This is the third and last day of our 2020 Washington metropolitan area (WMA) annual drought exercise. Reported below are actual recent conditions and simulated drought operations.
Today we requested a simulated Little Seneca release of 22 MGD. This was based on the drought scenario and not yesterday’s actual release. We will provide analysis on the travel time of this test release in our report. You can follow the release at the USGS gage 01645000 SENECA CREEK AT DAWSONVILLE, MD here.
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RECENT CONDITIONS – 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 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.19 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 1.73 (inches)
Potomac River Flows:
Little Falls gage flow 2020-11-17: 6722 MGD (10400 cfs)
Little Falls gage flow 2020-11-18: 5823 MGD (est., based on recently available real time data) (9010 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2020-11-17: 5552 MGD (8590 cfs)
Point of Rocks flow 2020-11-18: 4770 MGD (est., based on recently available real time data) (7380 cfs)
Yesterday's Net Potomac withdrawal (2020-11-17):
FW Corbalis withdrawal (Potomac): 76 MGD
WSSC Potomac withdrawal: 94 MGD
Aqueduct withdrawal: 113 MGD
Loudoun withdrawal: 6 MGD
Total Potomac withdrawal: 288 MGD
Yesterday's Patuxent, Occoquan, and Net Total System Withdrawal (2020-11-17):
FW Occoquan withdrawal: 58 MGD
WSSC Water Patuxent withdrawal: 66 MGD
Yesterday's total system withdrawal (2020-11-17): 407 MGD
Loudoun Water Broad Run discharge:
Yesterday's (2020-11-17): 7 MGD
Today's estimated production* (2020-11-18):
FW estimated production: 150 MGD
WSSC Water estimated production: 146 MGD
Washington Aqueduct estimated production: 114 MGD
Total estimated production: 410 MGD
*Based on CO-OP daily demand forecasting models. FW includes the LW purchase and excludes Falls Church. Washington Aqueduct includes Falls Church
Tomorrow's estimated production* (2020-11-19):
FW estimated production:153 MGD
WSSC estimated production:146 MGD
Washington Aqueduct estimated production:116 MGD
Total estimated production:415 MGD
*Based on CO-OP daily demand forecasting models. FW includes the LW purchase and excludes Falls Church. Washington Aqueduct includes Falls Church
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Recommended (SIMULATED) operations for this morning (2020-11-18 A.M.):
Fairfax Water:
Maintain the (SIMULATED) load shift of 24 MGD off the Corbalis plant (Potomac) and onto the Griffith plant (Occoquan). Keep Potomac withdrawal rate as steady as possible.
WSSC Water:
Keep Potomac withdrawal rate (SIMULATED) as steady as possible.
Little Seneca (release date, time, amount in MGD):
A 22 MGD (SIMULATED) water supply release from Little Seneca Reservoir was requested at 8:28 AM.
Washington Aqueduct:
Maintain (SIMULATED) withdrawals at Little Falls at 150 MGD. Great Falls per operational preference.
Loudoun Water:
The following values (SIMULATED) are provided under the protocol developed to satisfy the Virginia Water Protection permit # 10-2020, Part I. 2. f (p. 10), and Part I.J.10
QPR, obs = 473 MGD (732 cfs) (SIMULATED)
QPR, WS = 50 MGD (SIMULATED)
QPR = 423 MGD (SIMULATED)
North Branch Reservoirs A.M. Summary:
A (SIMULATED) water supply release with a Luke target of 152 cfs is requested. This is equivalent to 98 MGD.
Reservoirs - Usable storage (2020-11-18 A.M., BG):
Facility, %Full, Current, Capacity*
WSSC’s Patuxent reservoirs, 81%, 8.23, 10.2
Fairfax Water’s Occoquan reservoir, 100%, 8.05, 8.05
Little Seneca Reservoir, 96%, 3.74, 3.9
Jennings Randolph Total Reservoir, 79%, 23.2, 29.4
Jennings Randolph water supply**, 100%, 13.1, 13.1
Jennings Randolph water quality**, 62%, 10.1, 16.3
Savage Reservoir, 65%, 4.1, 6.3
*Storage and capacities for Occoquan, Patuxent, and Little Seneca reservoirs are provided by Washington metropolitan area water utilities and based on the 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. The final accounting of Jennings Randolph's water supply versus water quality storage will be provided later by the US ACE.