FAIRBANKS — The water utility in North Pole continues to test for contamination in the city water supply, the city services director said on Friday.

The city’s primary well remains in operation after test results were clean.

A secondary well was shut down after a trace amount of the chemical sulfolane was found in the water.

City Services Director Bill Butler said weekly testing on the primary well is being done as a precaution.

“It’s just so that we are well aware of the condition of the city’s water supply,” he said.

The testing will take place regularly during the next several weeks.

The water utility has about 525 residential and commercial customers, Butler said. Private wells in the city also are being tested, and some residents are being encouraged to drink bottled water.

Sulfolane is used to make fuel at the Flint Hill Resources refinery.

The chemical spill is believed to have happened before 2000, when the chemical was discovered in groundwater monitoring wells near the plant, according to the Alaska Department of Environmental Conservation.

The health effects of long-term exposure to trace amounts of sulfolane are not clear.

Laboratory animals exposed to high levels of the chemical have shown changes to organs, including the liver, and the nervous and immune systems, according to the DEC.

A town meeting is scheduled for 7 p.m. Monday at North Pole High School.