White Salmon public works crews will conduct a week of vegetation management beginning Monday.  Public Works will be clearing sidewalks of vegetation or parts of trees that overhang sidewalks and streets, aiming to ensure a safe environment for students to walk or bike to school by removing vegetation that impairs the full use of the sidewalk and street.   This includes improving the line of sight and pedestrian hazard trees, primarily on N. Main and NE Estes Avenues.   A space of fourteen feet above the street surface and eight feet above the sidewalk surface will be cleared by the city.  City officials say trees can cause problems with visibility and create a hazard for drivers.  However, with proper maintenance and pruning, the trees can be an asset to White Salmon, providing shade and beauty.