The Dakota Access Pipeline has triggered protests since 2014 near the Standing Rock Indian Reservation in North Dakota, as well as in Iowa’s Quad-Cities area. Pam Mackey-Taylor, of the Iowa Sierra Club, says if the Iowa Supreme Court rules against landowners, it could allow corporations and others to use eminent domain for all sorts of reasons.

Last year a judge allowed oil to begin flowing in the pipeline but also ordered additional study because of concerns about the pipeline’s potential impact on tribal water rights. An environmental study by the U-S Army Corps of Engineers is due for release any day.