Strolling on the Lake of the Sky Trail, U.S. Forest Service officer Daniel Cressy marveled at the wildlife that first attracted him to Lake Tahoe. A bald eagle nestled into the top of a Jeffrey Pine looking out over the shimmering blue of North America’s largest alpine lake, and rising in the distance was Mount Tallac, a 9,739-foot peak that he’s skied many times. Then, along the path, Cressy spotted a tree with “J&B” carved into its trunk. … That small stain of civilization epitomized the growing tension between the millions of tourists who provide economic sustenance to the High Sierra paradise and the effort to preserve the natural splendor that draws them, a clash that came into sharp focus this week with a weeklong visit from world’s most powerful tourist, President Joe Biden.