import arcpy, sys, traceback
mxd = arcpy.mapping.MapDocument(r"G:\WIU\projects\Emerald_ash_borer\dispersal.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
f = open(r"G:\WIU\projects\Emerald_ash_borer\Layer_list.csv", "w")
f.write("Layers\n")
for lyr in arcpy.mapping.ListLayers(mxd, "*", df):
f.write("%s\n" %lyr)
f.close()