DES MOINES, Iowa (AP) — Landowners have filed two lawsuits in northwest Iowa in an attempt to block construction of a $3.8 billion oil pipeline.

The landowners are trying to keep the pipeline company from being able to use eminent domain powers to secure access to their land for the project, the Des Moines Register reports.

Houston-based Dakota Access LLC wants to build the pipeline from northwest North Dakota to a storage facility in south-central Illinois.

Construction has begun in North Dakota, South Dakota and Illinois, but the Iowa Utilities Board has not authorized work to begin. And the U.S. Army Corps of Engineers hasn’t yet issued permits for the project.

Dakota Access officials have said the company will work with regulators to move forward with construction of the pipeline in Iowa.