Detroit will close nearly half of its parks and will reduce maintenance and services at dozens of others after the City Council passed on a deal that would have had the state operate the city’s Belle Isle park, Mayor Dave Bing said on Friday. Closing 50 of 107 parks will allow the city to keep running Belle Isle, a 985-acre park in the Detroit River, after the Council declined to vote on Gov. Rick Snyder’s proposal. Mr. Snyder’s offer called for the Michigan Department of Natural Resources to run Belle Isle as a state park, but for the city to retain ownership. The state would have taken on the $6.2 million annual operating costs.