New data renew concern about salt creeping into Baton Rouge's underground drinking water

In 2013, Baton Rouge Water Co. spent $3 million to drill twin wells along North Street to intercept underground salt water creeping north toward an important drinking water pump station.

Water company officials said the new “scavenger” well system would buy 30 to 50 years of additional life for the Lula Avenue station, where rising chloride levels were approaching federal drinking water limits for taste.

Now, more than a decade later, data from one of the scavenger wells show chloride levels — which reflect how much salt is in the water — have increased 16% in three years after having been being relatively stable.

Though company officials say the Lula station is safe, the Capital Area Ground Water Conservation Commission on Thursday is set to decide how to determine whether salt water is intruding faster than expected.

The Southern Hills aquifer, the area’s main source of drinking water, has faced a long-term threat from salt water moving north underground across the Baton Rouge Fault, a geological crack that generally tracks Interstates 10 and 12.

A recent analysis suggested salt concentrations from just south of the fault are similar to brackish water. Ocean water is about five times saltier than the groundwater near the fault.

Baton Rouge Water officials say they would comply with a request for data from the commission but believe a move to also launch an investigation, at a potential cost of $50,000, would duplicate that effort.

Baton Rouge Water says the chloride increases in one of the scavenger wells, which are designed to deflect the encroaching salt water, appear to reflect a coincidental shift in operations at Lula Avenue that likely changed the flow pattern of groundwater after a production well went down.

“We know the scavenger well is doing its job because the water at Lula is a good quality,” said Adrienne Mire, chief administrative officer and vice president of Baton Rouge Water. “Chloride levels remain low. Right where they’re supposed to be overall. That’s good thing.” 

The Lula Street station, just east of Acadian Thruway, has seven wells providing 8.6% of Baton Rouge Water’s overall production, though only three operate usually at any one time, company officials said.

The scavenger system south of the Lula station protects it with two wells working together. One draws off brine from a higher salinity bottom layer of the aquifer and sends that water to the Mississippi River. The other well taps the upper, less salty part of the same layer to pull in replacement fresh water from farther north.

Research done to install the scavenger system predicted it would shield the Lula street station for decades before eventually being overwhelmed by the salty water drawn toward it.

Groundwater commission member Matt Reonas, a state Office of Conservation policy planner, says that’s why it’s important to take a closer look.

A resolution to be voted on by the commission would ask for a wide range of information about affected wells and any plans for new supply options to replace those that might be threatened by saltwater. 

An expert hired for a study would review the information and make recommendations.

During a recent commission meeting, Patrick Kerr, president and CEO of Baton Rouge Water, argued that his company will provide data, so the resolution to investigate isn’t necessary.

“Let us give you what we have, and you tell us whether it’s enough. And if it’s not, we’ll work with you to write the rules to figure out how to do it better,” Kerr said. “So, we are concerned about these aquifers. We are aligned in our need to protect these aquifers.”

Reonas countered that a specific resolution to investigate is warranted.

“I feel like this commission needs to make a dedicated focus on what’s happening there right now,” he said.

The slow process of saltwater intrusion is driven by heavy pumping north of the fault.

That has driven controversy over how to reduce pumping and whether another water source should be used. Environmental groups argue major industries that tap the aquifer should use water from the Mississippi River instead.