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 5th 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.
