The reservoir and surrounding wetlands are rich in bird life, and are protected by the McArthur Lake Wildlife Management Area.

The fish ladder includes a sloping channel beside the spillway, with a series of low steps above it leading to the dam.

[8] Deep Creek rises east of White Mountain[a] and has a watershed area of about 480 square kilometres (190 sq mi).

Tributaries above the dam are used for spawning by wild adfluvial redband trout from Kootenay Lake, British Columbia.

The warm water of the reservoir may raise the mortality levels of juvenile fish migrating downstream.

[13] The McArthur Lake Wildlife Management Area covers 1,207 acres (488 ha), including the reservoir.

In the spring and fall it is a resting place for Canada geese, American wigeon, mallard, green-winged teal, lesser scaup, common goldeneye and bufflehead.