Monitoring Updates

Current drought monitoring status: Not Active

Drought monitoring was discontinued on October 11 after flow at the Point of Rocks gage rose well above the 2,000 cfs threshold.

Daily monitoring temporarily discontinued over the weekend October 5 & 6, 2013.

Daily monitoring temporarily discontinued over the weekend September 28 & 29, 2013.

Daily monitoring temporarily discontinued over the weekend September 21 & 22, 2013.

Daily monitoring commenced on September 17, 2013.

Potomac River flow at Point of Rocks has dropped below the low-flow threshold of 2,000 cfs. When this occurs, CO-OP begins conducting daily monitoring and reporting of Potomac flows and withdrawals.


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

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 Flows:

    Little Falls gage flow 10/10: 1400 MGD  (2170 cfs)

    Little Falls gage flow 10/11: 1610 MGD (est., based on recently available real time data)  (2489 cfs)

          Note: Gage flow at Little Falls is measured after water supply withdrawals.

    Point of Rocks flow 10/10: 1470 MGD (2270 cfs)

    Point of Rocks flow 10/11: 3120 MGD (est., based on recently available real time data) (4820 cfs)

Potomac Demand (10/10/13):

    FW Corbalis raw water withdrawal (Potomac): 84 MGD

    WSSC Potomac Withdrawal: 104 MGD

    Aqueduct withdrawal: 126 MGD

    Total Potomac withdrawals: 313 MGD


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

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 Flows:

        Little Falls gage flow 10/09: 1430 MGD  (2210 cfs)

        Little Falls gage flow 10/10: 1170 MGD (est., based on recently available real time data)  (1810 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/09: 1140 MGD (1770 cfs)

        Point of Rocks flow 10/10: 1230 MGD (est., based on recently available real time data) (1,910 cfs)

Potomac Demand (10/09/13):

        FW Corbalis raw water withdrawal (Potomac): 94 MGD

        WSSC Potomac Withdrawal: 117 MGD

        Aqueduct withdrawal: 127 MGD

        Total Potomac withdrawals: 338 MGD


Daily Potomac flow and demand update (Wednesday 10/09/2013)

Flows in basin streams have risen modestly due to Monday's rain event, but flow at Point of Rocks remains below 2000 cfs. National Weather Service forecasts call for more rain over the next 72 hours, though the highest accumulations are expected to be in the eastern portion of the basin.

Daily Flows:

        Little Falls gage flow 10/08: 1780 MGD  (2750 cfs)

        Little Falls gage flow 10/09: 1490 MGD (est., based on recently available real time data)  (2300 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/08: 1050 MGD (1620 cfs)

        Point of Rocks flow 10/09: 1110 MGD (est., based on recently available real time data) (1720 cfs)

Potomac Demand (10/08/13):

        FW Corbalis raw water withdrawal (Potomac): 71 MGD

        WSSC Potomac Withdrawal: 109 MGD

        Aqueduct withdrawal: 139 MGD

        Total Potomac withdrawals: 319 MGD


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

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 between 0.25 and 1.50 inches of rain, with the amounts increasing in bands from west to east.

Daily Flows:

        Little Falls gage flow 10/07: 1120 MGD  (1730 cfs)

        Little Falls gage flow 10/08: 1980 MGD (est., based on recently available real time data)  (3060 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/07: 980 MGD (1520 cfs)

        Point of Rocks flow 10/08: 980 MGD (est., based on recently available real time data) (1520 cfs)

Potomac Demand (10/07/13):

        FW Corbalis raw water withdrawal (Potomac): 109 MGD

        WSSC Potomac Withdrawal: 123 MGD

        Aqueduct withdrawal: 141 MGD

        Total Potomac withdrawals: 373 MGD



Daily Potomac flow and demand update (Monday 10/07/2013)

Flow at the Point of Rocks gage dropped approximately 400 cfs over the weekend. The western portion of the basin received between trace amounts and 0.5 inches of rain over the last 24 hours. The 72-hour forecast shows a chance of 0.5 to 1.25 inches of rain across the basin. The NOAA/MARFC briefing from Sunday, October 6, indicates that this rain is from a cold front crossing the region, not from Tropical Depression Karen. The heaviest rain is expected east of the I-95 corridor.

