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 2019-10-15)

Submitted by admin1 on Tue, 10/15/2019 - 09:00

According to the Middle Atlantic River Forecasting Center, no rain fell in the basin over the past 24 hours. Between 0.25 and 1 inch of rain is expected over the next 3 days.

Although flows at the USGS gage at Point of Rocks are currently above 2000 cfs, the trigger for daily monitoring, daily monitoring will be continued at this time.

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 2019-10-14)

Submitted by admin1 on Mon, 10/14/2019 - 09:00

No significant amount of rain has fallen in the Potomac basin over the past 3 days. According to Middle Atlantic River Forecast Center estimates, 1/4 to 3/4 inches is expected throughout the basin on Wednesday. Flow in the Potomac River at Point of Rocks is still elevated from last week's rainfall, and is above CO-OP's threshold for drought monitoring. We will reassess the need for daily monitoring after Wednesday's rainfall.

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

Daily Potomac flow and demand update (Sunday 2019-10-13)

Submitted by admin1 on Sun, 10/13/2019 - 09:00

Trace amounts of precipitation occurred around the outer perimeter of the basin, resulting in an average basin precipitation of 0.016 inches for yesterday. According to MARFC, the basin precipitation for the month of October is currently at 1 inch, which is about normal for this time of the month. Above the USGS gage at Point of Rocks, this precipitation has returned some of the precipitation totals to near normal or above normal for the month. However, below this USGS gage, greater than 75% below normal precipitation totals for the month remain throughout the basin.

Daily Potomac flow and demand update (Saturday 2019-10-12)

Submitted by admin1 on Sat, 10/12/2019 - 09:00

Dry conditions continue, and little rain is in the forecast over the next 7 days.

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)

Yesterday's area-weighted average basin precip: 0 (inches)
Past 3-day cumulative area-weighted average basin precip: 0.04531 (inches)
Past 7-day cumulative area-weighted average basin precip: 1.08125 (inches)

Daily Potomac flow and demand update (Friday 2019-10-11)

Submitted by admin1 on Fri, 10/11/2019 - 09:00

According to the Middle Atlantic River Forecast Center, no rain fell in the basin over the past 24 hours. Between 0.1 and 0.75 inches of rain is expected over the next 7 days.

Although flows at the USGS gage at Point of Rocks are currently above 2000 cfs, the trigger for daily monitoring, daily monitoring will be continued at this time due to limited rain in the forecast.

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

Daily Potomac flow and demand update (Thursday 2019-10-10)

Submitted by admin1 on Thu, 10/10/2019 - 09:00

Potomac River flow at Point of Rocks has increased to a level above 2000 cfs, CO-OP's threshold for daily drought monitoring and reporting. However, little rain is on the horizon and streamflow forecasts indicate that flow will fall back below 2000 cfs within a few days, so we will not discontinue daily drought operations at this time. The Middle Atlantic River Forecast Center predicts up to 1/10 inches of rain in the western portion of the Potomac basin over the next 3 days. Over the next 7 days, accumulations of 1/10 to 1/2 inches are expected in the basin.

Daily Potomac flow and demand update (Wednesday 2019-10-09)

Submitted by admin1 on Wed, 10/09/2019 - 09:00

According to Middle Atlantic River Forecast Center estimates, 0 to 0.50 inches of rain fell in the basin in the past 24 hours. The CO-OP's Low Flow Forecast System reports that this precipitation amounts to a basin-wide average of 0.37 inches for yesterday. Between 0.10 and 0.50 inches of rain is forecast over the next 7 days.

The USGS gage at Point of Rocks is currently above 2000 cfs, our trigger for daily monitoring. We will continue daily monitoring efforts until we see that flows have significantly improved for several days.

Daily Potomac flow and demand update (Tuesday 2019-10-08)

Submitted by admin1 on Tue, 10/08/2019 - 09:00

According to Middle Atlantic River Forecast Center estimates, 0 to 1.50 inches of rain fell in the basin in the past 24 hours. The CO-OP's Low Flow Forecast System reports that this precipitation amounts to a basin-wide average of 0.55271 inches for yesterday. Between 0 and 0.25 inches of rain is forecast over the next 7 days.

The USGS gage at Point of Rocks temporarily rose above 2000 cfs due to the recent precipitation. However, flows have already begun to drop below 2000 cfs.

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

Daily Potomac flow and demand update (Monday 2019-10-07)

Submitted by admin1 on Mon, 10/07/2019 - 09:00

Modest relief from the dry conditions may be on the way - the Middle Atlantic River Forecast Center predicts accumulations of 0.1 to 1.0 inches of rain in the basin over the next 24 hours.

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 (Sunday 2019-10-06)

Submitted by admin1 on Sun, 10/06/2019 - 09:00

According to MARFC's forecasted precipitation, the next 7 days is expected to bring between 0.25 and 1 inch of rain to 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)

Yesterday's area-weighted average basin precip: 0 (inches)
Past 3-day cumulative area-weighted average basin precip: 0.04 (inches)
Past 7-day cumulative area-weighted average basin precip: 0.43 (inches)