Located in the remote northeastern corner of California at the juncture of the Sierra Nevada, Cascades, Great Basin, and volcanic Modoc Plateau, Eagle Lake Biological Field Station affords excellent opportunities to study California’s fourth largest lake. A Pleistocene remnant of the Lake Lahonton system, Eagle Lake covers 12,146 hectares (30,000 acres) and stretches for nearly 23 kilometers (14 miles). This clear and cold high-altitude lake consists of three interconnected and limnologically distinct basins, which support only five fish species, all native and thriving: tui chub, Tahoe sucker, speckled dace, Lahontan redside, and rainbow trout. The landscape around Eagle Lake, also available for study, is primarily volcanic, with basaltic flows, lava caves, and a nearby caldera. Diverse habitats on lava flats accessible from the field station include fir and pine forests, mixed conifers, juniper and sagebrush scrub, and mountain mahogany. There are also more localized assemblages of manzanita and ceanothus brushfields, riparian woodlands with cottonwoods and willows, wet meadows, and freshwater marshes. These pristine habitats support more than 70 mammal species, 180 bird species, and one of the largest breeding populations of western grebes in North America. Dirt roads leading to the reserve are rough and rocky; four-wheel drive may be necessary during the winter and spring.