DULUTH, MN (KDAL) - Now that the season for broken water mains and frozen water pipes is starting to wind down, warmer weather and melting snow is exposing another familiar problem for public works crews in Duluth, potholes. Several have opened up on streets across Duluth and Mayor Don Ness says it is a tough time of year to deal with them since the only patching material available now is what is called "cold mix". The mayor says crews will have to keep coming back and refilling the same holes over again until the more permanent "hot mix" is produced in mid May. The potholes get worse when warmer days are followed by freezing temperatures at night. The freeze-thaw cycle helps open small cracks in the blacktop into suspension jarring holes in the road.