What is killing the grass?
Your problem is one that is affecting many yards throughout Michigan this spring: Voles. These tiny, voracious critters can eat a lot of stuff in the yard including grass plants and young tender bark off the bottoms of trees and bushes while the snow is piled really high. Those lines in your yard are their tunnels.
They go under the snow to avoid being eaten by hawks and owls that were also hungry this past winter.
You should be able to rake up the dead grass, and the grass should regenerate within a month or so. The voles just eat the tops of the grasses usually leaving the crown of the plants behind. If the yard is too badly damaged, you can reseed over the damaged areas successfully.
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