Eagle Lake (Lassen County) - Watershed and Tributaries

Watershed and Tributaries

Eagle Lake was once part of a large lake on the Modoc Plateau millions of years ago. The modern lake is 24 km long by 3–4 km wide and is highly alkaline (pH 8-9). The lake consists of three basins, two of them averaging 5–6 m deep, the third averaging 10–20 m and reaching a depth of nearly 30 m.

The tributaries of Eagle Lake (beginning in the lake's north end and going clockwise) are Cleghorn Creek, Papoose Creek, Merrill Creek, and Pine Creek. Pine Creek is the main tributary of Eagle Lake and is 63 kilometres (39 mi) long. Now an intermittent stream; only the upper 11 kilometres (6.8 mi) of Pine Creek has perennial flow. In 1923 the Leon Bly Tunnel was constructed to export lake water to the Honey Lake Valley via Willow Creek, a tributary of the Susan River. The two mile long tunnel was cut through old lava flows but falling lake levels rendered it useless and a landslide partially blocked the tunnel entrance. However, a 1990 study found that lake water still flows through the tunnel although tunnel fish are from the Willow Creek assemblage.

• The lake just before dusk.

• The lake in the afternoon.