Put pine needles in a cocktail shaker. Using a muddler, pound until very fragrant. Add lemon slices and a handful of ice. Finely crush, cupping cocktail shaker with hand to keep ice from flying. Add Chartreuse, cover, and shake vigorously about 30 seconds.
Fill a rocks glass with ice. Strain cocktail into glass, top with sparkling water, and garnish with pine sprig.