Farmers, towns and tribes slammed water-intake gates shut as a sludge-laden plume from a Colorado mine spill rolled down principal rivers in the desert Southwest on Monday, prompting local officials and families to demand answers about possible long-term threats from heavy metals borne along by the spill.

Colorado and New Mexico declared stretches of the Animas and San Juan rivers to be disaster areas as the orange-colored waste stream estimated to be 100 miles (161 million kilometers) long churned downstream toward Lake Powell in Utah after the spill Wednesday at the abandoned Gold King mine.

The Navajo Nation, which covers parts of New Mexico, Utah and Arizona, also declared an emergency as it shut down water intake systems and stopped diverting water from the San Juan River.

Members of the tribal council were frustrated during a special meeting Monday and echoed the sentiment of New Mexico officials that the federal government needs to be held accountable.

The 3 million gallons (11.36 million liters) of mine waste included high concentrations of arsenic, lead and other heavy metals. Workers with the U.S. Environmental Protection Agency accidentally unleashed the spill as federal and contract workers inspected the abandoned mine site near Silverton, Colorado.

The EPA has said the contaminants were rolling too fast to be an immediate health threat. Experts and federal environmental officials say they expect the massive river system to dilute the heavy metals before they pose a longer-term threat.

Dissolved iron in the waste turned the long plume an alarming orange yellow a look familiar to old-time miners who call it "yellow boy" so "the water appears worse aesthetically than it actually is, in terms of health," said Ron Cohen, a civil and environmental engineering professor at the Colorado School of Mines.

EPA officials said stretches of the rivers would be closed for drinking water, recreation and other uses at least through Aug. 17.

Tests show some of the metals have settled to the bottom and would dissolve only if conditions became acidic, which isn't likely, Cohen said.

The best course for the EPA would be to leave the metals where they settle, he said, noting that next spring's mountain snowmelt would help dilute the contaminants further and flush them downstream.

No die-off of wildlife along the river has yet been detected. Federal officials say all but one of a test batch of fingerling trout deliberately exposed to the water survived over the weekend. In addition, the Colorado-based Mountain Studies Institute environmental group saw no immediate unusual effects in flies exposed to the water, program director Aaron Kimple said.

As a precaution, state and federal officials along the river system have ordered public water systems to turn off intake valves as the plume passes. Boaters and fishing groups have been told to avoid affected stretches of the Animas and San Juan rivers, which are crowded with rafters and anglers in a normal summer.

Congress members, state officials and residents contend the EPA is not providing quick answers about long-term impacts from the spill.

"There are more people who want to know, 'OK, what's going to happen now? Are you going to fix this?'" said Michele Truby-Tillen, a spokeswoman for the San Juan County Office of Emergency Management in New Mexico. "'How are we going to protect our families? How long am I not going to be able to shower at my house?'"

In Cedar Hill, New Mexico, a family farm that serves as many as 3,000 customers in the Four Corners region, has been forced to stop irrigating dozens of acres of crops.

D'rese Sutherland of Sutherland Farmers said she received advanced warning from farmer friends in Colorado about the approaching plume.

"By the weekend, without any rain, we'll be in trouble," she said. "There's nothing we can do but wait and see what happens."

Members of New Mexico's congressional delegation sent a letter to EPA Administrator Gina McCarthy, expressing concern over the failure of the agency to notify New Mexico sooner about the problem.

They also asked that the federal agency develop a plan for dealing with the lack of water for communities in San Juan County and the Navajo Nation.

The EPA released a statement saying it was sharing information as quickly as possible with the public as its experts evaluate any effects of the spill.

Recreational businesses along the rivers said they were losing thousands of dollars.

"We had lots of trips booked. Right now we're just canceling by the day," said Drew Beezley, co-owner of 4 Corners Whitewater in Durango, Colorado.