DES MOINES — Opponents of an underground oil pipeline being constructed in Iowa delivered petitions to U.S. Department of Justice officials Wednesday bearing 33,000 signatures of people wanting President Obama and the U.S. Army Corps of Engineers to deny pending permits and halt the project.

“Make no mistake, this is far from over. We will stop this pipeline,” Kari Carney, executive director of 1000 Friends of Iowa, told about 100 members of the Bakken Pipeline Resistance Coalition, landowners and other Iowans who rallied at the banks of the Des Moines River before marching to the U.S. Courthouse to deliver the petitions. They also called on federal officials to investigate potential violations in the process.

Last week, three federal agencies announced they would temporarily maintain a halt on construction at one segment of the Dakota Access pipeline route that spans 1,134 miles from the Bakken oil fields in North Dakota through South Dakota and Iowa to a shipping hub in Illinois.

Standing in solidarity with the Standing Rock Sioux Tribe, which forced last week’s action in North Dakota, pipeline opponents in Iowa are demanding that Obama and the corps deny the pending permits, rescind existing permits, honor tribal land treaties and stop the Bakken pipeline.

“The entire process for approving this pipeline has been flawed from the beginning — from the Army corps’ failure to require an environmental impact statement to the Iowa Utilities Board allowing construction to begin before the company had its permits,” Carney said. “Our water, land and climate are being threatened and we need the president to step in and say no.”

Miriam Kashia, an Iowa City member of 100 Grannies for a Livable Future, said the pipeline is the product of a rigged process that granted illegal use of eminent domain authority “for out-of-state corporate profits,” Opponents said the project carries “enormous environment and economic risks” that threaten Iowa’s underground aquifers and waterways.

“At his very moment, Dakota Access is boring under the Des Moines and Mississippi rivers. The ramifications of an inevitable spill are unthinkable,” she said.

Last week, Iowa pipeline opponents who had written Obama seeking his intervention and an order requiring an environmental impact statement for the entire pipeline route expressed disappointment with the response from the president but vowed to press their demands.

In his letter, Obama noted that his administration has “made great strides” in confronting climate change and noted that the federal government has strengthening so-called fracking regulations to protect public and Native American lands.

Obama made no specific mention of the Dakota Access pipeline or of taking any steps to intervene in the project.

Dakota Access, a Texas-based company, has begun placing some of the 346 miles of pipeline scheduled to cross 18 Iowa counties from northwest to southeast. The $3.8 billion project, expected to be completed this year, will transport up to 570,000 barrels of crude oil daily from North Dakota's Bakken oil fields through Iowa to a distribution hub in Patoka, Ill.

Last month, 30 people were arrested at a construction staging area in Boone County as they protested the pipeline being built in Iowa. Also, a woman was arrested in Lee County for protesting the project and organizers say they expect more demonstrations to occur.

A protest is planned for Saturday. Workers are drilling underneath the Mississippi River between Sandusky and Montrose in southeast Iowa, organizers say.