Rockville quarry eyed as future 17.4 billion gallon reservoir

ROCKVILLE, Md. — A working quarry in Rockville could someday become a 17.4 billion gallon water storage facility for the D.C. region, according to a new study from the Interstate Commission on the Potomac River Basin.

The study was published as the Commission released an analysis that warns the capital region is uniquely vulnerable to catastrophic economic consequences from a disruption in water supply from the Potomac River— the sole source of water for 5 million people.

The analysis predicted the region would suffer a $15 billion economic impact in the first month should the water supply from the Potomac River be cut off by drought or other environmental disaster such as an oil spill.

“This report makes clear a disruption to our region’s water supply would have catastrophic and long term economic consequences for the Nation’s Capital," said Mae Stevens of the American Business Water Coalition.

DC Water CEO David Gadis warned the system serving the District of Columbia and much of Arlington, Va. has only a 24-hour supply of water.

Water for the system is supplied by the Washington Aqueduct which is operated by the U.S. Army Corps of Engineers and is 100% dependent on the Potomac River as its source of raw water.

The quarry conversion study comes as water planners and economists remain deeply worried about climate trends leading to historic droughts, or environmental disasters crippling the system.

A wake up call came during the summer of 2024 when alarmed authorities feared the water treatment capability of the Washington Aqueduct had been compromised by an algae bloom linked to a heat wave and low flows in the Potomac River.

The U.S. Army Corps of Engineers was forced to issue a precautionary boil water order before quickly getting a handle on the situation and calling off the advisory.

The Travilah Quarry, currently operated by Holcim US, is a major supplier of stone and aggregate used in concrete and other construction in the region.

Full mining of the area could carry on until 2060 and expand the quarry to the 17.4 billion gallon capacity according to the ICPRB study.

The study says the quarry could be filled with water pumped from the Potomac, and could be connected to the Washington Aqueduct.