Avid hiker Alyssa Johnston was exploring a trail in the High Sierra when something in the distance caught her eye. She approached the bright colors and realized they were Mylar balloons — and did not belong in the wilderness. Mylar balloons, which have a metallic coating and are filled with helium, have become a concern for biologists and nature lovers, disrupting the enjoyment of outdoor spaces and posing harm to wildlife. Their ability to travel long distances in the air means they are polluting extremely remote areas, although responsible balloon shops are working to educate customers on safe disposal. Johnston has pulled balloons out of lakes numerous times. Often, she said, “they’ll just disintegrate and I’m just trying to pick up all the little pieces because it’s this beautiful, pristine lake and then now you have this ‘Happy Birthday’ balloon.”