Becharof National Wildlife Refuge

Becharof National Wildlife Refuge on the Alaska Peninsula covers about 1.2 million acres and holds Becharof Lake, Alaska’s second-largest lake. The lake supports the world’s second-largest run of sockeye salmon and the largest concentration of brown bears in Alaska.[1]

The lake

Becharof Lake is 35 miles long, 15 miles wide and up to 600 feet deep, and is the largest lake in the National Wildlife Refuge System. It supplies about six million adult salmon a year to the Bristol Bay fishery.[1]

Setting

The refuge lies within the Aleutian Range, mainly in the Lake and Peninsula Borough, and had been a national monument from 1 December 1978 before becoming a refuge in 1980.[1]

Ukinrek Maars

The Ukinrek Maars are two craters within Becharof National Wildlife Refuge that formed in a phreatomagmatic eruption in March and April 1977, lasting about ten days, with no previous recorded eruption. The erupted magma was olivine basalt from the mantle. The western maar is elliptical, up to 170 meters across and 35 meters deep, and the eastern maar is circular, up to 300 meters across and 70 meters deep, with a 49-meter lava dome within its crater lake [2].

Location and significance

The maars lie on the Alaska Peninsula on the north side of the Aleutian Range, about 1.5 km south of Becharof Lake and about 12 km northwest of Peulik Volcano. They are a clear example of maar formation, and the name, given shortly after the 1977 eruption, translates roughly to two holes [2].

FAQs

How large is Becharof Lake? 300,000 acres.

What lives there? Sockeye salmon and brown bears.

Where is it administered? King Salmon.

When did the Ukinrek Maars form? In March and April 1977 [2].

Where are they? Within Becharof National Wildlife Refuge on the Alaska Peninsula [2].

Sources

1. Wikipedia: Becharof National Wildlife Refuge
2. Wikipedia: Ukinrek maars

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 12, 2026Researched and drafted with AI assistanceReport an issue