Daily Flows:

        Little Falls gage flow 10/06: 1070 MGD  (1650 cfs)

        Little Falls gage flow 10/07: 890 MGD (est., based on recently available real time data)  (1370 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/06: 950 MGD (1470 cfs)

        Point of Rocks flow 10/07: 920 MGD (est., based on recently available real time data) (1420 cfs)

Potomac Demand (10/06/13):

        FW Corbalis raw water withdrawal (Potomac): 108 MGD

        WSSC Potomac Withdrawal: 141 MGD

        Aqueduct withdrawal: 138 MGD

        Total Potomac withdrawals: 387 MGD


Daily Potomac flow and demand update (Friday 10/04/2013)

Potomac River flows at Point of Rocks and Little Falls are still slightly higher due to last weekend's water quality releases from the North Branch reservoirs. The basin is expected to receive some precipitation - trace amounts up to a half inch - on Sunday. The Middle Atlantic River Forecast Center predicts that flow at Point of Rocks will fall to 1720 cfs over the next 72 hours.

Because flow conditions are expected to be relatively stable over the next 72 hours, CO-OP's daily drought monitoring and reporting will be suspended over the weekend, and will resume on Monday.

Daily Flows:

        Little Falls gage flow 10/03: 1030 MGD  (1590 cfs)

        Little Falls gage flow 10/04: 1060 MGD (est., based on recently available real time data)  (1640 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/03: 1490 MGD (2300 cfs)

        Point of Rocks flow 10/04: 1420 MGD (est., based on recently available real time data) (2190 cfs)

Net Potomac Production (10/03/13):

        FW Corbalis raw water withdrawal (Potomac): 107 MGD

        WSSC Potomac Production: 119 MGD

        Aqueduct withdrawal: 154 MGD

        Total Potomac demand: 380 MGD


Daily Potomac flow and demand update (Thursday 10/03/2013)

No rain fell in the basin over the last 24 hours and none is predicted for the next 72-hour period. The rise in flow at Point of Rocks is due to the release this weekend from the North Branch Reservoirs.

Daily Flows:

        Little Falls gage flow 10/02: 1020 MGD  (1580 cfs)

        Little Falls gage flow 10/03: 960 MGD (est., based on recently available real time data)  (1480 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/02: 1210 MGD (1870 cfs)

        Point of Rocks flow 10/03: 1330 MGD (est., based on recently available real time data) (2050 cfs)

Net Potomac Production (10/02/13):

        FW Corbalis raw water withdrawal (Potomac): 109 MGD

        WSSC Potomac Production: 126 MGD

        Aqueduct withdrawal: 147 MGD

        Total Potomac demand: 382 MGD


Daily Potomac flow and demand update (Wednesday 10/02/2013)

According to the National Weather Service, there was 0 to 0.25 inches of rain in the basin over the last 24 hours. A tenth of an inch of rain in the North Branch is predicted for the next 72 hours.

Daily Flows:

        Little Falls gage flow 10/01: 1050 MGD  (1620 cfs)

        Little Falls gage flow 10/02: 1030 MGD (est., based on recently available real time data)  (1600 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 10/01: 1110 MGD (1710 cfs)

        Point of Rocks flow 10/02: 1180 MGD (est., based on recently available real time data) (1820 cfs)

Net Potomac Production (10/01/13):

        FW Corbalis raw water withdrawal (Potomac): 108 MGD

        WSSC Potomac Production: 130 MGD

        Aqueduct withdrawal: 143 MGD

        Total Potomac demand: 381 MGD


Daily Potomac flow and demand update (Tuesday 10/01/2013)

According to the National Weather Service, there was no rain in the basin over the last 24 hours. No rain is predicted for the next 72 hours.

Daily Flows:

        Little Falls gage flow 09/30: 1110 MGD  (1710 cfs)

        Little Falls gage flow 10/01: 1010 MGD (est., based on recently available real time data)  (1560 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/30: 1170 MGD (1810 cfs)

        Point of Rocks flow 10/01: 1090 MGD (est., based on recently available real time data) (1680 cfs)

Net Potomac Production (09/30/13):

        FW Corbalis raw water withdrawal (Potomac): 116 MGD

        WSSC Potomac Production: 134 MGD

        Aqueduct withdrawal: 143 MGD

        Total Potomac demand: 393 MGD


Daily Potomac flow and demand update (Monday 09/30/2013)

Point of Rocks flow fell below 2,000 cfs over the weekend and therefore we are continuing daily monitoring. No rain fell in the basin over the last 24 hours and no rain is predicted for the next 72 hours.

Daily Flows:

    Little Falls gage flow 09/29: 1190 MGD  (1840 cfs)

    Little Falls gage flow 09/30: 1110 MGD (est., based on recently available real time data)  (1720 cfs)

          Note: Gage flow at Little Falls is measured after water supply withdrawals.

