Situational Awareness (Monday, 2024-07-01)
CO-OP is suspending drought monitoring as flow at the US Geological Survey’s gage at Point of Rocks, Maryland, has exceeded the daily threshold of 2000 cfs. Predictions from the Middle Atlantic River Forecast Center indicate flows will stay above this threshold for at least the next 5 days. Approximately 0.8 inches of rain is forecasted in the basin over the next 7 days. We will continue to monitor conditions closely and we will resume daily drought monitoring if needed. Thank you for your continued support and cooperation.
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: 0.66 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.73 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 1.16 (inches)
Daily flows:
Little Falls gage flow 2024-06-30: 1105 MGD (1710 cfs)
Little Falls gage flow 2024-07-01: 1978 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 2024-06-30: 1739 MGD (2690 cfs)
Point of Rocks flow 2024-07-01: 1564 MGD (est., based on recently available real-time data) (2420 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2024-06-30: 1253 MGD (1939 cfs)
Note: Estimated flow below Great Falls intake is flow at Little Falls plus Little Falls water supply withdrawal.
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2024-06-30):
Fairfax Water Corbalis withdrawal - Potomac: 120 MGD
WSSC Water Potomac withdrawal: 130 MGD
Washington Aqueduct withdrawal - Great Falls: 0 MGD
Washington Aqueduct withdrawal - Little Falls: 148 MGD
Loudoun Water withdrawal: 13 MGD
Loudoun Water Broad Run discharge: 5 MGD
Total Potomac withdrawal: 412 MGD
Total net Potomac withdrawal: 407 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 2690 cfs
QPR, obs: 2690 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 – https://www.weather.gov/erh/mmefs_marfc?id=PORM2&model=NAEFS. See US Army Corps of Engineers Potomac River Basin page for observed releases from Savage and Jennings Randolph reservoirs - https://www.nab-wc.usace.army.mil/nab/poto.html; See US Army Corps of Engineers North Branch Potomac River and Savage River page for scheduled releases - https://www.nab-wc.usace.army.mil/nab/northBranch.html.
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.