Bear Lake Features & History

Bear Lake is a large (28,200 ha), oligotrophic, freshwater lake with a maximum depth of 63 meters and lies on the border between Utah and Idaho (Figure 1). The lake is a natural feature on the landscape, but was altered for human use in the early 1900s. Utah Power and Light (UP&L) constructed a canal system and a pump station in 1917 to divert the Bear River into Bear Lake (Milligan and Davis 2011). The top three meters of Bear Lake (1802.80 – 1805.52 meters above sea level, masl) serve as water storage for irrigation and power generation (Milligan and Davis 2011). Over the past century, Bear Lake has experienced lake level reductions up to 6.59 meters (m) below the full pool elevation (Figure 2). The lake level declines correlate with the six significant droughts in Utah since 1898: 1898 – 1905 (pre-pump station, no maximum reduction data available), 1928 – 1936 (6.59 m below full pool), 1946 – 1964 (4.23 m below full pool), 1976 – 1979 (2.64 m below full pool), 1987 – 1992 (5.55 m below full pool), 1999 – 2004 (6.26 m below full pool), and the most recent drought cycle from 2012 – 2017 reduced lake level to 3.52m below full pool (Figure 2). These periods of drought left formerly submerged littoral habitat exposed along the shoreline of Bear Lake (Figure 3).