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 (Wednesday, 2022-11-09)

Submitted by admin1 on Wed, 11/09/2022 - 13:58

Potomac River flow has remained relatively steady over the past week. According to National Weather Service forecasts, we can expect about 2 inches of rain during the next three days, mainly on Friday, as the remnants of tropical storm Nicole pass over the basin.

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, 2022-11-08)

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

There was no precipitation in the Potomac basin yesterday and none is forecast for the next three days. However, it looks like relief is on the way - there is a good chance of heavy rain late this week from subtropical storm Nicole.

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 (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)