In the first nine months of 2017, about two billion gallons of water pumped out of the aquifer that runs beneath East Baton Rouge Parish went to customers in Ascension and Iberville parishes.

That's not enough to worry the head of the Capital Area Groundwater Commission, but one state representative said it might be time to look at ways to cut the flow of water leaving the parish.

Baton Rouge sits on a fault line that runs roughly along Interstate 10. South of the fault the groundwater is contaminated with salt, and the saltwater continues to creep northward as more and more freshwater is pumped out.

State authorities directed the privately-owned water company to turn over information revealing how much water they were pumping from the aquifer and selling elsewhere. They released the numbers this week.

Between January and September, 13.2 billion gallons were sold to customers in East Baton Rouge either through the Baton Rouge Water Company or its subsidiary, the Parish Water Company, which serves customers outside the city limits.

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During the same period, Baton Rouge Water sold two billion gallons either through its subsidiary, the Ascension Water company, or to water districts in Ascension and Iberville Parishes.

The majority of those sales went to Ascension, where the water company has a franchise agreement to serve residents on the east bank, excepting the city of Gonzales, which has its own municipal system.

Both Ascension and Iberville are outside the capital area groundwater district, which covers the parishes that sit atop the aquifer: East and West Baton Rouge, East and West Feliciana and Pointe Coupee.

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The water company isn't the only entity drawing groundwater, though it does pump more than anyone else. Industrial facilities, power companies, and towns throughout the area also collect groundwater.

Barry Hugghins, chairman of the groundwater commission, said a few billion gallons going to residents in Ascension didn't worry him.

"I don't see anything at fist glance that's traumatic. It doesn't seem like a terrible burden at this point," he said.

However, State Rep. C. Denise Marcelle, D-Baton Rouge, wants to consider options for keeping water in the parish where it's being pumped. She got legislation passed earlier this year that requires the groundwater commission to submit periodic reports on the health of the aquifer. The first report was issued this week and prompted the release of the water company's pumping data.

The groundwater commission collects pumping fees from entities that draw water from the aquifer. However,  under existing law the commission can't charge different pumping fees to different users. In 1988 it passed a resolution reserving one level of the aquifer for the drinking supply — meaning it couldn't be tapped by industrial facilities — but it's never prevented the sale of water outside the district.

Marcelle wants to discuss potential changes to the status quo, such as higher fees for water transported out of the district or limits on those sales.

"This is a conversation worth having," Marcelle said. "I am concerned about the amount of water we are sending out of the parish."

The water company has steadfastly defended its business in Ascension. Many customers in East Baton Rouge live on the salty side of the fault line too, they've pointed out.

"We have thousands and thousands of customers south of Interstate 12 ... Those people in East Baton Rouge Parish, are they not entitled to good quality drinking water?" Vice President Hays Owen said in a recent interview.

It would be unreasonable to charge the water company a higher rate than industrial users, he continued. After all, companies like Georgia Pacific and ExxonMobil — the second and third largest users — pump water to make products that are sold outside the area, Owen said.

The water company has called for industrial users to switch over to Mississippi River water, which has to be cleaned before use. The industrial users have pushed back at the suggestion, and both Georgia Pacific and Exxon said they've already invested in strategies to use some river water or to tap  groundwater from shallower, less desirable parts of the aquifer.

Engineer Hays Town of the environmental group The Green Army said the local groundwater is so valuable because it's naturally filtered through gravel and sand, which removes minerals and chemicals, according to engineer 

Some places have groundwater not just with salt, but with sulfur or even arsenic.

"Our water is ninety-nine percent pure," he said.

Drawing drinking water from the river would make it more expensive, and it wouldn't taste as good, Town said. For that reason, he sided with the water company and said the aquifer should be preserved for human consumption — whether the people drinking it are in Baton Rouge or Galvez.

Follow Steve Hardy on Twitter, @SteveRHardy.