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 (Monday, 2025-12-15)

Submitted by snummer on Mon, 12/15/2025 - 14:09

Situational Awareness (Monday, 2025-12-15)
According to the Middle Atlantic River Forecast Center, trace amounts of precipitation fell in eastern portions of the basin over the past 24 hours. Over the next 3 days, no precipitation is anticipated. However, the week-long outlook expects a total of approximately 0.5 inches of precipitation in the basin.

Daily Potomac flow and demand update (Saturday, 2025-12-13)

Submitted by admin1 on Sat, 12/13/2025 - 13:35

Situational Awareness (Saturday, 2025-12-13)
River flows continue to slowly decline. According to information from the Middle Atlantic River Forecast Center, no significant amounts of rain fell in the Potomac watershed during the past 24 hours. An average accumulation of less than 1/4 inch is expected over the next 3 days.

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

Submitted by admin1 on Fri, 12/12/2025 - 13:01

Situational Awareness (Friday, 2025-12-12):
According to the Middle Atlantic River Forecast Center, scattered trace amounts of precipitation fell in the western basin over the past 24 hours. Over the next three days, up to 0.25 inches of rain is expected across the basin, with up to 0.5 inches possible in and downstream of the DC area.

Special Conditions:
None

Daily Potomac flow and demand update (Wednesday, 2025-12-10)

Submitted by hmoltz on Wed, 12/10/2025 - 13:37

Situational Awareness (Wednesday, 2025-12-10)
According to the Middle Atlantic River Forecast Center, no measurable precipitation was recorded in the basin over the past 24 hours.  The next 3 days may see trace amounts of precipitation, with higher amounts possible in the western portion of the basin. 

Special Conditions
None

Daily Potomac flow and demand update (Tuesday, 2025-12-09)

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

Situational Awareness (Tuesday, 2025-12-09)
Dry conditions persist. According to information from the Middle Atlantic River Forecast Center, the southern portion of the Potomac watershed received a small amount of precipitation during the past 24 hours, ranging from 0.01 to 0.1 inches. A small amount of precipitation is expected in the northern portion of the watershed over the next 3 days.

Special Conditions

Daily Potomac flow and demand update (Monday, 2025-12-08)

Submitted by admin1 on Mon, 12/08/2025 - 14:11

Situational Awareness (Monday, 2025-12-08)
According to information from the Middle Atlantic River Forecast Center, the southern portion of the Potomac watershed received a small amount of precipitation during the past 24 hours. Average accumulations of about 1/10 of an inch are expected over the next 3 days.

Special Conditions
None

Daily flows:
Little Falls gage flow 2025-12-07: 1480 MGD (2290 cfs)

Daily Potomac flow and demand update (Sunday, 2025-12-07)

Submitted by snummer on Sun, 12/07/2025 - 13:47

Situational Awareness (Sunday, 2025-12-07)
No precipitation fell in the basin over the past 24 hours. According to the Middle Atlantic River Forecast Center predictions, the next 3 days may see 0.1 inches of rain in the lower portions of the basin.  The week-long outlook expects a total of approximately 0.5 inches of rain in the basin.

Special Conditions
None

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