Pahsimeroi Fish Hatchery


Pahsimeroi Fish Hatchery is located in the Salmon-Challis National Forest about 20 miles north of Challis, Idaho.  It includes two separate facilities: the lower Pahsimeroi Fish Hatchery and the upper Pahsimeroi Fish Hatchery.  The lower hatchery is located along the Pahsimeroi River approximately one mile above its confluence with the main Salmon River near Ellis, Idaho. The upper hatchery is the main facility and is located along the Pahsimeroi River approximately eight miles upstream from the lower facility, just off of Dowton Lane in May, Idaho.  Pahsimeroi Fish Hatchery is owned and financed by Idaho Power Company, and operated and staffed by the Idaho Department of Fish and Game.

Site Overview

Pahsimeroi Fish Hatchery currently serves as a spawning facility for steelhead and as a spawning and rearing facility for summer Chinook salmon.

Built in 1967, the Pahsimeroi Fish Hatchery was the last hatchery constructed as part of Idaho Power’s mitigation program.  It originally served as an acclimation facility for steelhead that were reared at Idaho Power’s Niagara Springs Hatchery and eventually released into the Pahsimeroi River.  Its role was expanded in the early 1980s to include the annual production of one million summer Chinook salmon.

In 2007, Idaho Power completed a two-year renovation of the upper hatchery that included construction of a 16,000 square-foot hatchery building, two concrete rearing ponds and installation of three production wells.  The new hatchery building and production wells provide the ability to rear juvenile summer Chinook salmon on pathogen-free well water until they are transferred to the outdoor concrete rearing ponds for final rearing on river water.  This strategy reduces the incidence of Whirling Disease caused by parasites found in the Pahsimeroi River.


Visiting hours are 9 a.m. -- 4 p.m., Monday through Friday.  Tours are available for individuals or groups. The hatchery also gives tours to students and classes of all ages. If you have a large group of people, please provide advance notice by calling the hatchery at 208-876-4330.

Species Production

Summer Chinook Salmon - Adult summer Chinook salmon arrive at the hatchery trap from mid-June through September.  Enough adults are trapped and spawned to rear approximately one million summer Chinook smolts for release into the Pahsimeroi River each year.  Fish are removed from the trap and placed into holding ponds where they are held all summer to await spawning.  Spawning runs from late August to October 1.

Spawning occurs at the lower hatchery.  Eggs are transferred to the upper hatchery for incubation and rearing.  The incubation and rearing cycle takes 18 months.  The incubation period occurs from late August through January, and the rearing period is from February through March of the following year.  At this point, fish become smolts and are released from the rearing ponds into the Pahsimeroi River where they begin their migration to the Pacific Ocean.

Steelhead - Pahsimeroi Fish Hatchery traps and spawns enough adult steelhead to supply Idaho Power’s Niagara Springs Hatchery near Wendell, Idaho, with approximately 1.2 million eggs annually.  In addition, the hatchery produces around two million steelhead eggs for other non-Idaho Power programs around the state.  

Adult steelhead arrive at the lower hatchery trap from late February through mid-May.  After being processed from the trap, the fish are transferred to holding ponds to await spawning.  Spawning begins in late March and concludes around May 15.  Many of the adult steelhead returning from the ocean each year are donated to Native American tribes, charities and food banks.

Eggs collected during spawning are incubated at the upper hatchery and eventually transferred to other facilities.  Eggs for IPC production are shipped to Niagara Springs Hatchery in early May.  In April of the following year, fish have reached smolt size (approximately 8 inches) and are hauled in tankers back to the lower hatchery where they are released into the Pahsimeroi River to begin their 800-mile migration to the Pacific Ocean.

Steelhead Chinook Salmon
Learn more about these fish and others in our fish identification section.
71 Fish Hatchery Lane
May, ID 83253
(208) 876-4330

location map

aerial view of Pahsimeroi hatchery

hatchery worker

hatchery yard
Last Updated: September 30, 2014 
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