BISMARCK, N.D. (AP) — American Indian activist Chase Iron Eyes says he’s not deterred by a judge’s ruling that the developer of the Dakota Access pipeline can continue drilling under a Missouri River reservoir in North Dakota.

Iron Eyes is helping lead opposition to the pipeline, which would move North Dakota oil to Illinois. He says opponents will continue fighting the project in the courts and pushing for more environmental studies of the Lake Oahe crossing.

Federal Judge James Boasberg on Monday refused to halt construction while legal challenges by the Cheyenne River and Standing Rock Sioux are resolved. But he said he’ll more fully consider the request at a Feb. 27 hearing.

Iron Eyes says opponents will maintain an on-the-ground presence in the drilling area, “peacefully and prayerfully.”

There have been more than 700 arrests in the area since August.