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, 2026-01-26)

Submitted by hmoltz on Mon, 01/26/2026 - 13:20

Situational Awareness (Monday, 2026-01-26)
According to the Middle Atlantic River Forecast Center, 0.5-2.0 inches of liquid-equivalent precipitation fell in the basin over the past 24 hours. Up to 0.1 inches of additional precipitation is forecast in the far western portion of the basin over the next 3 days.  No precipitation is expected in the rest of the basin over that same 3-day period.

Special Conditions
None

Daily Potomac flow and demand update (Sunday, 2026-01-25)

Submitted by snummer on Sun, 01/25/2026 - 14:01

Situational Awareness (Sunday, 2026-01-25)
According to the Middle Atlantic River Forecast Center, the past 24 hours saw between 0.25 and 1 inch of precipitation. Over the next 3 days, the average basin liquid-equivalent precipitation may be around 1 inch, with the most upstream regions of the watershed seeing between 1.25 and 1.75 inches of precipitation.

Special Conditions
None

Daily Potomac flow and demand update (Saturday, 2026-01-24)

Submitted by admin1 on Sat, 01/24/2026 - 13:45

Situational Awareness (Saturday, 2026-01-24)
No precipitation fell in the Potomac basin yesterday. A cumulative average of 1 to 1 1/2 inches is expected in the portion of the watershed above Little Falls over the next 3 days according to information from the Mid-Atlantic River Forecast Center.

Special Conditions
None

Daily flows:
Little Falls gage flow 2026-01-23: 1364 MGD (2110 cfs)

Daily Potomac flow and demand update (Thursday, 2026-01-15)

Submitted by snummer on Thu, 01/15/2026 - 14:01

Situational Awareness (Thursday, 2026-01-15)
Over the past 24 hours trace amounts of rain fell in the northern portions of the basin, reaching up to approximately 0.25 inches in localized areas. The next 3 days may see up to 0.1 inches of rain across the basin, according to the Middle Atlantic River Forecast Center predictions. 

Special Conditions
None

Daily Potomac flow and demand update (Wednesday, 2026-01-14)

Submitted by admin1 on Wed, 01/14/2026 - 13:16

Situational Awareness (Wednesday, 2026-01-14):
According to the Middle Atlantic River Forecast Center, no precipitation was observed across the basin yesterday. The next weather system is expected to bring light rain transitioning to snow this evening into Thursday morning. Over the next three days, average basin precipitation is forecast to range from 0.01 to 0.25 inches, with slightly higher amounts possible in the North Branch over the five- to seven-day forecast period.

Special Conditions:
None