HELENA - The Fort Belknap Indian reservation's tribal government must pay a $1,500 fine, bolster oversight of its utility, and follow a strict testing and monitoring regimen under a five-year plan meant to fix years of problems with its drinking water supply.

U.S. District Judge Dana Christensen on Monday approved the consent decree between the U.S. Department of Justice and the Gros Ventre and Assiniboine tribes of the Fort Belknap Reservation.

The deal has been in the works since 2009, with much of that time used to negotiate the amount of the fine the northern Montana tribal government should pay, according to Environmental Protection Agency attorney Amy Swanson.

The EPA said the tribal utility company had chronic violations in how it treated and monitored the reservation's drinking water supply for excessive bacteria, parasites and sediment that could pose a risk to human health.

Regulators issued corrective and emergency orders dating back to 2004, but many went ignored or unresolved, the Justice Department said in its complaint.

The violations cited by the EPA under the federal Safe Drinking Water Act could have amounted to tens of thousands of dollars per day for each day the violations were not fixed, but the tribal government cited financial hardship and applied for a lower fine.

"After a lengthy process of looking at any defendant's financial information, the United States ultimately decides whether or not (the defendant) has a legitimate ability to pay and what that amount is," Swanson said. "In this case, it was determined that (Fort Belknap) was able to pay a reduced penalty in the amount of $1,500."

Margaret Nicholson, director of the tribal-run Prairie Mountain Utilities, declined to comment on the agreement.

The EPA found violations with all five drinking-water systems on the reservation and an extensive history of system breakdowns. It said the tribes that govern the reservation failed to dedicate enough funding and staff to properly operate them.

The reservation's water supply repeatedly exceeded the allowable limits of contaminants, such as fecal matter that can contain the bacteria E. coli, and the utility did not adequately reduce and disinfect sediments that carry the risk of parasites such as Giardia and Cryptosporidium.

Swanson said the EPA has not received notice of anybody sickened by the drinking water.

The agreement will require the tribes to adequately staff the drinking water systems, pay in advance the cost of operating those systems each year, and follow a strict testing and reporting regimen.

The tribes also will hire a compliance officer to make sure the consent decree is being followed, Swanson said.

The agreement will be in effect for five years, after which the U.S. government can move to end it. The tribal government can request its termination after three years if it is meeting the requirements.