TUBA CITY, Ariz. (AP) – The Hopi Tribe has sued the federal government over its management of an open dump in Tuba City.

The lawsuit filed in tribal court alleges that the U.S. Bureau of Indian Affairs failed to ensure that waste at the 30-acre site did not contaminate the land or groundwater. The BIA operated the dump for nearly 50 years before it was closed in 1997, and part of it was covered up and fenced off.

A BIA spokeswoman did not immediately return messages left Tuesday seeking comment.

The lawsuit seeks enforcement of an order the tribe issued to the BIA in August demanding that the federal agency take immediate action to halt the spread of contamination.

The dump is on Hopi and Navajo land.