A bipartisan group of Western senators is seeking to hold the Environmental Protection Agency accountable for the financial harm it caused last year by spilling millions of gallons of toxic wastewater from the Gold King Mine in Silverton, Colo.

The lawmakers introduced an amendment Monday to a massive water infrastructure bill being considered on the Senate floor. The spill measure would address all outstanding costs associated with the 3-million-gallon spill that sullied the waterways of three western states.

"The EPA is responsible for the Gold King Mine spill, and therefore I'll fight to hold the agency fully liable and to the same standard as a private company," said Sen. Cory Gardner, R-Colo., the lead sponsor of the amendment. "It is unacceptable the EPA has not fully reimbursed all costs associated with the spill and that's why I authored an amendment to the Water Resources Development Act that requires the EPA to expeditiously pay out all states, tribes and individuals for emergency action in response to the spill."

In addition to addressing the costs of the mine spill, the amendment would direct the EPA to work with the affected states, tribes and local governments to develop a "long-tem water quality monitoring program of the rivers contaminated by the spill."

The amendment was introduced by Gardner, Republican Sens. Orrin Hatch of Utah and John McCain of Arizona, and Democratic Sens. Tom Udall of New Mexico, Michael Bennet of Colorado and Martin Heinrich of Nevada.

The amendment was introduced to the Water Resources Development Act, a massive bill for water-related infrastructure projects. Lawmakers are also looking to negotiate a deal in the bill that would include funds to address lead contamination in the water supply of Flint, Mich., which became a highly publicized scandal earlier in the year.

The EPA admitted to holding back information after it knew about the public health threat to the city's drinking water, which was caused when a city manager appointed by the governor diverted the town's water supply from the Great Lakes to the polluted Flint River. A senior regional EPA official resigned as a result.

The Gold King Mine disaster also captured the national stage as a disaster caused by EPA contractors. The Navajo Nation sued the agency last month for the harm the spill caused to the tribe's crops, the centerpiece of its economy.