‘Hot drought’ could affect Potomac River drinking water supply
During summers in and around D.C., the risk of drought was always there, and now a group that coordinates with area water companies said it will continue to get harder to ensure there’s enough water in the Potomac River.
A new study, by the Interstate Commission on the Potomac River Basin shows that “future Potomac River flows we be impacted by ‘hot drought’, that is, increasing drought severity caused by rising temperatures coupled with natural variability in precipitation.”
“Because of climate change, it’s hard to talk about the ‘100 year drought’ anymore,” says study author Dr. Cherie Schultz, director for CO-OP Operations at the Interstate Commission on the Potomac River Basin.
Even though precipitation amounts are expected to rise by up to 16% by 2099, annual river flows may fall by as much as 49% due to extreme heat, Schultz said.
“Temperature tends to dry things out. It leads to more evaporation from the ground, and from water surfaces, to that effect will counteract the phenomena of increased precipitation,” said Schultz.
Updating Plan B for Potomac River drought
The Washington Aqueduct, which processes drinking water for D.C., Arlington County and the City of Falls Church, plus the Washington Suburban Sanitary Commission, which serves Montgomery and Prince George’s counties, as well as Fairfax Water, which also serves Prince William County share upriver reservoirs, that could be released into the Potomac River in the event of extreme drought.
The last times releases were needed were 2010, 2002 and 1999.
However, Schultz said with rising temperatures the Interstate Commission on the Potomac River Basin is instituting new modeling, informed by the “hot drought” research to more quickly anticipate when backup releases may be needed: “To simulate what’s going to happen in the future, and to help understand what resources are needed.”
Currently, there is no backup water supply for D.C., Arlington County and the City of Falls Church.
WTOP initially reported in 2016 that water officials were finally making public a long-standing water system shortcoming — the Washington Aqueduct, which processes water from the Potomac River, only has 24 to 48 hours of water supply available.
The U.S. Army Corps of Engineers is in the midst of a study to increase the stability of the D.C.-area’s water supply.
“The Corps’ feasibility study is looking for ways to increase backup supplies,” said Schultz.