Students in all Eden Valley-Watkins schools will have to wait until Monday to return to school. Clean-up crews are mopping up a mercury spill after an old-fashioned barometer from a science class was dropped at Eden Valley Secondary School last Tuesday. It was only a quarter cup of mercury, but officials are still working to make sure the schools is clear of toxins. The Minnesota Pollution Control Agency (MPCA) has a program to help schools avoid this kind of problem called the Mercury Free Zone. MPR's Cathy Wurzer spoke with Sam Brungardt, a public information officer for the MPCA.