Landscapes
Western lake - catchment systems, Bear Lake
Bear Lake basin is important to land managers because it supports extensive irrigation, flood control, a local fishing industry, and recreation. Water resources are being depleted because of climate dynamics and human activity. As water use in the area has changed, some of the habitats in the area have become stressed. It is important to understand the natural climate variability of the region in order to determine how much of the current change in water resources and environment is caused by natural variability and how much is caused by human activity.
By studying sediment cores, USGS researchers are piecing together environmental records of the Bear Lake region on relatively long-term (about 240,000 years) and recent (from the late 1800s to the present, corresponding with settlement of the area) scales to determine the impacts that human development has had on the region. Around 1912, Bear River water was diverted into Bear Lake, which led to changes in lake-water chemistry and sediment load. The clear turquoise water, for which the lake is renowned, was threatened. Canals were constructed to divert Bear River flow into the Bear Lake National Wildlife Refuge, where the water is allowed to flood the wetlands. This allows most of the sediment to drop out in the wetlands. The result is that the water is much clearer when it enters the lake than it would be if it flowed directly into the lake.
Photograph of two core segments from the Bear Lake National Wildlife Refuge. The core was taken near the Rainbow canal and shows older organic-rich marsh sediments underlying spoil from digging of the canal. The spoil is in turn overlain by over 70 cm of sediment and soil deposited during the last 90 years. Material is being prepared for dating of the older marsh sediment.
What is the impact of allowing river water to flood the Bear Lake National Wildlife Refuge?
The practice of letting river water flood the wetlands of the wildlife refuge is thought to be endangering the wetlands. Sediment in the river water is filling in the wetlands, resulting in a loss of this habitat.
USGS scientists are working with the wildlife refuge to better determine the effects of flooding the refuge. Our scientists are studying sediment cores taken from Bear Lake and the wildlife refuge and will provide the refuge with information derived from the study that has bearing on sedimentation in the refuge.
