DC-area rain levels 7 to 9 inches below normal as drought gets worse across region

Moderate drought conditions expanded across the District of Columbia area, according to a report released Thursday, as rain levels drop to 7 to 9 inches below normal this year and experts raise concerns about the impact on water supply.

The latest U.S. Drought Monitor report showed “moderate drought” — the first of four levels of drought — expanded across the larger region surrounding the district. Areas can also be designated “abnormally dry” or “none,” both of which do not classify as drought. 

The low water levels in the region can be especially noticeable when measuring flow rates in the Potomac River. On Monday, the Interstate Commission on the Potomac River Basin began daily drought monitoring after low flow rates were detected in a part of Maryland.

The flow level dropped to 1,980 cubic feet per second, below the threshold of 2,000 cubic feet per second for daily monitoring. By Wednesday, the flow rate rebounded to 2,090 cubic feet per second. 

The unusually low water levels, however, are causing some experts to raise concerns about water supply, which could result in tap water with distinct tastes and smells.

In a June 2 report, the Interstate Commission on the Potomac River Basin warned that water supply was lower than previous years but, for now, “is sufficient.” The report indicated that, in May, precipitation in the Potomac basin was 2.4 inches lower than usual, and in the year ending May 31, there was a cumulative deficit of 6.5 inches. 

“Currently, the water flow in the Potomac River is sufficient to meet the water demands of the Washington metropolitan area without requiring releases from upstream reservoirs. However, in the event of low-flow conditions, the area is well-prepared to prevent water supply shortages with hydrological drought-contingency plans,” the report said. 

The Washington Suburban Sanitary Commission said residents in the area might notice “an earthy taste” when drinking tap water, which is due to algal activity, resulting from warmer weather and low water levels.

“Despite the taste & odor issues, water remains safe,” the commission said on Twitter.

“This temporary change is not harmful and is due to an increase in a naturally occurring substance, Geosmin, caused by warmer weather and low water levels in the Potomac River,” the commission said.