Residents of the Standing Rock Sioux Reservation are being asked to conserve water until a pump is repaired.

Ralph Walker, director of the Standing Rock Rural Water System, said residents have been asked not to use any water outside. The restriction has been in place for a couple of days.

The problem is not related to the water intake in Lake Oahe that became clogged with silt in November 2003 and left thousands of residents without water for several days. The water treatment plant is still able to get water from the intake and treat it, but one of two pumps used to get the water to a tower went down.

"It's not the intake, it's the actual plant itself," Walker said.

Walker said another pump is still providing the system with water, but the total capacity is cut in half, which is about equal to the amount of water needed in the winter.

The Environmental Protection Agencyhas been contacted by the tribe and it is keeping track of the situation.

Andrea Griese, an environmental engineer with the EPAin Denver, said the agency has been notified of the problem, but the tribe is still in full compliance with water quality rules.

"They are in full compliance because they have not lost any water pressure in the system,"Griese said.

Losing water pressure can create avenues for contamination, Griese said, which could require residents to boil water before drinking it. However, there has not been an order to boil water.

Officials hoped to fix the pump on Tuesday, but they weren't able to.

The pump was removed and taken to Fargo where the company, Watersmith, is working on it.

Walker said the pump will be returned on Monday.

Walker said the pump is scheduled to be replaced in August.

(Reach reporter Tom Rafferty at 223-8482 or tom.rafferty@;bismarcktribune.com.)