WASHINGTON — Senate Republicans vowed Tuesday to issue a subpoena to force the head of the Environmental Protection Agency to appear at a field hearing in Phoenix next week on a toxic mine spill that fouled rivers in three Western states and on lands belonging to two Native American tribes.

Wyoming Sen. John Barrasso said the Senate Indian Affairs Committee will vote Wednesday on a plan to subpoena EPA Administrator Gina McCarthy.

Barrasso chairs the Indian Affairs panel, which is conducting an April 22 hearing on the 3-million gallon spill at Colorado’s abandoned Gold King Mine. The Aug. 5 spill contaminated rivers in Colorado, New Mexico and Utah, as well as in the Navajo Nation and Southern Ute Reservation.

A federal investigation blamed the EPA, saying an agency cleanup crew rushed its work, failed to consider the complex engineering involved and ended up triggering the very blowout it hoped to avoid.

Barrasso said the EPA has been “reckless,” first in causing the spill and then in failing to address it.

“They took their eye off the ball,” Barrasso said of the EPA. “They caused this toxic spill and now they are still not focused on cleaning up the mess they caused.”

While the EPA has agreed to provide written testimony, the agency has said McCarthy will not attend the hearing, which is scheduled for Earth Day. An EPA spokeswoman said McCarthy testified before the Senate Indian Affairs and Environment committees on the spill last year.

Barrasso called the agency’s response another indication that the EPA “has grown too big, too arrogant, too irresponsible and too unaccountable” to the American people.

“On Earth Day, the EPA ought to be there to confess the failures of the (Obama) administration” to those affected by the spill and specify “what they are going to do to correct it,” Barrasso said.

Spokesman Melissa Harrison said the EPA recently announced it would spend $157,000 to help the Navajo Nation recover costs incurred during the response to the Gold King spill. The money is in addition to more than $1.1 million spent by the EPA in response costs for the Navajo immediately following the spill.

The EPA has awarded the Navajo more than $93 million in grants to develop environmental and infrastructure programs, Harrison said.