Monitoring Reports

No additional operational changes are requested for this afternoon. SIMULATED flows at Little Falls are staying above 150 MGD. 

During yesterday’s practice call, the DCTC recommended entering the SIMULATED Drought Warning Stage of the MWCOG Drought Awareness Response Plan. This discussion occurred because the SIMULATED combined water supply storage in Jennings Randolph and Little Seneca fell below 60%.

Best regards, 
ICPRB CO-OP Drought Team

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. 

Following this morning's operations request by ICPRB CO-OP, WSSC Water initiated a SIMULATED water supply release from the Little Seneca Reservoir at 9:30 AM. This reservoir is located in the Black Hill Regional Park. 

In talking with Fairfax Water distribution staff this morning, we learned that the maximum possible SIMULATED load shift today from the Potomac to the Occoquan is 5 MGD due to ACTUAL installation work at the Griffith plant. 

Welcome to the first day of the 2022 WMA Drought Exercise. The simulation day is Thursday, August 25, 2022, and the basin conditions have reached the threshold of the "Warning" stage of the MWCOG drought regional plan. An actual practice Drought Coordination Technical Committee (DCTC) MS Teams meeting is scheduled for today (Tuesday, November 15, 2022) from 4:00 PM to 5:00 PM, in response to simulated combined storage in Jennings Randolph and Little Seneca reservoirs dropping to 9.9 billion gallons (BG), or 60 percent of the combined capacity.

Today we are ending daily flow and demand updates due to the arrival of rainfall from tropical storm Nicole. According to the Middle Atlantic River Forecast Center, an inch of rain has already fallen in the southern portion of the basin with more on the way, and 1 to 2 inches are expected throughout the basin upstream of the Little Falls gage over the next 24 hours.

Potomac River flow has remained relatively steady over the past week. According to National Weather Service forecasts, we can expect up to 2 inches of rain during the next three days, mainly on Friday, as the remnants of tropical storm Nicole pass over the basin.

Potomac River flow has remained relatively steady over the past week. According to National Weather Service forecasts, we can expect about 2 inches of rain during the next three days, mainly on Friday, as the remnants of tropical storm Nicole pass over the basin.

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)

There was no precipitation in the Potomac basin yesterday and none is forecast for the next three days. However, it looks like relief is on the way - there is a good chance of heavy rain late this week from subtropical storm Nicole.

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)

According to MARFC and CO-OP's Low Flow Forecast System, precipitation totals between 0 and 0.28 inches occurred yesterday. The next 72-hour forecast predicts a precipitation total of up to 0.1 inches for basin locations above the USGS gage at Point of Rocks. Longer-range forecasts (5- and 7-days) indicate heavier rain with accumulations of about an inch in the North Branch area of the basin.

Light rain is forecast in the Potomac basin over the next three days, with accumulations of up to 0.25 inches predicted for some areas. Longer range forecasts indicate heavier rain – with accumulations of about an inch - 6 and 7 days in the future. 

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)