The developer of a proposed $4.5 billion carbon capture pipeline in Iowa must release the names of landowners who could be impacted along its roughly 680-mile route, a district judge ruled.

Summit Carbon Solutions, an Ames company that has proposed building a pipeline to transport liquefied carbon dioxide, failed to win a permanent injunction to keep secret the names of thousands of landowners it said could be in the pipeline's path.

Under state law, Summit was required to hold public meetings for landowners potentially impacted by the pipeline project, and the company compiled a list with more than 10,000 names along the route.

After the Iowa Utilities Board asked Summit to submit the names, the company asked state regulators to keep the list confidential. Summit also filed a petition with the court to keep the names secret.

The Sierra Club of Iowa asked regulators to release the names under state's open records law, a move state Consumer Advocate Jennifer Easler also supported.

In November, the Iowa Utilities Board decided it would keep secret most of the names, saying property owners' right to privacy outweighed the public's interest. The three-person board did, however, order Summit to release the names of businesses, cities, counties and other government entities that own land along the path.

Board chairwoman Geri Huser dissented, saying she would have released the property owners' mailing addresses but not their names.

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On Friday, Polk County District Judge David Nelmark said Summit had failed to show landowner information should be excluded from state public records law. He ordered a temporary injunction allowing Summit to keep landowner names confidential to be lifted in 14 days.

Nelmark said the order's enforcement could be delayed if there is an appeal to the Iowa Supreme Court.

Summit officials said Monday the company was reviewing Nelmark's order and its legal options.

The Sierra Club has said Summit seeks to prevent the release of landowner information to shut down communication among Iowans who want to fight the pipeline.

MORE: Iowa politics, ag heavyweight Bruce Rastetter sets sights on $4.5 billion carbon capture pipeline

"Summit vigorously fought to keep the landowner list confidential so the landowners could not form a unified opposition,” Jess Mazour, the Sierra Club's conservation program coordinator, said in a statement Monday.

Summit said in its own statement Monday that it sought to "protect the privacy of our landowners and from harassment."

"We believe it is reasonable that landowners would get to choose whether or not their name, address and contact information are made public," the company said. "Having now signed agreements with more than 700 Iowa landowners, we believe our efforts were successful."

The company also said the information shouldn't be publicly released because to do so would help its competitors. Two other companies — Navigator CO2 Ventures and Archer Daniel Midlands Co., partnering with Wolf Carbon Solutions — plan similar projects.

MORE: Iowa politics, ag heavyweight Bruce Rastetter sets sights on $4.5 billion carbon capture pipeline

The Sierra Club released a copy of the order Monday. It hadn't yet been filed in district court.

Summit Carbon Solutions, a company that agri-industry entrepreneur Bruce Rastetter started, proposes to capture carbon dioxide emissions from ethanol plants and other industrial agriculture operations in Iowa and four other states, then liquefy the gas under pressure and transport it to North Dakota, where it would be permanently sequestered deep underground.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com or 515-284-8457.