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, 2025-12-04)

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 (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.

Daily Potomac flow and demand update (Saturday, 2025-11-22)

Submitted by admin1 on Sat, 11/22/2025 - 13:32

Situational Awareness (Saturday, 2025-11-22)
Potomac River flows have increased slightly. According to information from the Middle Atlantic River Forecast Center, cumulative precipitation in the watershed ranged from 1/10 to 1/2 inches over the past three days. A 1/10th of an inch or less of rainfall is expected over the next three days.

Special Conditions
None

Daily flows: