Work underway to protect water supplies in DC, Virginia

Aug 10, 2023

Little Seneca Reservoir in Boyd, MD, is an example of an emergency water source that could supplement main sources like the Potomac River in the Washington, DC, area during a drought. Recent reports have found more backup sources are needed. (Renee Bourassa)

The Chesapeake Bay region is generally considered rich in water supplies, with rivers that are more likely to flood than to run dry. But growing industrial and residential demands on water supplies, combined with the potential for contamination and ongoing climate variability, mean no water source is immune from crisis.

The issue has recently bubbled to the surface in the Washington, DC, area and in Virginia, where plans are underway to better prepare for an unpredictable future.

Take the Potomac River. An average of 486 million gallons of water is withdrawn from the river daily to supply drinking and other water needs, according to the Interstate Commission on the Potomac River Basin.

Those withdrawals supply about 86% of the DC area’s population. Another 100 million gallons of water are pulled from the groundwater in the surrounding rural areas of the Potomac’s basin, the commission found. The commission completed a study in 2020 looking at water resource and demand forecasts for the year 2050 and found a need for some contingency plans.

If the water intakes from the Potomac River needed to be shut down for some reason, many communities would be out of an ongoing water supply within a day. The 2020 study found a need for an additional reservoir to be constructed to shore up the area’s water supply. At the time, an existing quarry in Montgomery County, MD, was suggested as having the potential to be converted to a reservoir — at cost of $800 million.

“The time to start planning for such a facility is now,” a summary of the 2020 study states.

Cherie Schultz, director for co-op operations at the commission and one of the study’s authors, said the quarry project is just one of many options on the table as part of a much bigger effort to look at the issue.

The Water Resources Act of 2022 authorized the U.S. Army Corps of Engineers to study what might be the best options for a secondary water source for the region should the Potomac River be taken out of commission for any length of time. That study, which still needs funding, would look at options to create an additional drinking water source or storage solution in the case of a spill or severe drought in the Potomac River.

Schultz said the Potomac commission and other partners are trying to get the word out about this vulnerability for the region and the need for a secondary source before it’s too late to act. Droughts across the Western U.S. plaguing the Colorado River, for example, have made these scenarios more plausible than before, with climate scientists suggesting that both flooding and droughts could worsen in the future.

New homes like these that were being built in 2019 in Fredericksburg along the Interstate 95 corridor could be one of the drivers for a fresh look at water supply allocations underway in Virginia.

The region is no stranger to significant drought conditions.

Virginia started its Office of Water Supply in the early 2000s after a historic drought ushered in water restrictions and policy changes. Twenty years later, “we have more folks and more demand, and it would be a lot more difficult to provide adequate water for all the uses,” said W. Weedon Cloe III, who manages the office.

For that reason, the Virginia General Assembly passed a law in 2020 directing regional planning areas to assess potential risks to their local water supplies. Many of the regional planning areas in the state are based around river basins, drawing water from the Rappahannock or the James rivers, for example.

But another Virginia bill in 2022 added a provision that would allow local governments to request to be assigned to a neighboring planning area, factoring in not only river basin boundaries but also where localities are seeing the most population growth and water demand.

The 2020 bill had required localities to get their new plans submitted to the Virginia Department of Environmental Quality by the end of 2023. But that deadline was extended while the new provision was still receiving public comments this summer and being finalized.

Brent Hunsinger, river steward and state policy coordinator for the Friends of the Rappahannock, said water supplies and allocations top his list of concerns. Where the water goes is driven by so many of the same factors that impact water quality and living organisms.

“Going forward, how do we make sure people have water and we have the baseline flows [in the river] to support fish and ecology?” he said.

Hunsinger is particularly concerned about the potential, under the 2022 provision, for water to be drawn from one river basin and discharged into a different one. This sort of reallocation sends water where it’s needed for growing populations and industrial needs, such as cooling systems for data centers.

But it could also reengineer natural systems in a way that would lower their flows and impact their functions over time. One particular concern is that advocacy groups like Hunsinger’s can’t always know how much water a new data center is proposing to use for cooling purposes because the details are often protected by nondisclosure agreements.

Cloe said that all of the public comments on the amendment are being taken into consideration, and the public will have the chance to comment again before the measure is finalized. He also said DEQ conducts a “cumulative impact analysis” that takes into account the total volume of withdrawals from a river when deciding whether to grant permission for a new withdrawal.

Predicted water needs also don’t always pan out the way experts expect. Water demand in the DC metro area, for example, remained about the same from 1990 to 2020 despite a 41% increase in population, the commission report found. Some factors can free up large amounts of water supply for other users — like when a paper mill in Maryland closed in 2019.

“We try to forecast water use in 20 years, but we always get it wrong,” Schultz said. “We have models that try to account for the increasing efficiency, but we underestimate it.”

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