DETROIT — Michigan’s top environmental officer was by turns cooperative and confrontational with the U.S. Environmental Protection Agency in a letter pledging to work with the federal government to ensure the safety of Flint’s drinking water but challenging the legality and scope of some federal demands.

Michigan Department of Environmental Quality Director Keith Creagh wrote Friday in a letter to EPA Administrator Gina McCarthy that the state “is committed to working” with her department and Flint to deal with the city’s lead-contamination problem. But he said the state has “legal and factual concerns” with an EPA order a day earlier taking state and city officials to task for their efforts so far and requiring them to take specific actions.

Creagh said Michigan “has complied with every recent demand” of the EPA and that Thursday’s federal order “does not reference the tens of millions of dollars expended by … the state for water filters, drinking water, testing and medical services.”

“The order demands that the state take certain actions, but fails to note that many of those actions … have already been taken,” Creagh, who recently replaced an official who resigned over the water crisis, wrote in his required response to the EPA’s order.

Flint’s water became contaminated with lead when the city switched from the Detroit municipal system and began drawing from the Flint River in April 2014 to save the financially struggling city money. The water was not properly treated to keep lead from pipes from leaching into the supply. Some children’s blood has tested positive for lead, a potent neurotoxin linked to learning disabilities, lower IQ and behavioral problems.