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, 2022-11-07)

Submitted by admin1 on Mon, 11/07/2022 - 12:42

According to MARFC and CO-OP's Low Flow Forecast System, precipitation totals between 0 and 0.28 inches occurred yesterday. The next 72-hour forecast predicts a precipitation total of up to 0.1 inches for basin locations above the USGS gage at Point of Rocks. Longer-range forecasts (5- and 7-days) indicate heavier rain with accumulations of about an inch in the North Branch area of the basin.

Daily Potomac flow and demand update (Sunday, 2022-11-06)

Submitted by admin1 on Sun, 11/06/2022 - 13:46

Light rain is forecast in the Potomac basin over the next three days, with accumulations of up to 0.25 inches predicted for some areas. Longer range forecasts indicate heavier rain – with accumulations of about an inch - 6 and 7 days in the future. 

Recent basin-wide average precipitation (above Little Falls):
(based on CO-OP's Low Flow Forecast System analysis of Middle Atlantic River Forecast Center (MARFC) gridded multisensor precipitation estimates)

Daily Potomac flow and demand update (Tuesday, 2022-11-01)

Submitted by admin1 on Tue, 11/01/2022 - 13:08

Most parts of the Potomac basin above Little Falls received 1/10 to ½ inch of rain yesterday. River flows are already responding. However, the forecast is for dry conditions over the next 7 days, so we expect this slight increase in flows to be short-lived.

Daily flows:
Little Falls gage flow 2022-10-31: 1196 MGD (1850 cfs)
Little Falls gage flow 2022-11-01: 1209 MGD (est., based on recently available real-time data) (1870 cfs)

Daily Potomac flow and demand update (Monday, 2022-10-31)

Submitted by admin1 on Mon, 10/31/2022 - 12:10

Over the past day, 0 to 0.1 inches of precipitation occurred in the Potomac basin above Little Falls; the majority occurred in the North Branch. According to the MARFC’s 72-hour forecast, total rainfall in the basin will range from 0.01 to 0.5 inches over the next three days, with more rain occurring in the southeastern portions (including the DC area) than in the northwestern parts.

Daily Potomac flow and demand update (Sunday, 2022-10-30)

Submitted by admin1 on Sun, 10/30/2022 - 11:56

Daily Potomac flow and demand update (Sunday, 2022-10-30)
Over the past day, no significant rainfall occurred in the Potomac basin above Little Falls. According to the MARFC’s 72-hour forecast, total precipitation in the basin will range from 0.01 to 0.25 inches over the next three days, with more rain occurring in the southeastern portions (including the DC area) than in the northwestern portions.

Daily Potomac flow and demand update (Saturday, 2022-10-29)

Submitted by admin1 on Sat, 10/29/2022 - 12:35

No significant rainfall occurred in the Potomac basin above Little Falls over the past day. According to the MARFC’s 72-hour forecast, total precipitation in the basin will range from 0.01 to 0.25 inches over the next three days, with more rain occurring in the southeastern portions of the basin (including the DC area) than in the northwestern portions.

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