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 (Saturday, 2025-12-06)

Submitted by admin1 on Sat, 12/06/2025 - 13:30

Situational Awareness (Saturday, 2025-12-06):
Yesterday, 0 to 0.25 inches of precipitation fell across the lower half of the basin. According to the Middle Atlantic River Forecast Center, the week-long outlook calls for up to 0.1 inches of total rainfall basinwide, following a five-day stretch with no precipitation..

Special Conditions:
None

Daily Potomac flow and demand update (Friday, 2025-12-05)

Submitted by admin1 on Fri, 12/05/2025 - 13:51

Situational Awareness (Friday, 2025-12-05):
According to observations from the Middle Atlantic River Forecast Center, between 0.01 and 0.1 inches of precipitation fell across the basin yesterday. The seven-day outlook indicates a similar basinwide total of about 0.01 to 0.1 inches, with isolated areas in the western part of the basin possibly receiving up to 0.5 inches. Daily average flow in the Potomac River remains slightly above 2,000 cfs, the threshold for daily monitoring.

Special Conditions:
None

Daily Potomac flow and demand update (Thursday, 2025-12-04)

Submitted by admin1 on Thu, 12/04/2025 - 13:09



Situational Awareness (Thursday, 2025-12-04)
Dry conditions persist. According to information from the Middle Atlantic River Forecast Center, no rain fell in the Potomac watershed during the past day and an average accumulation of only 1/4 inch is expected over the next 10 days.

Special Conditions
None

Daily flows:
Little Falls gage flow 2025-12-03: 1739 MGD (2690 cfs)

Daily Potomac flow and demand update (Wednesday, 2025-12-03) hmoltz Wed, 12/03/2025 - 13:10

Situational Awareness (Wednesday, 2025-12-03)
Over the past 24 hours, the basin received between a trace and 0.75 inches of precipitation. According to the Middle Atlantic River Center, trace amounts of precipitation are expected across the basin over the next 3 days.

Special Conditions
None

Daily Potomac flow and demand update (Tuesday, 2025-12-02)

Submitted by snummer on Tue, 12/02/2025 - 13:33

Situational Awareness (Tuesday, 2025-12-02)
According to the Middle Atlantic River Forecast Center, between 0.1 and 0.25 inches of precipitation fell in the basin over the past 24 hours.  Over the next 3 days, the average basin precipitation may be between trace amounts and 1 inch, with eastern portions of the basin expecting the greatest accumulation. 

Special Conditions
None

Daily Potomac flow and demand update (Saturday, 2025-11-29)

Submitted by admin1 on Sat, 11/29/2025 - 13:45

Situational Awareness (Saturday, 2025-11-29)
According to information from the Middle Atlantic River Forecast Center, no appreciable precipitation fell in the Potomac watershed over the past 24 hours. An average accumulation of approximately 1/2 inch is expected in the watershed over the next 4 days.

Special Conditions
None

Daily flows:
Little Falls gage flow 2025-11-28: 1435 MGD (2220 cfs)

Daily Potomac flow and demand update (Friday, 2025-11-28)

Submitted by admin1 on Fri, 11/28/2025 - 13:14

Situational Awareness (Friday, 2025-11-28):
Point of Rocks flows remain above the 2,000 cfs threshold for daily monitoring. According to the Middle Atlantic River Forecast Center, no rain fell in the basin yesterday. Over the next five to seven days, average basin rainfall is expected to total up to 1 inch or more across the basin.

Special Conditions:
None

Daily Potomac flow and demand update (Thursday, 2025-11-27)

Submitted by admin1 on Thu, 11/27/2025 - 13:10

Situational Awareness (Thursday, 2025-11-27):
Point of Rocks flows rose above the 2,000 cfs threshold for daily monitoring due to recent precipitation. According to the Middle Atlantic River Forecast Center, only trace amounts of rain fell in parts of the basin yesterday. Over the next five days, average basin rainfall is expected to range from 0.1 to 0.5 inches. The week-long outlook suggests up to 1 inch of rainfall across the basin.