ANCHORAGE, Alaska (AP) — Alaska highway officials say access to the city at the end of the trans-Alaska pipeline will be closed indefinitely by avalanches.

Two major avalanches and other smaller snow slides are blocking the Richardson Highway into Valdez.

One large avalanche roughly 12 miles (19 kilometers) outside Valdez blocked the highway and the Lowe River. The avalanche dammed the river and created a lake up to a half-mile (kilometer) long that is preventing heavy equipment from clearing the snow.

Alaska Department of Transportation officials say crews can't work on the avalanche from the downstream side because it could release a surge of dangerous floodwater.

The avalanches have not affected the underground trans-Alaska pipeline, and Valdez remains accessible by water and air.