New Report Exposes our Region’s Water Vulnerability

 

From a new release from the ICPRB:

We have always assumed when we turn on the tap, there will be water; but that is not true for everyone and may not always be true for us in the DMV. New research from the Interstate Commission on the Potomac River Basin (ICPRB) notes that changing weather patterns and increased water demand from data centers are putting a strain on the region’s water supply. Without significant investment in water infrastructure this may have dire consequences according the ICPRB.

The report, 2025 Washington Metropolitan Area Water Supply Study - Demand and Resource Availability Forecast for the Year 2050, shows that the region will have plentiful water most years, but there is an increasing chance — up to about 1 percent in 2030 and up to about 5 percent in 2050 — that there will be water shortages. This is when there is not enough water to meet the demands of the water users while still leaving enough water in the Potomac River to protect the sensitive aquatic habitat below Little Falls Dam.

According to the report, despite exponential population growth in the region, overall water use had stayed remarkably stable over the past several decades due to the use of low flow fixtures and appliances. Water use in general peaked in 2005; however, the ICPRB predicts an increase in water demand in the coming decades, with a 17 % increase in water use by 2050. This translates to a rise from approximately 465 million gallons per day (MGD) to about 538 MGD. For the first time, the study specifically evaluated the impact of data centers. It found that their upstream water use is expected to grow substantially, potentially consuming up to 80 million gallons on peak days by 2050. So that population water use will continue to decline.

In addition to more overall water demand, the river’s flow may be impacted by predicted changes in temperature and precipitation through a process that has been characterized as “hot drought” by ICPRB. “Results from our study indicate that extreme hydrological droughts may become more severe due to increasing temperatures," explains Dr. Cherie Schultz, Director of ICPRB’s Section for Cooperative Water Supply Operations on the Potomac. “A major uncertainty in many regions, including the Potomac, is the response of future stream flow to the competing effects of temperature change and precipitation change. Rising temperatures will tend to decrease flows due to increases in evaporation, while predicted increases in precipitation will tend to increase flows,” continued Dr. Schultz. “It is changing weather patterns combined with the increase in demand that may be putting the whole system at risk,” states ICPRB Executive Director Michael Nardolilli.

The study estimates that during an extreme drought event, changes in river flow could range from a 3% increase to a 25% decrease for the period 2010–2039. This potential for flow reduction worsens over time, with a projected range of a 9% increase to a 32% decrease in flow for the period 2040–2069, depending on how sensitive flows are to rising temperatures. The study uses climate change data derived from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to model these future impacts. Though, the water supply planning is primarily tested against the risk of a future extreme drought similar in severity to the 1930 drought  the worst the region experienced on record.

The data center forecast estimates are based on grid-connected energy forecasts, which are rapidly evolving as the sector continues to expand. In the Washington metropolitan area, data centers could use as much as 80 million gallons on peak days by 2050. This could signal the growing significance of data centers in the region’s water demand. The report notes that balancing energy, water, regulations, and infrastructure constraints may be needed to strengthen resiliency in this sector. One step forward would be to improve transparency around data center water use. The majority of the Washington metropolitan area’s water supply is provided by the Potomac River.

from ICPRB

While most regions have two or more sources of water, the Potomac River is the only source of drinking water for the residents of Washington D.C. and Arlington County. Two upstream reservoirs, Jennings Randolph and Little Seneca, are available to release water to augment Potomac River flow should the river get too low to meet the region’s demands. In addition, off-Potomac reservoirs, Fairfax Water's Occoquan Reservoir and WSSC Water's Patuxent reservoir, are used to partially meet these suppliers' demands. According to the study, four out of nine modeled scenarios predict that in the event of an extreme drought, the upstream reservoirs will run out of water as early as 2030, indicating that short-term measures should be taken to improve reliability.

Some short-term solutions are already in the works. Improvements in ICPRB’s river flow forecasts can help water resource planners better predict when to release water from upstream reservoirs. A water reuse project recently announced by DC Water, dubbed Pure Water DC, aims to create a more resilient water source for residents of the District. Two drinking water reservoirs currently in the planning stages, Loudoun Water’s Milestone Reservoir (expected operational by 2028) and Fairfax Water’s Edgemon Reservoir (expected operational by 2040), were already included in the report’s calculations.

The U.S. Army Corps of Engineers, Baltimore District, initiated a D.C. Metropolitan Area Backup Water Supply Feasibility Study last fall which could lead the way to possible long-term solutions. However, with federal funding issues hanging in the balance, it is unclear when that study will be completed.  “We can no longer ignore the fact that parts of the DC region have only one source of drinking water – the Potomac River – and just a one-day back-up of water supply. Today’s release of the 2025 Washington Metropolitan Area Water Supply Study highlights the need to expedite the study so that we can reduce the vulnerability of the DC region from a cutoff of drinking water because of drought or contamination events (both accidental and deliberate),” explained Nardolilli.

“This report confirms the need for innovative and cooperative approaches, as well as funding, to secure the water supply for our region,” said WSSC Water General Manager and CEO Kishia L. Powell. “The Potomac River has provided the vast majority of the region’s drinking water for generations. But climate pressures and growing demand will impact our ability to meet the region’s needs in just a few years. This report makes clear that we need to continue with substantial investments to safeguard public health, enhance reliability and resiliency, and ensure the long-term economic vitality of the region.”

 An earlier study released by ICPRB found that a significant water supply disruption could result in losses of almost $15 billion in gross regional product and hundreds of millions in tax losses, all within the first month. “For nearly 50 years Fairfax Water, WSSC Water, the Washington Aqueduct and ICPRB have been working together to ensure adequate water supply for the Washington Metropolitan Region now and into the future” said Fairfax Water General Manager and CEO Jamie Bain Hedges. “This study further advances our collective mission to supply life’s most essential service for decades to come.” The water supply study released on December 5^th is conducted every five years by the Section for Cooperative Water Supply Operations on the Potomac (CO-OP) of the Interstate Commission on the Potomac River Basin (ICPRB) on behalf of the three major water suppliers: Fairfax Water, WSSC Water, and the Washington Aqueduct. This is the first year that the study has explored the impacts of data centers on the water supply.