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 (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

Daily Potomac flow and demand update (Thursday, 2025-10-09)

Submitted by admin1 on Thu, 10/09/2025 - 12:46

Situational Awareness (Thursday, 2025-10-09)
Potomac River flows are holding relatively steady. No appreciable amount of rain fell in the Potomac watershed yesterday. According to the Middle Atlantic River Forecast Center, 1/10 to 1/4 inch is expected over the next three days in most parts of the watershed, and an average accumulation of more than 1/2 inch is expected over the next 4 days.

Special Conditions
None

Daily Potomac flow and demand update (Tuesday, 2025-10-07)

Submitted by hmoltz on Wed, 10/08/2025 - 13:09

Situational Awareness (Tuesday, 2025-10-07)

No precipitation was recorded in the basin over the past 24 hours. The Middle Atlantic River Forecast Center predicts 0.25-0.75 inches of rain across much of the basin over the next three days, with localized totals up to 1.5 inches possible. 

 

Special Conditions

None

 

Daily flows:

Little Falls gage flow 2025-10-06: 918 MGD (1420 cfs)

Daily Potomac flow and demand update (Monday, 2025-10-06)

Submitted by admin1 on Mon, 10/06/2025 - 13:27

Situational Awareness (Monday, 2025-10-06)
According to Middle Atlantic River Forecast Center predictions, no rain fell in the Potomac watershed over the past 3 days, but approximately 1/2 inch is expected over the next 3 days.

Special Conditions
USGS stream gage website pages will not be updated due to the lapse in federal funding. However, at this time updated streamflow data continues to be available.

Daily Potomac flow and demand update (Sunday, 2025-10-05)

Submitted by admin1 on Sun, 10/05/2025 - 02:47

Situational Awareness (Sunday, 2025-10-05)
No rainfall has been recorded over the past 24 hours. According to the Middle Atlantic River Forecast Center, basin rainfall over the next three days is expected to range from 0.25 to 0.75 inches. The seven-day outlook indicates total rainfall of up to 0.75 inches in parts of the basin.

Special Conditions
None

Daily Potomac flow and demand update (Saturday, 2025-10-04)

Submitted by admin1 on Sat, 10/04/2025 - 02:49

Situational Awareness (Saturday, 2025-10-04)
There has been no rainfall over the past 24 hours. According to the Middle Atlantic River Forecast Center, average basin rainfall over the next three days is expected to remain near zero inches. The seven-day outlook indicates up to 0.75 inches of total rainfall in parts of the basin.

Special Conditions
U.S. Drought Monitor percent coverage of the Potomac for D1 and greater is currently 59 percent. 

Daily Potomac flow and demand update (Thursday, 2025-10-02)

Submitted by admin1 on Thu, 10/02/2025 - 13:03

Situational Awareness (Thursday, 2025-10-02)
No rainfall fell in the Potomac watershed yesterday according to Middle Atlantic River Forecast Center (MARFC) estimates. Dry conditions are predicted to persist in the watershed for the next five days, according to forecasts from MARFC and from the National Weather Services Weather Prediction Center.  

Special Conditions

Daily Potomac flow and demand update (Wednesday, 2025-10-01)

Submitted by admin1 on Wed, 10/01/2025 - 12:48

Situational Awareness (Wednesday, 2025-10-01)
Potomac River flows have been hovering around 2000 cfs due to the recent rain, but no significant rainfall is expected over the next 10 days. According to information from the Middle Atlantic River Forecast Center, trace amounts to 1/4 inch of rain fell in the southern half of the Potomac watershed over the past 24 hours and no rain is forecast over the next 3 days.