Arizona Sen. John McCain wants a subpoena issued immediately for the head of the Environmental Protection Agency to attend a hearing in his home state on the Colorado mine disaster the agency caused last year.

The August disaster caused an uncontrolled rupture of an abandoned gold mine that caused 3 million gallons of toxic sludge to spill into the Animas River, which sullied the waterways of three states.

"It's my understanding that the EPA has decided not to send a representative to this field hearing," the Arizona Republican said Wednesday, requesting that the chairman of the Senate Indian Affairs Committee issue a subpoena. "EPA's response is unacceptable. It's a violation of our obligation to protect the interests of Native Americans and their tribes and EPA must be present at this hearing."

"I respectfully request that the committee issue a subpoena for EPA Administrator Gina McCarthy to appear at the field hearing."

The hearing will be held on Earth Day, April 22, which is a big day for the EPA. McCarthy is expected to be part of President Obama's delegation to New York for a climate change meeting at the United Nations. Obama plans to sign a deal he agreed to in Paris to cut greenhouse gas emissions with nearly 200 other countries to fight global warming.

The field hearing will be held in Phoenix at the request of American Indian tribes affected by the toxic spill that crossed through Navajo land.

McCain said the Arizona hearing concerns "EPA's failing government-to-government relationship with Indian tribes."

Indian Affairs Committee Chairman John Barrasso, R-Wyo., agreed with McCain that EPA officials should attend and pledged to work with him on a subpoena.

The EPA said it would send testimony from a high-ranking agency official in lieu of an actual official attending.