At least 15 people were arrested Saturday during a protest intended to block the construction of a major oil pipeline through southeast Iowa.

More than 150 protesters gathered at the work site entrance of the $3.8-billion US Dakota Access Pipeline in Sandusky, a Mississippi River town across the river from Illinois and eight kilometres north of Missouri.

Protesters were arrested after walking through a line of private security and Lee County sheriff's deputies who were standing in front of the driveway to the work site, according to the Burlington Hawk Eye newspaper.

Last month, 30 protesters were arrested at different pipeline construction site in Iowa on trespassing charges. All but one of them took responsibility for the action and were ordered to pay just over $270 US in fines and fees. One pleaded not guilty and faces a trial.

The pipeline would stretch 1,886 kilometres over four states once complete, transporting oil from North Dakota's Bakken formations to Illinois. It also would cross 18 Iowa counties.

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A group of people hold signs as they prepare to trespass into a Dakota Access Pipeline construction site. (Erin Lefevre/The Hawk Eye via AP)

Saturday's peaceful protest was organized by a 35-year-old Des Moines woman, Jessica Reznicek, who has been camped just outside the work site after getting arrested twice for blocking its entrance last month.

"We have a great influx of folks who come in on the weekends and support us when they can," Reznicek said.

'Precedent for oil pipelines leaking or breaking'

Protester Carolyn Scherf of Dubuque said she's concerned the finished pipe could leak or break and contaminate rivers. Scherf says protesters successfully stopped work on the pipeline on Saturday.

"There's precedent for oil pipelines leaking or breaking," Scherf told the Dubuque Telegraph Herald. "If that were to occur under the Mississippi River, we would be in trouble."

Brenda Knox of Donnellson said she fears the pipeline would harm Iowa's soil if it leaked.

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From left, Eraylee Lee-Slough, Fable Lee-Slough and Miriam Timmer Hackert pose for a selfie during Saturday's protest. (Erin Lefevre/The Hawk Eye via AP)

Two phone messages left Saturday with the Lee County sheriff's office weren't immediately returned.

On Friday, a federal appeals court ordered a halt to construction of another section of the pipeline in North Dakota.

The pipeline, a project of the Dallas-based Energy Transfer Partners, has drawn widespread protests and several lawsuits.

Thousands of protesters have built an encampment in North Dakota in solidarity with the Standing Rock Sioux Tribe, which opposes the project.

The company has said it would generate an estimated $33.1 million US in sales tax revenue during construction and $27.4 million US in local property tax revenue during its first year of service. It also will require an estimated 4,000 local construction workers to complete the project.