Scientists have discovered microplastics in Sierra snowpacks, raising concern that it maybe be contaminating the drinking water. A combination of sources is likely: wind may be sweeping the particles from the ocean to the clouds. Clothes dryers spew synthetic fibers like nylon and rayon into the air. A third possibility is that plastics enter the atmosphere as tarps, plastic water bottles and industrial paints disintegrate from exposure to the elements. Scientists at the Desert Research Institute in Reno are taking snow samples from across the mountain range to probe how microplastics get into snowflakes and, ultimately, California’s water supply.