Situational Awareness (Saturday, 2023-10-14)
Potomac River flow at the USGS’s Point of Rocks gage continues to fall. We expect some improvement in flows in the coming week because forecasts call for over a half inch of rain in the basin this weekend.
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 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 0.48 (inches)
Daily flows:
Little Falls gage flow 2023-10-13: 853 MGD (1320 cfs)
Little Falls gage flow 2023-10-14: 827 MGD (est., based on recently available real-time data) (1280 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-10-13: 911 MGD (1410 cfs)
Point of Rocks flow 2023-10-14: 892 MGD (est., based on recently available real-time data) (1380 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-10-13):
Fairfax Water Corbalis withdrawal - Potomac: 89 MGD
WSSC Water Potomac withdrawal: 141 MGD
Washington Aqueduct withdrawal - Great Falls: 79 MGD
Washington Aqueduct withdrawal - Little Falls: 77 MGD
Loudoun Water withdrawal: 9 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 396 MGD
Total net Potomac withdrawal: 390 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1410 cfs
QPR, obs: 1410 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.