    Point of Rocks flow 09/29: 1230 MGD (1900 cfs)

    Point of Rocks flow 09/30: 1180 MGD (est., based on recently available real time data) (1820 cfs)

Net Potomac Production (09/29/13):

    FW Corbalis raw water withdrawal (Potomac): 95 MGD

    WSSC Potomac Production: 129 MGD

    Aqueduct withdrawal: 133 MGD

    Total Potomac demand: 358 MGD


Daily Potomac flow and demand update (Friday 09/27/2013)

Daily monitoring reports will be suspended over the weekend since flow at Point of Rocks is above the monitoring threshold of 2000 cfs.  A decision on whether or not to resume daily monitoring will be made on Monday based on flow and weather conditions.

The National Weather Service reports that trace amounts of precipitation fell in the basin over the past 24 hours and no precipitation is forecast for the next 72 hours. USGS staff informed CO-OP that recently reported flows at Point of Rocks had been influenced by changing backwater conditions resulting from the die-off of aquatic grasses.  The USGS has revised its rating curve for Point of Rocks based on measurements taken yesterday.

Daily Flows:

        Little Falls gage flow 09/26: 1280 MGD  (1980 cfs)

        Little Falls gage flow 09/27: 1280 MGD (est., based on recently available real time data)  (1980 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/26: 1430 MGD (2210 cfs)

        Point of Rocks flow 09/27: 1420 MGD (est., based on recently available real time data) (2190 cfs)

Net Potomac Production (09/26/13):

        FW Corbalis raw water withdrawal (Potomac): 97 MGD

        WSSC Potomac Production: 131 MGD

        Aqueduct withdrawal: 147 MGD

        Total Potomac demand: 375 MGD


Daily Potomac flow and demand update (Thursday 09/26/2013)

Trace amounts to half an inch of rain fell in the central part of the basin over the last 24 hours. No rain is predicted for the next 72 hours.

Daily Flows:

        Little Falls gage flow 09/25: 1290 MGD  (2000 cfs)

        Little Falls gage flow 09/26: 1280 MGD (est., based on recently available real time data)  (1980 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/25: 1200 MGD (1850 cfs)

        Point of Rocks flow 09/26: 1160 MGD (est., based on recently available real time data) (1800 cfs)

Net Potomac Production (09/25/13):

        FW Corbalis raw water withdrawal (Potomac): 102 MGD

        WSSC Potomac Production: 124 MGD

        Aqueduct withdrawal: 137 MGD

        Total Potomac demand: 363 MGD


Daily Potomac flow and demand update (Wednesday 09/25/2013)

No precipitation fell in the basin yesterday and there is no rainfall predicted over the next three days.

Daily Flows:

        Little Falls gage flow 09/24: 1290 MGD  (1990 cfs)

        Little Falls gage flow 09/25: 1250 MGD (est., based on recently available real time data)  (1940 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/24: 1220 MGD (1880 cfs)

        Point of Rocks flow 09/25: 1200 MGD (est., based on recently available real time data) (1860 cfs)

Net Potomac Production (09/24/13):

        FW Corbalis raw water withdrawal (Potomac): 90 MGD

        WSSC Potomac Production: 108 MGD

        Aqueduct withdrawal: 137 MGD

        Total Potomac demand: 335 MGD


Daily Potomac flow and demand update (Tuesday 09/24/2013)

Point of Rocks flow is 1820 cfs. No significant precipitation fell in the basin yesterday. Over the next 72-hours, the National Weather Service predicts no rainfall throughout the basin.

Daily Flows:

        Little Falls gage flow 09/23: 1312 MGD  (2030 cfs)

        Little Falls gage flow 09/24: 1280 MGD (est., based on recently available real time data)  (1980 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/23: 1234 MGD (1910 cfs)

        Point of Rocks flow 09/24: 1176 MGD (est., based on recently available real time data) (1820 cfs)

Net Potomac Production (09/23/13):

        FW Corbalis raw water withdrawal (Potomac): 96 MGD

        WSSC Potomac Production: 112 MGD

        Aqueduct withdrawal: 145 MGD

        Total Potomac demand: 353 MGD


​Daily Potomac flow and demand update (Monday 09/23/2013)

​Point of Rocks flow ​is 1890 cfs. Over the past 24-hours, the basin received 0.1 to 0.25 inches of precipitation. Over the next 72-hours, the National Weather Service predicts zero inches of precipitation.

Daily Flows:

        Little Falls gage flow 09/22: 1550 MGD  (2400 cfs)

        Little Falls gage flow 09/23: 1340 MGD (est., based on recently available real time data)  (2079 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/22: 1150 MGD (1780 cfs)

        Point of Rocks flow 09/23: 1220 MGD (est., based on recently available real time data) (1890 cfs)

Net Potomac Production (09/22/13):

        FW Corbalis raw water withdrawal (Potomac): 86 MGD

        WSSC Potomac Production: 116 MGD

        Aqueduct withdrawal: 128 MGD

        Total Potomac demand: 330 MGD


Daily Potomac flow and demand update (Friday 09/20/2013)

No significant precipitation fell in the basin yesterday. Over the next 72-hours, the National Weather Service predicts 1 to 2.25 inches of rain throughout the basin with heaviest rain expected around central Maryland.

