River Report: Water supply outlook for June
Today’s U.S. Drought Monitor map of the Potomac watershed is a sight for dry eyes, with only 37% abnormally dry and 0% in all other categories.
Each month, ICPRB looks deeper into the data when staff at ICPRB’s Section for Cooperative Water Supply Operations on the Potomac (CO-OP) publishes a report exploring the current conditions and the probability of water supply releases from upstream reservoirs, which is an indicator of regional drought. In this River Report, we’ll highlight excerpts of the recently published June Water Supply Outlook.
The probability of needing water supply releases from the Washington metropolitan area’s backup reservoirs during summer and fall 2025 is elevated.
As of early June, drought conditions in the Potomac River basin have shown modest short-term improvement following above-normal rainfall in May. Data from the National Weather Service’s Middle Atlantic River Forecast Center (MARFC) show that the Potomac basin upstream of Washington, D.C., received 6.2 inches of precipitation in May—2.9 inches above normal. As of May 30, the 12-month cumulative precipitation is 34.5 inches, which is 4.9 inches below normal.
While recent rain has boosted streamflows and improved groundwater levels in some areas, conditions remain mixed, and improvements may be tapering off…long-term deficits persist. Drought watches and warnings remain in effect across parts of Maryland, Virginia, and Pennsylvania, including the ongoing MWCOG drought watch, expected to be reviewed in June or July.
According to recent U.S. Geological Survey (USGS) data, groundwater conditions across the region are mixed. Some wells remain much lower than normal, indicating ongoing dry conditions…other wells show higher-than-average levels, likely due to recent rainfall.
The Climate Prediction Center’s May 31 outlook indicates likely drought improvement in the Potomac River basin by late August. However, in their discussion the Center warns that long-term precipitation deficits—especially in parts of Maryland, West Virginia, and Pennsylvania—may persist due to low streamflows and groundwater levels, and that even brief periods of hot, dry weather could trigger a quick return of drought conditions.
If low-flow conditions develop, the region is protected by well-established drought contingency plans.
Best wishes in retirement
ICPRB staff would like to give a fond farewell to Andrea Nagel, our longtime Senior Environmental Scientist. Andrea retired last week after 24 years of service to ICPRB.
If you are familiar with ICPRB products, you have undoubtably admired her work. As a GIS expert, she was responsible for many of ICPRB’s informative maps highlighting features of the Potomac River watershed, as well as complex geospatial analyses required for ICPRB efforts like the land prioritization tool. She was the co-author of at least 22 ICPRB publications, many related to her technical work on TMDLs.
We all wish her the best of luck in her retirement!
ICPRB’s upcoming third quarter business meeting
The ICPRB Third Quarter Business Meeting is coming up on Tuesday, June 17, 2025. The meeting will be held virtually on Teams. Commissioners will discuss progress made on the Low Flow Allocation Agreement and get an update on ICPRB’s Land Use Webinar Series. Find the draft agenda on our Business Meetings page.
The public is invited to view the virtual meeting or provide public comment. Please contact us by Friday, June 13, for more information on how to attend.
ICPRB in the community
Please join us at one of our upcoming events:
- June 14 – Walk in the Woods: Potomac Fever (Chevy Chase, MD)
- Jul. 11 – RiverPalooza: Shenandoah Snorkeling Paddle (Bentonville, VA)