Welcome to Day 2 of the 2022 WMA Drought Exercise. Simulated Potomac River flows are continuing to fall. We have asked WSSC Water to make a simulated reduction of their Potomac River withdrawals by 7 MGD to help maintain the Little Falls flow-by today. In addition, we have requested a simulated 141-MGD Little Seneca Reservoir release to help maintain the flow-by tomorrow. We estimate that 40 cfs of flow at Point of Rocks yesterday is due to a simulated past water supply release from Jennings Randolph Reservoir as noted in the simulated Loudoun Water drought operations protocol below.
ACTUAL 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: 0.65 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.66 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 2.71 (inches)
ACTUAL Daily flows:
Little Falls gage flow 2022-11-15: 9242 MGD (14300 cfs)
Little Falls gage flow 2022-11-16: 9372 MGD (est., based on recently available real-time data) (14500 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2022-11-15: 8014 MGD (12400 cfs)
Point of Rocks flow 2022-11-16: 6657 MGD (est., based on recently available real-time data) (10300 cfs)
ACTUAL Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2022-11-15):
Fairfax Water Corbalis withdrawal (Potomac): 73 MGD
WSSC Water Potomac withdrawal: 119 MGD
Washington Aqueduct withdrawal: 113 MGD
Loudoun Water withdrawal: 0 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 305 MGD
Total net Potomac withdrawal: 298 MGD
ACTUAL Yesterday's Patuxent, Occoquan, and Net Total System Withdrawal (2022-11-15):
FW Occoquan withdrawal:58 MGD
WSSC Patuxent withdrawal:39 MGD
ACTUAL Yesterday's total system withdrawal (2022-11-15): 403 MGD
ACTUAL Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 12400 cfs
QPR, obs: 12400 cfs
QPR, WS: 0 cfs
ACTUAL Today's estimated production* (2022-11-16):
FW estimated production:126 MGD
WSSC estimated production:147 MGD
Washington Aqueduct estimated production:119 MGD
Total estimated production:392 MGD
LW total estimated consumption:21 MGD**
*Based on CO-OP daily demand forecasting models. FW includes the LW purchase and excludes Falls Church. Washington Aqueduct includes Falls Church
**LW total estimated consumption includes purchase and production water and is not included in the total production estimate.
ACTUAL Tomorrow's estimated production* (2022-11-17):
FW estimated production:122 MGD
WSSC estimated production:147 MGD
Washington Aqueduct estimated production:121 MGD
Total estimated production:390 MGD
LW Total estimated consumption:21 MGD**
*Based on CO-OP daily demand forecasting models. FW includes the LW purchase and excludes Falls Church. Washington Aqueduct includes Falls Church
**LW total estimated consumption includes purchase and production water and is not included in the total production estimate.
SIMULATED Recommended operations for today (Day 2, A.M.):
SIMULATED Fairfax Water: Per operational preference, keep Potomac withdrawals steady. Maintain Griffith WTP at maximum production of 70 MGD.
SIMULATED WSSC Water: Reduce Potomac River withdrawal by 7 MGD and hold steady.
SIMULATED Seneca (release date, time, amount in MGD): Increase release from Little Seneca Reservoir to 141 MGD for Day 2 of Drought Exercise.
SIMULATED Washington Aqueduct: Meet all demands from Little Falls in order to maintain the Great Falls flow-by.
SIMULATED North Branch Reservoirs A.M. Summary: No North Branch releases for Day 2 of Drought Exercise.
SIMULATED Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 708 cfs
QPR, obs: 748 cfs
QPR, WS: 40 cfs
SIMULATED Reservoirs - Usable storage (Day 2, A.M., BG):
Facility, %Full, Current, Capacity*
WSSC’s Patuxent reservoirs, 61%, 6.26, 10.2
Fairfax Water’s Occoquan reservoir, 69%, 5.58, 8.05
Little Seneca Reservoir, 56%, 2.19, 3.9
Jennings Randolph Total Reservoir, 64%, 18.80, 29.4
Jennings Randolph water supply**, 59%, 7.7, 13.1
Jennings Randolph water quality**, 68%, 11.1, 16.3
Savage Reservoir, 33%, 2.1, 6.3
*Storage and capacities for Occoquan, Patuxent and Little Seneca reservoirs are provided by Washington metropolitan area water utilities, and based on best available information. Storage and capacities for Jennings Randolph and Savage reservoirs are based on observed water levels and available US ACE water level/storage tables from 1998. ICPRB estimates that sedimentation has resulted in a loss of total available storage in Jennings Randolph Reservoir of 1.6 BG in recent years, and this loss is not reflected in the numbers above.
** ICPRB's initial estimate. Final accounting of Jennings Randolph water supply versus water quality storage will be provided at a later date by the US ACE.
Note: Flow levels have dropped to a level that has triggered enhanced monitoring, per the drought operations manual of the Water Supply Coordination Agreement. When adjusted flow at Little Falls (adjusted flow is gage flow plus upstream withdrawals) less the environmental flow is less than twice the Washington metropolitan area withdrawals, the water suppliers will begin reporting yesterday's and today's withdrawals and this morning's reservoir storage volumes. ICPRB asks that communications be sent by 7:30 am and updates sent by 1:00 pm. Reporting can be submitted through www.icprbcoop.org, by email to coop@icprb.org, or by telephone by leaving a message with the CO-OP operations number at 301-274-8132. Monitoring emails can be viewed at http://icprbcoop.org/products/monitoring-reports. Thank you for your contribution to the monitoring efforts.
Best regards,
ICPRB CO-OP Drought Ops Team
coop@icprb.org