Water Supply Outlook and Status

Interstate Commission on the Potomac River Basin

What is the Outlook?

A drinking water reservoir lake with a blue sky. Dam is seen in the background.

Little Seneca Reservoir

ICPRB’s Section for Cooperative Water Supply Operations on the Potomac (CO-OP) was established to serve as a cooperative technical center on water resources in the Potomac basin. CO-OP staff publish the Water Supply Outlook on a monthly basis between April and October of each year. It provides an update on the possibility of water supply releases from the area’s reservoirs based on long-term precipitation data, flows, and other information for the Potomac basin.

Download: Water Supply Outlook – April 2024

The monthly Water Supply Outlook has returned to its normal schedule for 2024. The next report will be released in May.


The probability of releases from backup water supply reservoirs in the Washington metropolitan area during the summer and fall seasons of 2024 is currently below normal. The use of Jennings Randolph and Little Seneca reservoirs is generally triggered by low flows brought about by a combination of low summer precipitation and low groundwater levels. Streamflow is currently above normal, and groundwater levels are mostly above normal. The Potomac basin upstream of Washington, D.C. received 3.2 inches of precipitation for the month of March, which is 0.3 inches below normal. After an extended dry period from spring to fall 2023, precipitation has been near-normal to above normal for the past few months. As of March 31, the 12-month cumulative basin precipitation was 3.8 inches below normal. Rainfall in the first week of April has been much above normal. The Middle Atlantic River Forecast Center (MARFC) anticipates no water supply shortages within the Mid-Atlantic region over the next couple of months, assuming continuation of near normal precipitation. At present, there is sufficient flow in the Potomac River to meet the Washington metropolitan area’s water demands without releases from upstream reservoirs. If low-flow conditions develop, the Washington metropolitan area is protected from a water supply shortage owing to carefully designed drought-contingency plans.

Drought Status:

Recent precipitation and forecasts:

Groundwater Conditions:

Water Supply Outlook Archive:

2024: April

2023: April | May | June | July | August | September | October | November* | December*

2022: April | May | June | July | August | September | October

2021: April | May | June | July | August | September | October

2020: April | May | June | July | August | September | October

2019: April | May | June | July | August | September | October

2018: April | May | June | July | August | September | October

2017: April | May | June | July | August | September | October 

2016: April | May | June | July | August | September | October

2015: April | May | June | July | August | September | October

2014: October

*Due to the persistent dry conditions, the publication period for the Water Supply Outlook was extended.

Please contact us if you would like to be notified when new Water Supply Outlooks are posted.