Correcting a drainage problem

This was before Christmas.  We have a terrible drainage problem at the cabin.  As you can see, there is a nice down slope toward the cabin.  It is about 20' to the left of where these guys are.  They're putting in a retaining wall/ water diverter.  When it rains, this is where it runs.  Then, it goes under the cabin and into the basement... causing all sorts of other problems.  We're hoping this will correct all that.