Have you noticed how many dead trees there are around the lake? These are mostly oak trees with an insect that gets between the bark and the core after a trim or damage due to weather. These insects can kill an oak in a very short period of time. Trees are a great filter from runoff down a hill or slope. There are precautions you can take. Please refer to the links belows for more information.
http://web2.msue.msu.edu/Bulletins/Bulletin/PDF/Historical/finished_pubs/e2764/e2764-2001.PDF