Monitoring Reports

A little under a half inch of rain fell yesterday in Potomac watershed above Little Falls and up to ¼ inch is forecast over the next three days. Average river flow yesterday at Point of Rocks was just 2000 cfs, CO-OP’s threshold for daily monitoring. It’s likely that flows will rise slightly above this level over the next week due to the recent and forecasted rainfall. However, flows are low for this time of year, so CO-OP will continue daily drought monitoring until a significant increase occurs.

CO-OP is initiating daily drought monitoring and reporting today because Potomac River flow at the US Geological Survey’s gage at Point of Rocks, Maryland, has fallen below 2000 cubic feet per second (cfs), CO-OP's daily monitoring threshold. According to the Middle Atlantic River Forecast Center (MARFC) quantitative precipitation forecasts, cumulative rainfall ranging from 1/10 to 3/4 inch is expected in the basin over the next 3 days. MARFC ensemble forecasts do predict additional rain and rising river flows over the next 10 days.

This is the final day of the three-day 2022 WMA Drought Exercise. Simulated Potomac River flows at Little Falls have fallen to 104 MGD. Forecasts for today indicate that SIMULATED flows are expected to rise. We requested a SIMULATED Jennings Randolph water supply release this morning of approximately 30 MGD with a Luke target of 297 cfs. Little Seneca continues to make a SIMULATED water supply release to augment flows at Little Falls.

This email concludes the 2022 Washington Metropolitan Area (WMA) drought exercise. A summary report describing exercise assumptions, activities, and tools will be prepared and published on ICPRB's website (www.potomacriver.org).

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.