Mann Lake is an irrigation reservoir built in the early 1900s. It is owned and operated by the Lewiston Orchards Irrigation District, and is managed through a cooperative agreement with Idaho Dept. of Fish and Game as a popular fishing destination (focus is on planted Rainbow Trout).

Ornithological Summary

The reservoir provides a mudflat habitat, which draws rare/uncommon Idaho birds. Say's Phoebes, Ross's/Snow Geese, Common Loons, 6 species of Grebes, 7 species of Sandpipers, Killdeer, American Avocet, Greater/Lesser Yellowlegs, Wilson's/Northern Phalaropes, Dowitchers, Curlews, Willets, Dunlin, Marbled Godwits, and 6 species of Swallows are just some of the varied bird life observed here.

There is a large migratory shorebird population in the fall (July-September), including Western Sandpiper, Semipalmated Plover, Black-bellied Plover, Killdeer, American Avocet, Greater and Lesser Yellowlegs, Spotted Sandpiper, Semipalmated Sandpiper, Least Sandpiper, Baird?s Sandpiper, Stilt Sandpiper, Long-billed Dowitcher, and Wilson?s Phalarope. In spring and summer waterbird species include Western Grebe, Double-crested Cormorant, Great Blue Heron, Great Egret, gulls, Common Loon, American Coot, as well as multiple waterfowl species (including Snow Goose and Greater White-fronted Goose).

Mann Lake is also a vagrant trap. Rare species noted here include Ross? Goose, Clark?s Grebe, White-faced Ibis, Trumpeter Swan, Eurasian Wigeon, Long-tailed Duck, Red-breasted Merganser, Snowy Owl, American Golden-plover, Snowy Plover, Black-necked Stilt, Upland Sandpiper, Marbled Godwit, Red Phalarope, and American Tree Sparrow.

Conservation Issues

Excessive drawdown as a result of a severe drought in the early 1990?s allowed shoreline shrubs, in particular willows, to become established. This has reduced the area of the mudflats to migrating shorebirds and loafing waterfowl. To combat this problem, the Lewiston Orchards Irrigation District regularly scalps the shoreline with heavy equipment, thus preventing afforestation on approximately 20 % of the shoreline.


Owned by the Lewiston Irrigation District


The reservoir has mudflats, willow areas in addition to nearby fields.

Land Use

The main use of this site is water supply. But it is also a very popular fishing spot, and it supports a model plane club. Birdwatchers come here in the fall to watch the shorebird migration.

Stay abreast of Audubon

Our email newsletter shares the latest programs and initiatives.