Raw steel production in the country's Great Lakes region shot up to about 676,000 tons in the week that ended Saturday, according to an American Iron and Steel Institute estimate.

Production rose by about 28,000 tons, or about 4.3 percent from the week prior. Most of the raw steel production in the Great Lakes region takes place in Indiana and the Chicago area. Production in the Southern District was estimated at 678,000 tons, up from 661,000 tons a week earlier.

Total domestic raw steel production last week was about 1.87 million tons, up from 1.85 million a week prior. Steelmakers made about 9.6 percent more steel last week than they did over the same period last year.

U.S. steel mills had a capacity utilization rate of 78.2 percent last week, which is up from 77.3 percent a week earlier. The capacity utilization rate had been 68.7 percent at the same time last year.

So far this year, domestic steel producers have had a capacity utilization rate of 77.2 percent, which is up from 76.8 percent during the same period in 2012.

Domestic mills have produced an estimated 74 million tons of steel this year, down 3 percent from the same period last year. The mills had made about 76.3 million tons of steel by Oct. 5, 2012.

Steel imports rose 13.9 percent in August over July. So far this year, total steel imports are 21.1 million tons, or about 9 percent less than during the same period in 2012. Reinforcing bars posted the biggest gain in August, increasing by 117 percent as compared to July.