Low spots in the yard can turn into a soggy mess after enduring spring rains. Not only do these depressions lead to muddy, damaged portions of lawn, but they also encourage mosquitoes and other pests in the yard. Fill large low spots by cutting pieces of sod away from the area using a spade. Set the pieces of turf aside and topsoil, bringing it level with the rest of the yard. Replace the grass and water it to conceal your work.