Doolan Canyon in eastern Alameda County, northwest of Livermore, is traversed by Cottonwood Creek and is known for tufa deposits and alkaline water that create an unusual habitat. The area supports wildlife including loggerhead shrikes and is recognized as habitat for the endangered Alameda whip snake, the California red-legged frog, other special-status species, and rare alkali-soil plants. In recent years, its significance has centered on conservation. Plans announced by Livermore and Dublin in 2007 aimed to preserve the canyon, and in 2019 the protected valley expanded by 160 acres, underscoring its importance as a natural landscape and refuge for sensitive species.