At least 16 miles of the Kalamazoo River system have been touched by crude oil in what could rank as the Midwest’s worst spill.

An unexplained rupture of an underground pipe south of Marshall has released more than 800,000 gallons of oil that has made its way to the river via Talmadge Creek.

Gov. Jennifer Granholm activated the Michigan’s Emergency Operations Center in Lansing to help coordinate state resources.

Granholm toured the area by helicopter Tuesday evening, then met with state and federal officials for a briefing. She said more resources should be devoted to cleaning up the spill.

“From my perspective, the response has been anemic,” she said.

Tuesday evening, a team of local, state and federal officials appeared with representatives of the Canadian energy company Enbridge to provide information about the spill, but key questions remain unanswered.

Among those is how long the pipeline, which carries crude from western Canada, had been losing oil before it was discovered. Enbridge officials said they responded immediately when sensors indicated a drop in pressure in the pipe Monday morning. Marshall Township residents initially reported a strong oil smell late Sunday evening.

Another issue is the extent of the contamination. Enbridge’s Stephen Wuori said late Tuesday the oil sheen and smell had reached as far west as Fort Custer State Park near Galesburg.