In the last 24 hours, MARFC reports precipitation ranging from 0.01 to 0.25 inches in portions of the Potomac watershed above Little Falls. The forecast for the next three days indicates a potential accumulation of up to 0.25-inch precipitation. (Note this is a correction to the emailed version.)
Despite the river flows at Point of Rocks being above the daily monitoring threshold of 2000 cfs, they remain relatively low for this time of year. Until a significant increase occurs, the CO-OP will continue daily monitoring to closely observe the situation.
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 precipitation: 0 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.45 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.49 (inches)
Daily flows:
Little Falls gage flow 2023-06-13: 1222 MGD (1890 cfs)
Little Falls gage flow 2023-06-14: 1176 MGD (est., based on recently available real-time data) (1820 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-06-13: 1325 MGD (2050 cfs)
Point of Rocks flow 2023-06-14: 1351 MGD (est., based on recently available real-time data) (2090 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-06-13):
Fairfax Water Corbalis withdrawal (Potomac): 109 MGD
WSSC Water Potomac withdrawal: 144 MGD
Washington Aqueduct withdrawal: 144 MGD
Loudoun Water withdrawal: 14 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 410 MGD
Total net Potomac withdrawal: 404 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2050 cfs
QPR, obs: 2050 cfs
QPR, WS: 0 cfs
Note to Loudoun Water: See NWS ensemble flow forecasts (HEFS, GEFS, NAEFS) for Point of Rocks flow for the next 7 days – see https://www.weather.gov/erh/mmefs_marfc?id=PORM2&model=NAEFS.
Note: Potomac River flow at Point of Rocks has dropped below the low-flow threshold of 2,000 cfs. When this occurs, per the Water Supply Coordination Agreement of 1982, CO-OP begins daily monitoring and reporting of Potomac flows and withdrawals on behalf of the CO-OP suppliers, Fairfax Water, Washington Aqueduct, and WSSC Water. Suppliers can review data at CO-OP's Data Portal at www.icprbcoop.org. Reports formatted in approved templates should be submitted by email to coop@icprb.org by 8:00 am for automated processing. Published monitoring reports are at http://icprbcoop.org/products/monitoring-reports.