During a drought, ICRPB coordinates water supply operations for the three major water utilities in Washington, D.C., and the adjacent suburbs in Maryland and Virginia. In preparation for such an event, ICPRB and the utilities practice communications and simulate operations of the system as they would occur during an actual drought.

ICPRB’s CO-OP Section conducts an Annual Drought Exercise in years in which no actual drought operations occur.

Past Drought Exercises

• 2023: The Washington, DC, metropolitan area experienced unusually dry conditions in the summer and fall of 2023, and flows in the Potomac River fell to levels requiring the Interstate Commission on the Potomac River Basin (ICPRB) Section for Cooperative Water Supply Operations on the Potomac (CO-OP) to conduct drought response activities in support of the major regional water suppliers: Fairfax Water, Loudoun Water, WSSC Water, and the Washington Aqueduct, a Division of the U.S. Army Corps of Engineers. In lieu of a drought exercise, the 2023 CO-OP Drought Operations Report provides a brief summary of these activities and of related issues and discussions that arose.
• 2022: The 2022 Drought Exercise included the following elements: A regional Drought Coordination Technical Committee conference call to discuss potential water use restrictions associated with the Metropolitan Washington Council of Governments “Warning” stage; Communication with Washington Aqueduct on the Low Flow Allocation Agreement thresholds, and; Data collection and operational forecasts through CO-OP’s Data Portal and daily flow forecast tool to determine the need for “simulated” releases from Little Seneca and North Branch reservoirs.
• 2021: During the 2021 season, actual daily drought monitoring was conducted from July 27 through August 16, and during that time CO-OP and utility staff updated drought operations models and communications procedures.
• 2020: During the 2020 Drought Exercise, water suppliers and CO-OP staff practiced communications and procedures that would be used in an actual drought, including the exchange of information via CO-OP’s Data Portal website, and CO-OP staff made use of the latest version of the R/Shiny application to support simulated drought operations decision-making. The exercise included two special events: an actual test release from Little Seneca Reservoir, and a webinar by Hazen & Sawyer on forecast informed reservoir operations.
• 2019: A 3-day drought exercise tested a new drought operations Shiny app by using actual flows (and demands) scaled down (and up) to simulate drought conditions. No report was created for the 2019 Drought Exercise.
• 2018: ICPRB designed the 2018 Drought Exercise with two objectives: To test the mechanisms in the Low Flow Allocation Agreement for allocating water during an extreme drought, and to explore the interactions between multiple drought management plans that encompass the Potomac River and the Washington Metropolitan Area.
• 2017: The 2017 Drought Exercise simulated a moderate drought and provided CO-OP staff with experience in using a number of data download and flow forecast tools. The scenario and schedule are available. A report was not generated for this event.
• 2016: A special focus of the 2016 Drought Exercise was drought operations during a regional power outage. Participants explored their organizational and system backup capabilities and vulnerabilities.
• 2015: The scenario for the 2015 Drought Exercise was autumn low flow conditions, and one of the focuses of the exercise was potential operational considerations that might arise during WSSC’s planned rehabilitation of Brighton dam in coming years.
• 2014: The 2014 Drought Exercise focused on vulnerabilities of regional drought operations during a power outage.
• 2013: The 2013 Drought Exercise focused on understanding and improving flow prediction tools.
• 2012: The 2012 Drought Exercise simulated operational decisions and the declaration of water use restrictions during a severe drought. The scenario assumed that the year was 2022 and that operations were coordinated with Loudoun Water.
• 2011: The 2011 drought exercise aimed to familiarize CO-OP staff and member utilities with the Potomac OASIS model. The model makes probabilistic forecasts that could help inform future drought operations. The exercise used stream flows based on the 2002 low-flow period and projected 2015 demands and reservoir sedimentation rates.