Federal Water Tap, September 9: Army Corps Again Builds Underwater Barrier in Mississippi River to Block Salt Water

The Rundown

• Army Corps builds a temporary barrier on Mississippi River bed to block upstream movement of salt water that threatens municipal drinking water.
• EPA announces $7.5 billion in low-interest financing for water infrastructure.
• Department of Commerce agency wants to know about water and energy obstacles to data center growth in the United States.
• EPA hosts a webinar on wildfire damage to water infrastructure.
• DOE selects hundreds of hydropower dams to receive funds for safety, operational, and environmental improvements.
• U.S. Geological Survey publishes a report on saltwater intrusion of groundwater in the Baton Rouge area of Louisiana.

And lastly, the Bureau of Reclamation begins a critical repair to Glen Canyon Dam’s river outlet works.

“It is Reclamation’s duty and obligation to operate all of our facilities – including Glen Canyon Dam – in a safe manner and to maintain reliable downstream releases to meet the nation’s water and energy needs. The relining of the outlets ensures Glen Canyon Dam continues to operate in a manner that meets its congressionally authorized purposes safely and efficiently well into the future.” — Wayne Pullan, Bureau of Reclamation Upper Colorado Basin regional director, in a press release highlighting repairs to Glen Canyon Dam’s river outlet works. The four large pipes, which move water from Lake Powell downstream, draw water from deep in the reservoir. Rarely used today, they could be employed more often for two reasons: if Lake Powell continues to drop or if more cold water needs to be released to combat non-native fish downstream, which prefer warmer water.

By the Numbers

3: Consecutive years in which the Army Corps of Engineers has built a barrier on the bed of the Mississippi River to block salt water from the Gulf of Mexico moving upriver.

$7.5 Billion: Low-interest loans the EPA will make available through the WIFIA program. Because the program can finance up to 49 percent of a project’s total cost, the federal funding will facilitate roughly $15 billion in water infrastructure upgrades. Most of the financing goes directly to utilities. The reminder will be directed through state infrastructure financing authorities.

293: Hydropower projects in 34 states selected to receive $430 million in Department of Energy funding for upgrades. The upgrades include fish passage, new generating equipment, and safety improvements to spillways and embankments.

News Briefs

Saltwater Again Moves Upriver in Louisiana
Dry weather and slack flows in the Mississippi River have combined to once again threaten the drinking water supply for southern Louisiana communities that draw water from the river.

Because the river flow is weak, salt water from the Gulf of Mexico is pushing inland. As a defensive measure the Army Corps of Engineers is now building a temporary barrier on the river bottom to impede the salt water. Because it’s denser than fresh water, the saltwater “wedge” moves along the river bed.

As of September 6, the wedge is 45 miles upstream of the river mouth. The barrier, made of dredged sediment, will be built 64 miles from the mouth.

This is the third consecutive year and sixth time overall that the Corps has built the barrier.

Last summer, salt water moved 65 miles upriver – such a distance that the Corps barged drinking water to several communities in Plaquemines Parish, in the southernmost reaches of the delta.

The Army Corps notes that the saltwater intrusion is a matter of physics. Starting just south of Natchez, Mississippi – some 348 miles from the river mouth – the bed of the Mississippi is below sea level.

Studies and Reports

Saltwater in Louisiana Groundwater
The Mississippi delta is not the only spot in Louisiana contending with salty water.

The U.S. Geological Survey published a report on saltwater intrusion into groundwater in the Baton Rouge area.

Industrial and municipal users are overpumping the regional aquifer system, which is allowing salt water to infiltrate. Each of the 10 aquifer layers from which water samples were taken displayed varying levels of saltwater intrusion.

The sampling begins to address a critical data gap. The report mentions that water managers don’t have much of an early-warning system to track the movement of saltwater plumes.

“There are few operable monitoring wells between known areas of intrusion and currently producing wells to provide advance warning, information on the rate of encroachment, or water level data to constrain hydraulic gradients.”

Data Center Water and Energy Use
A Department of Commerce agency is soliciting public input on obstacles to data center growth in the United States.

Among its many questions, the National Telecommunications and Information Administration wants to know about water and energy constraints. Will they affect operating costs or limit expansion in certain areas? Answers will inform a report with policy recommendations for the federal government.

Submit responses by November 4 via www.regulations.gov using docket number NTIA-2024-0002.

On the Radar

Wildfire and Water Infrastructure Webinar
On September 11, the EPA will host a webinar to discuss how wildfires can contaminate drinking water pipes with benzene and other harmful chemicals.

Three EPA staffers will speak during the webinar and focus on the agency’s response to the August 2023 fires on Maui.

Register for the webinar via the above link.

House Wetlands Hearing
On September 11, a House Transportation and Infrastructure subcommittee will hold a hearing on federal permitting after the Supreme Court’s Sackett decision, which restricted federal oversight of wetlands and ephemeral streams.

Federal Water Tap is a weekly digest spotting trends in U.S. government water policy. To get more water news, follow Circle of Blue on Twitter and sign up for our newsletter.

Brett Walton

Brett writes about agriculture, energy, infrastructure, and the politics and economics of water in the United States. He also writes the Federal Water Tap, Circle of Blue’s weekly digest of U.S. government water news. He is the winner of two Society of Environmental Journalists reporting awards, one of the top honors in American environmental journalism: first place for explanatory reporting for a series on septic system pollution in the United States(2016) and third place for beat reporting in a small market (2014). He received the Sierra Club’s Distinguished Service Award in 2018. Brett lives in Seattle, where he hikes the mountains and bakes pies. Contact Brett Walton