Description: Adult specimens are 26–48 inches in overall length, but rarely exceed 3 feet 3 inches. The males grow larger than the females. On the subject of scalation, one of the more distinctive characteristics of this subspecies is that it has three or more internasal scales – something that it has in common with C. viridis.

The color pattern usually consists of a buff, pale gray, pale brown, olive brown or yellowish brown ground color (hence the name, "lutosus," meaning "muddy"), overlaid with a series of 32-49 dorsal blotches. These blotches are dark brown to black in color, with pale centers and pale borders, and are often irregular in shape and wider than they are long. There is also a series of lateral blotches that are indistinct anteriorly, but become more distinct posteriorly and eventually merge with the dorsal blotches to form crossbands. Older specimens sometimes have a faded pattern, or they may have uniformly black blotches, with the dorsum of the head also being black.

Habitat: Inhabits the dry and barren areas of the Great Basin region, being found on hills, summits and old lake benches. They are said to prefer southern exposures among rocks and boulders on hillsides and buttes, low foothills, mountainsides, open deserts, alfalfa fields and valley floors.

Range: The United States in the Great Basin region. Its range includes Idaho south of lat. 44° North, Utah west of long. 111° West, Arizona west and north of the Colorado River as well as the north rim of the Grand Canyon, the entire state of Nevada (excluding Esmeralda, Nye and Clark counties), California east of the Sierra Nevada from Lower Klamath Lake south to below Lake Mono, Oregon south and east of the line Upper Klamath Lake–Fort Rock–Burns–Council (Idaho).

Found in these States: AZ | CA | ID | NV | OR | UT | WY

Venom: Rattlesnake bites can cause major, even fatal envenoming. All cases require urgent assessment and management. For larger species, about 20% will have an ineffective bite, with no local or systemic envenoming, so will not require antivenom and may not require prolonged observation. This figure will be higher for the smaller species, which are generally unlikely to cause a severe bite. All other cases, with any degree of local or systemic effects, require extended observation and may require IV antivenom (Crofab), the amount partly dictated by the severity grading. Beware fluid shifts causing shock, coagulopathy and bleeding, kidney damage and necrosis of the bitten area. Some subspecies have caused fatalities (Crotalus oreganus helleri).

Diet: C.o. lutosus feeds on amphibians, reptiles, birds, bird eggs, and mammals.

Reproduction: Young are born alive in broods of 3 to 13.

Status: The Great Basin rattlesnake is protected in Utah. Listed as Least Concern in view of its wide distribution, tolerance of a broad range of habitats, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Taxonomy: