Bear Lake Water Quality

Science Center Objects

Bear Lake, located approximately 50 kilometers (km) northeast of Logan, Utah, straddles the Utah-Idaho border and is nestled in a graben valley between the Bear Lake Plateau on the east and the Bear River Range on the west (Reheis and others, 2009). Its calcium carbonate type water is a brilliant green-blue color that, in combination with sandy beaches and easy access, draws thousands of visitors each year (Utah Division of Natural Resources, 2017). The lake is home to four endemic fish species including Bonneville Cisco, Bonneville Whitefish, Bear Lake Whitefish, and Bear Lake Sculpin; and a unique variation of the Bonneville Cutthroat Trout (Bear River Watershed Information System, 2017).

Technicians deploy water-quality instrumentation on Bear Lake platforms

Water-quality instrumentation is deployed on Bear Lake on floating platforms.

(Credit: Cory Angeroth, USGS. Public domain.)

For the last several thousand years, the sources of water to this relatively large lake (32 km long by 11 km wide by up to 60 meters deep) were localized inflow from springs and surface run-off of rain and snow (Gerner and Spangler, 2006).  During 1911-12, a connection between the Bear River, located approximately 10.5 km north, and Bear Lake was established so that the lake could be used as a water-storage reservoir (Gerner and Spangler, 2006). Bear River water is diverted at Stewart Dam, near Montpelier, Idaho, via the Rainbow Canal.  Rainbow canal empties into Mud Lake, a shallow lake separated from Bear Lake by a natural dike that is also part of the Bear Lake National Wildlife Refuge. This water can be diverted into Bear Lake or returned to the Bear River through a canal that connects Mud Lake with the Bear Lake Outlet Canal. Water from Bear Lake can be pumped by the Lifton pumping station through the outlet canal and into the Bear River. Water levels vary 1-2 meters with releases of storage water in the top portion of the lake; however, there is a proposal to increase the volume of Bear River water stored in Bear Lake (see discussion below).



Increased population and resource development near Bear Lake pose complex challenges for local governments, resource managers, and environmental quality agencies/groups that work to balance economic growth while maintaining Bear Lake’s water quality and water clarity. Population in the Bear River Basin is expected to increase significantly by 2050. Development within and near Garden City, Utah, is moving outward from the lakeshore and up the sides of the foothills. Second homes and summer cabins account for most of the growth (Bear River Watershed Information System, 2017). Increased development near the lake may add to sediment and nutrient loading via soil erosion and run-off from urban surfaces.

Sediment and nutrient loading via the Bear River diversion and erosion of banks along streams that feed directly to Bear Lake are subjects of ongoing concern (Bear River Watershed Information System, 2017; Gerner and Spangler, 2006). To help provide water for rapidly growing cities along the Wasatch Front, a proposal was recently published to increase the volume of Bear River water stored in Bear Lake, which adds to existing concerns about Bear River diversions into the lake (Salt Lake Tribune, April 19, 2017). Overlaying these issues are periods of drought, which in 2004 caused Bear Lake to reach its lowest level in 70 years (Bear River Watershed Information System, 2017).

Platform holds continuous water-quality instrumentation as it floats on calm water on a blue-bird day

Platform is anchored for the summer season.

Water quality monitoring at Bear Lake tends to be done on a seasonal or more sporadic basis, which makes it difficult to identify short and long term water quality changes related to the issues described above, and build a robust baseline dataset that will be necessary for assessing future impacts to the lake. In addition, there are few weather stations in the vicinity of Bear Lake, which makes it difficult to interpret physical and chemical water data (e.g., water temperature and dissolved oxygen variability in response to net short and longwave radiation) or to compute lake energy budgets that are needed for evaporation estimates. To enhance water quality and weather monitoring at Bear Lake and address concerns about lake water quality and water budgets, the USGS, in cooperation with several local and state organizations/agencies, proposes to install two automated water quality profiling and weather monitoring platforms. The objectives, benefits, and approach for operating these systems are provided below.


The primary objective of the monitoring is to quantify current water quality and weather conditions and build a robust baseline data set that can be used to assess future water quality changes.  A secondary objective is to assess spatial water quality, weather, and evaporation rate variability across the lake.  In addition to these objectives, data provided by the buoys will help quantify/assess the following issues at Bear Lake:

  • Water quality impacts related to annual diversion and withdrawal of Bear River water to and from Bear Lake;
  • Total algae concentration variability throughout the water column, which is fundamental to understanding primary productivity and nutrient cycling in the lake;
  • Water quality impacts related to annual run-off from near-by streams;
  • Spatial and temporal variability of limnology processes in Bear Lake (thermal stratification dynamics, oxic/anoxic boundary dynamics, annual turn-over, chemocline existence, etc.).

Relevance and Benefits

Monitoring Bear Lake’s water quality and refining its water budget, including quantifying lake evaporation rates, are fundamental to managing this resource during this dynamic period of increased population growth and potential alteration of lake management protocols. Automated water quality and weather monitoring systems will provide the needed data. The USGS has extensive experience operating these systems on Lake Mead, NV and AZ, for a project with similar objectives (the author of this proposal built and installed four similar systems on Lake Mead and developed operation and maintenance and data processing protocols to ensure data quality objectives were met). USGS has a vital interest in remaining at the forefront of this technology, both in terms of operation/maintenance of equipment and data interpretation.

The benefits of the project include

1) creation of a high quality, high frequency (i.e., short data logging intervals) water quality and weather dataset that can be used to assess variability of associated parameters around the lake;

2) dissemination of project data in near-real time to the USGS NWIS database, which is available to the public;

3) assessment of water quality impacts resulting from potential diversion of more Bear River water into Bear Lake than has been done historically;

4) detailed assessment of fundamental limnology processes such as annual turn-over and thermocline development at selected locations around the lake; and

5) refinement of Bear Lake’s water budget via well-documented estimates of evaporation.

Each of these benefits are timely and relevant to stakeholders, which is why several local and state organizations/agencies are project cooperators. The study will contribute to the USGS mission by increasing understanding of watershed and water quality interactions in large lakes in the intermountain west.



Bear Lake Water-Quality Data Visualization

Interactive color maps of water-quality parameters with depth over time can be accessed via the links below. When the water-quality platforms are on the lake during the spring, summer, and fall the maps are being updated manually on a weekly basis; more frequently when we are able. We are trying to resolve the daily auto-update feature issue and apologize for any inconvenience.


Current Season 

Past Seasons


Instructions for Interactive Color Map

  1. Select water-quality parameter via tabs at top of page.
  2. Select date range via time-slider tabs or directly by selecting begin and end dates at each end of time slider.
  3. Hover over any point in the color map to see date and time, depth, parameter value, and status of data.
Color visual map that shows changes in water quality with lake depth over time

This is a static image used to show features that can be manipulated by the viewer when using interactive color maps from links provided above.

Python script and Tableau visualization developed by Katherine K. Jones, USGS Office of Quality Assurance.