News from Around the Basin – June 22, 2023

Find information on the continued historical low flows, US Navy sued, mussels, eels, and more in this week’s Potomac News Reservoir…

Rain returns, but we’re not out of the (dry) woods just yet

If you caught last week’s newsletter, you saw that we started actively monitoring drought conditions on June 12 due to low flows in the Potomac River. Staff in ICPRB’s Section for Cooperative Water Supply Operations on the Potomac (CO-OP) were able to stop drought monitoring 5 days later after subsequent rain storms across the basin.NWS Middle Atlantic River Forecast Center 9 day forecast.

The Potomac River is known as a “flashy” river, meaning it can rise and fall suddenly. That has been particularly evident over these past few weeks when we went from drought monitoring to possible minor flooding in only a week or so. If we get the upcoming several inches of rain predicted by the NWS Middle Atlantic River Forecast Center, some areas of the Potomac basin will experience flow levels of minor to moderate flooding.

Even with the rain, we may continue to experience a hydrological moderate drought in the watershed. See the video by NBC4’s meteorologist Ryan Miller for an explanation of the difference between a hydrological and meteorological drought in the Potomac watershed. Both the Pennsylvania Department of Environmental Protection and officials in Front Royal, Virginia, have recently made the call for voluntary water conservation.

According to our Director of CO-OP Operations, Dr. Cherie Schultz, “If we get 2 inches of rain in the next few days, it is not going to erase the [rain] deficit but we will be out of extremely dry conditions and it will help. We still face the likelihood of drought operations this summer unless we continue to get more rain events.”

The graph above shows Potomac River’s adjusted flows at Little Falls (black line) headed in the right direction, but still on the low end.NWS Middle Atlantic River Forecast Center 9 day forecast.

What would happen to our water supply during a drought? The DC Metro area is well protected due to careful planning and coordination among ICPRB and our partners. See a video of Dr. Schultz’s presentation during yesterday’s quarterly business meeting on the status of the current drought, how it relates to historical droughts, and what would happen if flows drop very low.

Current Potomac River Conditions

Several inches of rain is predicted over the next few days and should bring us closer to the median (gray line) for this time of year. However, despite the expected rain, we will most likely remain below average. (Graph: USGS gage at Point of Rocks)

Current flow: 2280 cfs

Median flow: 4970 cfs

90 Day Precipitation:

3.6 inches below average