Consumer protection agencies are fielding complaints after a Minnesota fuel distributor provided diesel-tainted gasoline to outlets in southeast Minnesota, Wisconsin and Iowa.

Magellan Midstream Partners alerted the Minnesota Department of Commerce Saturday that small amounts of diesel had been added to gas distributed from its Rochester terminal that was delivered to 44 stations mostly between Rochester, Sparta, Wis., and Decorah, Iowa.

Ross Corson, director of communications for the Department of Commerce, said Magellan is in the process of replacing or diluting the contaminated fuel to acceptable standards. The department will be testing samples at Minnesota outlets to ensure the problem is corrected.

Corson said consumer protection agencies in Wisconsin and Iowa have also been alerted.

The contamination is not expected to cause long-term damage, according to the DOC, but could lead to poor vehicle performance. Customers affected can contact consumer protection agencies in the states where the gasoline was purchased.

Kwik Trip, which operates all but 11 of the affected stations, has replaced the bad gas and will compensate any customers affected, said company spokesman John McHugh.

The La Crosse-based chain had received two complaints by Monday afternoon.

McHugh said anyone who notices engine knock should have the problem checked out by a mechanic and file a claim on the Kwik Trip website.

“We would get it all taken care of and send Magellan a bill,” McHugh said. “They don’t have to wait for a response from a state agency.”