19/2025 - 12:24

Situational Awareness (Friday, 2025-09-19)
No precipitation fell in the past 24 hours. Flows at Point of Rocks remain above the 2,000 cfs daily monitoring threshold but are expected to decline in the coming days. Forecasts from the Middle Atlantic River Forecast Center call for light rainfall of 0.01 to 0.1 inch over the next three days, with basin-wide totals of 0.01 to 0.5 inch expected over the week ahead.

Special Conditions
None

Daily Potomac flow and demand update (Tuesday, 2025-09-16)

Submitted by admin1 on Tue, 09/16/2025 - 12:53

Situational Awareness (Tuesday, 2025-09-16)
Minimal precipitation fell in the past 24 hours, and flows continue to decline. The Middle Atlantic River Forecast Center projects little additional rainfall over the next 24 hours. In the 3- to 7-day outlook, basin totals are expected to range from 0.1 to 0.75 inches, with heavier amounts in the lower Potomac and lower overall averages across the basin.

Special Conditions
None

Daily Potomac flow and demand update (Monday, 2025-09-15)

Submitted by snummer on Mon, 09/15/2025 - 12:38

Situational Awareness (Monday, 2025-09-15)
Potomac Rive flow continues to gradually decline. According to the Middle Atlantic River Forecast Center predictions, no rainfall is expected in the next 24 hours. Over the next 3 days, average basin rainfall may be between 0.1 and 0.75 inches, with more rainfall expected in downstream portions of the basin. 

Special Conditions
None

Daily Potomac flow and demand update (Saturday, 2025-09-13)

Submitted by snummer on Sat, 09/13/2025 - 12:43

Situational Awareness (Saturday, 2025-09-13)
According to the Middle Atlantic River Forecast Center, no rain fell in the basin over the past 24 hours. Additionally, no rain is expected to fall in the basin over the next 3 days. The week-long outlook expects a total of approximately 0.1 inches of rain in the basin.

Special Conditions
None