Interstate Commission on the Potomac River Basin Newsletter — August 13, 2026 >>>
The Week’s River Report: August Water Supply Outlook
The August Water Supply Outlook was published yesterday. This monthly report provides an update on the possibility of water supply releases from the area’s reservoirs and gives an overall look at drought in the watershed.
Yesterday’s report shows improvement over earlier this summer. While the July report calculated the chance of needing to release water from upstream reservoirs was up to 48%, the August has up to a 16% chance, which is a more positive outlook for the rest of the year. However, some drought conditions remain.
Here is the full summary:
There is a near-normal probability of releases from the Washington metropolitan area’s back-up water supply reservoirs for the 2026 summer and fall seasons. Typically, the use of the Jennings Randolph and Little Seneca reservoirs is triggered by low river flows resulting from a combination of low summer precipitation and low groundwater levels.
The Potomac basin upstream of Washington, D.C., received 3.9 inches of precipitation in July, 0.1 inches above average; as of August 1, the 12-month cumulative total was 29.2 inches, 10.9 inches below average.
Groundwater conditions are generally near normal basin-wide, though above- and below-normal readings occur at individual wells.
Recent rainfall has increased Potomac River streamflow, prompting ICPRB to suspend daily drought monitoring on August 9 after initiating it on August 3 in response to declining flows.
The Climate Prediction Center’s seasonal outlook indicates drought conditions across much of the Mid-Atlantic should improve or be removed by the end of October. A Drought Watch for the metropolitan Washington region remains in effect. Reservoirs remain near full.
At present, Potomac River flow is sufficient to meet metropolitan area water demands without upstream reservoir augmentation. The region remains well protected by established contingency plans should conditions worsen.
Drought conditions remain across portions of the basin with only a slight improvement over last week. As of August 11, about 12 percent was in severe drought (D2), 44 percent in moderate drought (D1), and 37 percent abnormally dry (D0), with no area in extreme drought (D3).
Upper Potomac mapsets
We are excited to offer a new way to pay for our map sets! You can now buy them using credit card (including Apple Pay and Google Pay) for $8.00.
The five colorful strip maps of the upper Potomac cover the area from Shepherdstown, West Virginia, to Potomac Park, Maryland. A valuable resource for canoeists, hikers and outdoors enthusiasts, this map set is printed on waterproof, tear-proof paper. The maps include information on boating, public access sites, support facilities, camping and fishing sites, and picnic and parking areas. The maps are filled with cultural and historical information, safety tips, and contact information.
The Lower Potomac Map Sets (from Washington, D.C. to Opequon Creek, Md.) are currently unavailable in print but can be downloaded and printed from ICPRB’s website.
This handsome guide to the river and canal was produced by ICPRB, the Maryland Department of Natural Resources, National Park Service, and the West Virginia Division of Natural Resources.