Great Lakes and Great Times: Michigan boasts four Great Lakes, 11,000 inland lakes, 36,000 miles of rivers and streams, 20 million acres of forests, 100 state and national parks and recreation areas, 1,300 miles of bike trails, 6,500 miles of snowmobile trails, the second-most ski areas in the nation, 650 public golf courses, 600 campgrounds, and an international dark-sky park-just for starters. OSAs regularly perform professional occupational safety advisor assignments which are recognized by Civil Service as more complex than those assigned at the experienced level, i.e., occupational safety consultation and advice to construction industry businesses, unions, trade organizations, employee and employer associations, schools, colleges, municipalities, counties, and other state agencies in their assigned geographical area.