FARMINGTON, N.M.— A yellow sludge spilling from a shuttered gold mine into a southwestern Colorado river has reached northern New Mexico, a state official said Saturday.

The plume arrived in the city of Aztec on Friday night and Farmington on Saturday morning, San Juan County Emergency Management Director Don Cooper said.

Officials in both cities shut down the river’s access to water treatment plants and say the communities have a 90-day supply of water and other water sources to draw from.

“There’s not a lot we can do. We can keep people away (from the river) and keep testing,” Cooper said. “We still don’t know how bad it is.”

About 1 million gallons of wastewater from Colorado’s Gold King Mine began spilling into the Animas River on Wednesday when a cleanup crew supervised by the Environmental Protection Agency accidentally breached a debris dam that had formed inside the mine.

The mine has been inactive since 1923.

No health hazard has been detected, but tests were being analyzed. Federal officials say the spill contains heavy metals, including lead and arsenic.

In addition to New Mexico, wastewater from the mine was also moving toward Utah.

The Animas flows into the San Juan River in New Mexico, and the San Juan flows into Utah, where it joins the Colorado River in Lake Powell.

The spilled water also contained cadmium, aluminum, copper and calcium, but the concentrations were not yet known.