The Lahontan Basin is a large, closed hydrologic basin located in the western United States, primarily in Nevada and parts of California. It is named after Lake Lahontan, a prehistoric lake that existed during the last Ice Age. The basin is characterized by its arid climate and unique geological features, including mountain ranges and valleys. Today, the Lahontan Basin is home to several smaller lakes and rivers, including the Truckee River and Pyramid Lake. The area is significant for its diverse ecosystems and serves as a habitat for various wildlife species. It also plays a role in regional water management and recreation.