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, 2022-10-28)

Submitted by admin1 on Sat, 10/29/2022 - 12:32

Stream flows in the Potomac basin continue to slowly decline. According to the National Weather Service’s 7-day cumulative precipitation forecast, little rain is expected over the next week. There was a data gap in real-time flow at the USGS’s Point of Rocks gage yesterday, so yesterday’s daily average flow is estimated

Daily Potomac flow and demand update (Thursday, 2022-10-27)

Submitted by admin1 on Thu, 10/27/2022 - 12:46

According to Middle Atlantic River Forecast Center (MARFC) map products, there was 0.01 to 0.27 inches of rain in the basin over the past 24 hours. The LFFS average basin precipitation is 0.12 inches. MARFC predicts no rainfall over the next three days, although 0.25-0.75 inches of rain is expected in the 5 and 7-day forecasts.

Yesterday, WSSC Water temporarily provided all of the City of Rockville's water. WSSC Water is no longer serving them.

Daily Potomac flow and demand update (Tuesday, 2022-10-25)

Submitted by admin1 on Tue, 10/25/2022 - 09:00

According to Middle Atlantic River Forecast Center (MARFC) map products, there was no significant precipitation in the basin over the past 24 hours. The basin has been dry over the past three days, with the exception of the Monocacy sub-basin, which received up to ½ inch of rain. MARFC predicts accumulations of  trace amounts to ¼ inch over the next three days.

Initiation of CO-OP daily drought monitoring and reporting (Monday, 2022-10-24)

Submitted by admin1 on Mon, 10/24/2022 - 09:00

CO-OP is initiating daily drought monitoring and reporting today because Potomac River flow at the US Geological Survey’s gage at Point of Rocks, Maryland, has fallen below 2000 cubic feet per second (cfs), CO-OP's daily monitoring threshold. According to National Weather Service's (NWS) quantitative precipitation forecasts, less than a 1/10 of an inch of rain is expected in the basin over the next 3 days.

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.