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 (Tuesday 09/23/2014)

Submitted by admin1 on Tue, 09/23/2014 - 09:00

Over the last 24 hours 0.1 to 0.75 inches of rain fell in the central portion of the basin, with the most falling along the border between Fairfax and Prince William counties. The National Weather Service indicates a chance of rain across the basin beginning Wednesday night through Thursday afternoon. Total rainfall amounts are predicted between 0.1 and 1.0 inch. The heaviest rainfall is forecast in the metro area and areas to the east.

Daily Potomac flow and demand update (Monday 09/22/2014)

Submitted by admin1 on Mon, 09/22/2014 - 09:00

Scattered rain, ranging from trace amounts to almost half an inch, occurred in localized portions of the basin over the last 24 hours according to the National Weather Service. The Middle Atlantic River Forecast Center predicts that less than 0.1 inch of rain may fall in a small area of the far western portion of the basin over the next 72 hours. No precipitation is expected across the rest of the basin during that period.

Daily Potomac flow and demand update (Sunday 09/21/2014)

Submitted by admin1 on Sun, 09/21/2014 - 09:00

Trace amounts of rain fell in a limited area between the USGS gage at Point of Rocks, MD and Washington, D.C. over the last 24 hours. The National Weather Service indicates there is a chance of 0.03 to 0.10 inches of rain over the next 72 hours and 0 to 0.5 inches over the next 7 days.

Thank you again to those sending in weekend daily withdrawal numbers.

Daily Potomac flow and demand update (Saturday 09/20/2014)

Submitted by admin1 on Sat, 09/20/2014 - 09:00

No rain fell in the basin over the last 24 hours. The National Weather Service indicates that there is a chance of trace rainfall over the next 72 hours and 0.1 to 0.5 inches distributed around the basin over the next 7 days.

Thank you to those sending in weekend daily withdrawal numbers. Please continue to send them to coop@icprb.org by 8 am on Sunday.

Daily Potomac flow and demand update (Friday 09/19/2014)

Submitted by admin1 on Fri, 09/19/2014 - 09:00

A negligible amount of rain fell in limited areas over the last 24 hours. The National Weather Service indicates there is a chance of trace rainfall over the next 72 hours and up to 0.1 inches total over the next 7 days across much of the basin.

We will continue daily monitoring over the weekend. If you are responsible for sending us daily withdrawals, please send them to coop@icprb.org by 8am on both Saturday and Sunday. Thank you!

Daily Potomac flow and demand update (Friday 10/11/2013)

Submitted by admin1 on Fri, 10/11/2013 - 09:00

Point of Rocks flow is at 4,820 cfs. Within the last 24 hours the Potomac basin has received between 0.1 and 5 inches of precipitation. Rain is expected to continue over the next 72 hours bringing new precipitation amounts between 0.25 and 2 inches.

With rain continuing to fall across much of the basin, and Point of Rocks flow being above the low flow monitoring threshold of 2,000 cfs, daily monitoring will be discontinued until further notice. Thank you to all for your contribution to the monitoring efforts.

Daily Potomac flow and demand update (Thursday 10/10/2013)

Submitted by admin1 on Thu, 10/10/2013 - 09:00

With rain continuing to fall across much of the basin, flow at the Point of Rocks gage is 1,910 cfs. Over the past 24 hours, rainfall in the basin has ranged from zero in the west to 1.5 inches in the southeast. The 72-hour forecast predicts between 0.5 and 2 inches of rain across the basin, increasing from west to east.

Daily Potomac flow and demand update (Tuesday 10/08/2013)

Submitted by admin1 on Tue, 10/08/2013 - 09:00

While the entire basin received significant rainfall yesterday, flow at the Point of Rocks gage has not yet risen much. MARFC predicts that flow will rise above 2,000 cfs sometime tomorrow. The highest rainfall amounts, between 1.25 and 1.75 inches, fell in the central part of the basin. The other areas received between 0.25 and 1.25 inches. The 72-hour forecast shows a chance of 0.25 and 1.50 inches of rain, with the amounts increasing in bands from west to east.