Bothin Marsh is a 106-acre wetland in Marin County at the north arm of Richardson Bay, fed by Arroyo Corte Madera del Presidio and forming part of a larger bayside preserve. Long an estuarine environment, it likely provided resources for Native Americans. In the early 1970s, preservation efforts led by Jo Julin prevented developers from draining it for construction. Today the marsh is important habitat on the Pacific Flyway, supporting hundreds of native bird and wildlife species, including the endangered salt marsh harvest mouse and Ridgway's rail, and serving migratory birds. Its future is threatened by rising sea levels, prompting adaptation plans for trails, channels, and marsh restoration.