Due to the expected rain over the weekend, we are temporarily discontinuing daily monitoring on Saturday and Sunday and will resume on Monday.

Daily Flows:

        Little Falls gage flow 09/19: 1170 MGD  (1810 cfs)

        Little Falls gage flow 09/20: 1140 MGD (est., based on recently available real time data)  (1770 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/19: 1150 MGD (1780 cfs)

        Point of Rocks flow 09/20: 1180 MGD (est., based on recently available real time data) (1820 cfs)

Net Potomac Production (09/19/13):

        FW Corbalis raw water withdrawal (Potomac): 104 MGD

        WSSC Potomac Production: 120 MGD

        Aqueduct withdrawal: 144 MGD

        Total Potomac demand: 368 MGD


Daily Potomac flow and demand update (Thursday 09/19/2013)

Measured flows at Point of Rocks continue to decrease as of this morning.  According to USGS, the grasses around the Point of Rocks gage are starting to die off, resulting in less backwater.  USGS plans to conduct on-site measurements bi-weekly while low flow conditions persist.

No precipitation fell in the basin yesterday. Over the next 72-hours, the National Weather Service predicts 0.5 to 1.25 inches of rainfall throughout the basin with most areas expecting approximately 0.75 inches.

Daily Flows:

        Little Falls gage flow 09/18: 1200 MGD  (1860 cfs)

        Little Falls gage flow 09/19: 1170 MGD (est., based on recently available real time data)  (1810 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/18: 1230 MGD (1900 cfs)

        Point of Rocks flow 09/19: 1160 MGD (est., based on recently available real time data) (1800 cfs)

Net Potomac Production (09/18/13):

        FW Corbalis raw water withdrawal (Potomac): 105 MGD

        WSSC Potomac Production: 126 MGD

        Aqueduct withdrawal: 149 MGD

        Total Potomac demand: 380 MGD


Daily Potomac flow and demand update (Wednesday 09/18/2013)

No significant precipitation fell in the basin yesterday. Over the next 72-hours, the National Weather Service predicts a chance of up to a quarter inch of rain in the southwestern portion of the basin.

Daily Flows:

        Little Falls gage flow 09/17: 1200 MGD  (1860 cfs)

        Little Falls gage flow 09/18: 1220 MGD (est., based on recently available real time data)  (1890 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/17: 1310 MGD (2020 cfs)

        Point of Rocks flow 09/18: 1190 MGD (est., based on recently available real time data) (1840 cfs)

Net Potomac Production (09/17/13):

        FW Corbalis raw water withdrawal (Potomac): 92 MGD

        WSSC Potomac Production: 112 MGD

        Aqueduct withdrawal: 151 MGD

        Total Potomac demand: 355 MGD


Daily Potomac flow and demand update (Tuesday 09/17/2013)

Flow at Point of Rocks is currently 1,980 cfs, which is below the low-flow monitoring threshold of 2,000 cfs. The rating curve at Point of Rocks was changed yesterday by the USGS to more accurately reflect flow conditions, increasing reported flow from 1,760 cfs to over 2,000 cfs earlier this morning. Because Point of Rocks flow is continuing to drop we have decided to commence daily monitoring.

Yesterday the basin received  0.1-0.25 inches of rainfall (some areas received as much as 0.5 inches).

Over the next 72 hours the quantitative precipitation forecast calls for 0.1-0.25 inches of rainfall in the North Branch of the Potomac basin only.

Thank you to those who provided us with recent demand data and for your continued cooperation over the next couple of days.

Daily Flows:

        Little Falls gage flow 09/16: 1220 MGD  (1880 cfs)

        Little Falls gage flow 09/17: 1170 MGD (est., based on recently available real time data)  (1810 cfs)

              Note: Gage flow at Little Falls is measured after water supply withdrawals.

        Point of Rocks flow 09/16: 1370 MGD (2120 cfs)

        Point of Rocks flow 09/17: 1280 MGD (est., based on recently available real time data) (1980 cfs)

Net Potomac Production (09/16/13):

        FW Corbalis raw water withdrawal (Potomac): 98 MGD (estimated from 9/15/2013)

        WSSC Potomac Production: 122 MGD

        Aqueduct withdrawal: 150 MGD

        Total Potomac demand: 370 MGD