Gov. Mark Dayton has told BNSF Railway's top executive that he is "deeply concerned" about the recent increase in Bakken oil trains on western suburban tracks into downtown Minneapolis, saying it puts an additional 99,000 people at risk.

In a letter to BNSF CEO Carl Ice released Wednesday, the governor asked the railroad not to operate oil trains on the line that passes Target Field when events are underway at the stadium, to extend first-responder training to all communities along the route and assess it for a worst-case accident.

BNSF, the major crude oil hauler out of North Dakota, recently disclosed in a mandatory report to the state that 11 to 23 crude oil trains per week are using the route from Willmar, Minn., through suburbs such as Wayzata and St. Louis Park into Minneapolis and across the Mississippi River at Nicollet Island. Dayton said he was concerned that BNSF did not inform him or his staff about the route change.

BNSF spokeswoman Amy McBeth said in an e-mail that BNSF will be talking directly with the governor about his concerns. She did not say whether BNSF will consider halting oil trains during Target Field events, but noted that crude oil has been shipped along the corridor at lower volumes.

"BNSF has multiple routes in the metro area that we utilize for hauling a variety of commodities," McBeth said. "Volumes and routes can fluctuate for a number of reasons. In all areas of the metro region where we move crude oil and other [hazardous material], we take a number of steps to reduce risk."

The railroad has said that major construction on rail lines across the state caused the shift in traffic to the new corridor. That work was expected to wind down as winter approached.

State Rep. Frank Hornstein, DFL-Minneapolis, said that during a game late in the Twins' season he saw three trains carrying either oil or ethanol pass Target Field over the course of six innings.

"We need to take steps to minimize public contact with these dangerous trains," Hornstein said.

Tracks under concession area

BNSF's line was moved away from the Target Field site during the stadium's construction, but trains still pass beneath concession areas and restrooms in the left-field corner near 5th Street. Closer to 7th Street, they pass beneath a back end promenade featuring an array of bike racks.

Twins spokesman Kevin Smith said Tuesday that no large events are planned at Target Field now that the baseball season is over. There are some small meetings, events and parties planned through the remainder of 2015.

"While our preference would be for less of this specific type of rail traffic through the ballpark corridor, we don't view it as a significant concern," Smith wrote in an e-mail.

Minneapolis isn't the only city with oil trains passing by stadiums. The Seattle City Council passed a resolution in July requesting, among other things, that BNSF not transport oil through the city during large events at Safeco Field and CenturyLink Field. Hornstein said the Minneapolis City Council is planning to discuss a similar resolution in November.

Hornstein criticized railroads for not disclosing their plans for worst-case oil train disasters and spill cleanup.

"The fact that they're continuing to route these trains through densely populated areas, near businesses and residences, stadiums, coupled with the fact that the railroads are not being forthcoming … is hugely problematic," Hornstein said. Dayton's letter also called on BNSF to verify that the same level of crude-by-rail inspections are being performed on the Willmar-to-Twin Cities route, issue a public statement about when the train traffic will return to normal "and keep as many oil trains as possible out of this area of concern."

Concern about oil trains

Crude-by-rail has faced new public opposition and regulatory scrutiny since the July 2013 oil train disaster in Lac-Mégantic, Quebec, killed 47 people. Since then, more than two dozen other oil train accidents have occurred in the United States and Canada, including two fiery North Dakota derailments with no deaths.

Oil trains haul nearly half of North Dakota's crude oil to coastal refineries. From January to mid-September, North Dakota loaded 466,745 barrels per day onto oil trains, according to Genscape, a Louisville-based energy intelligence service that monitors the traffic.

The uptick of Willmar-to-Twin Cities oil trains began in July, and accelerated in September, according to traffic reports obtained by the Star Tribune and reported in early October. Until this recent shift, most BNSF oil trains traveled from Moorhead to St. Cloud, and approached Minneapolis through Anoka and Coon Rapids.

Altogether, BNSF says 28 to 48 Bakken oil trains per week cross Minnesota. Canadian Pacific, another Bakken hauler, sends seven to 11 oil trains per week through the state, according to its filings. These all-tanker trains can be 100 cars long.

david.shaffer@startribune.com 612-673-7090 • Twitter: @ShafferStrib

eric.roper@startribune.com 612-673-1732 • Twitter: @Stribroper