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.

Afternoon Potomac flow and demand update (Wednesday, 2023-08-30)

Submitted by admin1 on Wed, 08/30/2023 - 14:20

Current river flow at Little Falls is about 728 cfs (471 MGD) and has remained above 700 cfs for the past 12 hours.

Daily flows:

Little Falls gage flow 2023-08-29: 408 MGD (632 cfs)

Little Falls gage flow 2023-08-30: 471 MGD (est., based on recently available real-time data) (728 cfs)

Note: Gage flow at Little Falls is measured after water supply withdrawals.

Morning Potomac flow and demand update (Wednesday, 2023-08-30)

Submitted by admin1 on Wed, 08/30/2023 - 08:36

According to National Weather Service predictions, no rainfall is expected over the next 7 days.

At 3 P.M. yesterday, Washington Aqueduct initiated a proactive load shift of 65 MGD to the Little Falls intake to increase Potomac flow between Great Falls and Little Falls. The recently observed, significant flow fluctuations at Point of Rocks related to hydroelectric dam operations have stabilized. We believe that hydro-dam impacts on flow at Little Flows will not be significant over the next few days.

Morning Potomac flow and demand update (Wednesday, 2023-08-30)

Submitted by admin1 on Wed, 08/30/2023 - 08:22

According to National Weather Service predictions, no rainfall is expected over the next 7 days.

 

At 3 P.M. yesterday, Washington Aqueduct initiated a proactive load shift of 65 MGD to the Little Falls intake to increase Potomac flow between Great Falls and Little Falls. The recently observed, significant flow fluctuations at Point of Rocks related to hydroelectric dam operations have stabilized. We believe that hydro-dam impacts on flow at Little Flows will not be significant over the next few days.

Morning Potomac flow and demand update (Tuesday, 2023-08-29)

Submitted by admin1 on Tue, 08/29/2023 - 08:38

Flows at Little Falls are declining, and a Washington Aqueduct load shift to the Little Falls pumps may be needed today. Based on Middle Atlantic River Forecast Center forecasts, we expect ¼ to 1 inch of rainfall in the basin over the next 72 hours, with a basin-wide average of perhaps ½. The longer term forecast is not promising.

Afternoon Potomac flow and demand update (Monday, 2023-08-28):

Submitted by admin1 on Mon, 08/28/2023 - 14:49

River flow at Little Falls has not decreased as drastically as projected over the past 24 hours. Current river flow at Little Falls is about 778 cfs (503 MGD) and predicted to decrease over the next 24 hours. Operations at Dams 4 and 5 are still affecting flows at Little Falls and we are closely watching whether flows will drop below 500 cfs.

 

Daily flows:

Little Falls gage flow 2023-08-27: 550 MGD (851 cfs)

Daily Potomac flow and demand update (Monday, 2023-08-28)

Submitted by admin1 on Mon, 08/28/2023 - 08:47

Minimal rain fell in the basin over the past 24 hours. Expected rainfall over the next three days ranges from 0.25 to 1 inch according to the Middle Atlantic River Forecast Center. Hydropower operations continue to affect river flows. Large fluctuations in river flows are observed at the Shepherdstown and Point of Rocks gages and are expected to affect river flows at Great Falls and Little Falls. 

 

Recent basin-wide average precipitation (above Little Falls):

Morning Potomac flow and demand update (Sunday, 2023-08-27)

Submitted by admin1 on Sun, 08/27/2023 - 08:51

No rain fell in the basin over the past 24 hours.  Rainfall is expected over the next 3 days according to the Middle Atlantic River Forecast Center, ranging from 0.1 to 1 inch.

Hydropower operations continue to affect river flows. Large fluctuations in river flows are observed at the Shepherdstown and at the Point of Rocks gage and are expected to affect river flows at Great Falls and Little Falls.