Amazon is backing a large-scale watershed restoration project in California’s Upper Mokelumne River Basin, part of a broader effort to protect regional water supplies while reducing wildfire risk across the Sierra Nevada.   The project centers on 26,000 acres within the Eldorado National Forest, a key water source for communities in the East Bay. Restoration crews are expected to begin thinning overgrown vegetation and restoring native trees ahead of wildfire season this spring and summer. Project partners said the work could increase downstream water availability by more than 264 million gallons annually while helping protect vulnerable wildlife species, including the Sierra Nevada yellow-legged frog and California spotted owl.   Funding comes through a Forest Resilience Bond developed by Blue Forest and the World Resources Institute, combining public and private capital to finance restoration work that would otherwise move more slowly through traditional funding channels.…