Geography of Bonneville County, Idaho

Bonneville County, located in the eastern part of the state of Idaho, is a region characterized by its diverse geography, rich history, and unique natural features. From its rugged mountains and winding rivers to its fertile valleys and vibrant communities, the county’s landscape is as varied as it is captivating. In this comprehensive overview, we will explore the geography, climate, rivers, lakes, and other notable features of Bonneville County.


According to Foodanddrinkjournal, Bonneville County covers an area of approximately 1,900 square miles in eastern Idaho, making it one of the larger counties in the state by land area. It is bordered by Jefferson County to the north, Bingham County to the south, Madison County to the east, and Teton County to the northeast. The county seat is located in the city of Idaho Falls, which is also the largest city in eastern Idaho.

The geography of Bonneville County is characterized by its diverse terrain, which includes rugged mountain ranges, fertile river valleys, and vast expanses of agricultural land. The region lies within the Rocky Mountains, a major mountain range that extends from Canada to New Mexico along the western edge of North America.

To the east of Bonneville County, the landscape rises into the Teton Range, a subrange of the Rocky Mountains known for its dramatic peaks, deep valleys, and pristine wilderness areas. To the west, the land gradually slopes downward into the Snake River Plain, a broad, flat valley that extends across much of southern Idaho.


Bonneville County experiences a semi-arid continental climate, with four distinct seasons characterized by hot, dry summers and cold, snowy winters. The region’s climate is influenced by its elevation, its inland location, and its proximity to the Rocky Mountains.

Summers in Bonneville County are typically warm and dry, with average high temperatures in the 80s Fahrenheit (around 27-32°C). The region receives the majority of its annual precipitation during the summer months, primarily in the form of afternoon thunderstorms that bring brief but intense rainfall.

Winters in Bonneville County are cold and snowy, with average high temperatures in the 30s and 40s Fahrenheit (around 0-7°C). The region experiences frequent snowfall during the winter months, particularly in December, January, and February, which can accumulate to significant depths in the mountains and foothills.

Spring and fall are transitional seasons, with gradually changing temperatures and fluctuating weather patterns. These seasons bring milder weather and occasional rainfall, making them ideal times to explore Bonneville County’s outdoor attractions and scenic landscapes.

Rivers and Lakes

Bonneville County is home to several rivers, creeks, and streams, which play important roles in both the region’s ecology and human activities such as irrigation, fishing, and recreation.

The most significant river in Bonneville County is the Snake River, which forms the county’s western border and serves as an important transportation route, as well as a source of water for irrigation, hydroelectric power generation, and wildlife habitat. The Snake River is known for its scenic beauty, diverse wildlife, and opportunities for boating, fishing, and other recreational activities.

Other significant rivers in Bonneville County include the South Fork of the Snake River, which flows through the southeastern part of the county, and the Henrys Fork of the Snake River, which forms part of the county’s northeastern border. These rivers and their tributaries provide habitat for various species of fish, birds, and other wildlife, as well as opportunities for outdoor recreation and scenic beauty.

Bonneville County also contains several lakes and reservoirs, including Ririe Reservoir, Palisades Reservoir, and American Falls Reservoir, which offer opportunities for fishing, boating, swimming, and picnicking. These water bodies provide additional recreational opportunities for residents and visitors alike, as well as important habitats for waterfowl and other wildlife.

Natural Attractions

In addition to its rivers and lakes, Bonneville County boasts several natural attractions that showcase the region’s beauty and outdoor recreational opportunities.

The Teton Range, located to the northeast of Bonneville County, is one of the county’s most iconic natural features. The range is home to several prominent peaks, including the Grand Teton, the second-highest peak in Wyoming, and offers opportunities for hiking, mountaineering, camping, and wildlife viewing.

Grand Teton National Park, located just across the border in Wyoming, is a popular destination for outdoor enthusiasts and nature lovers. The park is known for its stunning mountain scenery, pristine alpine lakes, and abundant wildlife, including grizzly bears, elk, and bison.


Bonneville County, Idaho, offers a diverse array of geographical features, including mountains, rivers, valleys, and lakes. The region’s semi-arid continental climate, natural beauty, and outdoor recreational opportunities make it a desirable destination for residents and visitors alike. Whether it’s exploring the Snake River, hiking in the Teton Range, or fishing in Ririe Reservoir, Bonneville County invites visitors to experience the best that eastern Idaho has to offer.