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.

Suspending daily monitoring-Daily Potomac flow and demand update (Tuesday 2021-08-17)

Submitted by admin1 on Tue, 08/17/2021 - 09:00

Up to 2 inches of rain fell in some areas of the basin in the past 24 hours. 1 to 2.5 inches of rain is expected in the next 72 hours.

CO-OP is suspending daily drought monitoring because flow at the US Geological Survey’s gage at Point of Rocks, Maryland has risen above the 2000 cfs monitoring threshold. Thank you for your daily submission of withdrawal and reservoir storage data. Although active monitoring has been discontinued, it is still helpful if you submit data on a daily basis to help us maintain, update, and verify our forecast tools.

Daily Potomac flow and demand update (Monday 2021-08-16)

Submitted by admin1 on Mon, 08/16/2021 - 09:00

Up to half an inch of precipitation fell in some areas of the basin in the past 24 hours. Over the next three days, one to four inches of rain is expected in the basin depending on location. Daily flows: Little Falls gage flow 2021-08-15: 1480 MGD (2290 cfs) Little Falls gage flow 2021-08-16: 1409 MGD (est., based on recently available real time data) (2180 cfs) Note: Gage flow at Little Falls is measured after water supply withdrawals.

Daily Potomac flow and demand update (Wednesday 2021-08-11)

Submitted by admin1 on Wed, 08/11/2021 - 09:00

River flows have responded to yesterday’s storm events. Precipitation in the basin over the past 24 hours was scattered, with trace amounts in most areas but up to an inch and a half in some locations. The National Weather Service forecast calls for accumulations of 0.10 to 0.50 inches in the basin during the next three days.

Daily Potomac flow and demand update (Tuesday 2021-08-10)

Submitted by admin1 on Tue, 08/10/2021 - 09:00

Scattered locations across the upper Potomac Basin received between 0.1 and 0.5 inches of rain over the past 24 hours. Small portions of the basin near Washington D.C received up to 2 inches of rain. 0.1 to 1.5 inches of rain are expected over the next 3 days.
Adjustments made yesterday to the Little Falls gage’s rating curve resulted in discharge values lower than previously reported.

Daily Potomac flow and demand update (Sunday 2021-08-08)

Submitted by admin1 on Sun, 08/08/2021 - 09:00

Widely scattered locations across the upper basin received trace amounts of rain (up to 0.1 inches) over the past 24 hours. Precipitation totaling 0.01 to 0.25 inches is expected in the upper basin over the next three days. Higher amounts of half an inch are also possible in scattered locations in Pennsylvania and along the Virginia-West Virginia border. Flow at Point of Rocks is holding steady above 1500 cfs.