Idaho Power Company is required to provide facilities capable of producing and releasing three million spring chinook smolts annually at this hatchery. The majority of these fish are released directly into Rapid River. In most years between one hundred thousand and a million fish are transported to the Snake River and released below Hells Canyon Dam to mitigate for lost runs to streams in Oregon. The power company has also constructed a facility at Hells Canyon for trapping adult steelhead and salmon from the Snake River. Salmon from the Hells Canyon Trap are transported to Rapid River Hatchery for spawning and rearing.

The Rapid River hatchery is located beside a tributary of the Salmon River, near Riggins. The hatchery is the largest collection, spawning and rearing facility of spring chinook salmon in Idaho.

Rapid River Hatchery was constructed in 1964 by Idaho Power as part of its fish conservation program. With an annual production of 3 million young salmon, this hatchery helps to maintain runs of spring chinook salmon in both the Snake and Salmon Rivers. With funds provided by Idaho Power the hatchery is operated by the Idaho Department of Fish and Game.

All funding for this project is supplied by Idaho Power Company. The Federal Energy Regulatory Commission requires Idaho Power Company to mitigate for the loss of fish runs due to the construction of Oxbow, Brownlee, and Hells Canyon Dams. These dams were built without fish passage facilities and eliminated the runs of steelhead and salmon up the Snake River and it's tributaries. Idaho Power Company provided funds to build Rapid River Hatchery and transplant part of the salmon run here to mitigate for the lost fish runs.

Idaho Power Company is required to produce and release three million spring chinook smolts annually at the Rapid River hatchery. The majority of these fish are released directly into Rapid River. In most years between one hundred thousand and a million fish are transported to the Snake River and released below Hells Canyon Dam to mitigate for lost runs to streams in Oregon.

The power company has also constructed a facility at Hells Canyon for trapping adult steelhead and salmon from the Snake River. Salmon from the Hells Canyon Trap are transported to Rapid River Hatchery for spawning and rearing.

Adult salmon arrive at the Rapid River Trap (located about two miles downstream from the hatchery) from early May through August.

The fish arriving through mid-July are classified as spring-chinook and later arrivals are designated summer-chinook if they are not marked. These summer-chinook are released back into Rapid River to maintain a naturally reproducing population above the hatchery.

When adult fish enter the trap they are removed daily, checked for tags, and measured. Each fish receives an injection of antibiotic to prevent disease. The USDA prohibits distribution of these fish for human consumption after this treatment.

After processing at the trap the fish are transferred to holding ponds at the hatchery to await spawning. The fish begin to mature by mid-August and the females are sorted for ripeness and spawned. Each female produces 3,500 to 5,000 eggs. After spawning the eggs are placed into two buckets and fertilized with the sperm (milt) from two males. This improves genetic diversity and simulates wild conditions.

The fertilized eggs are taken to the incubation building where they are disinfected with iodine and placed in Heathstack type incubators. River water flows through the incubators during the entire incubation cycle, from fertilization to the swim-up fry stage (approximately one year). Click here for an explanation and pictures of the early stages of development.

The total number of eggs collected each year depends upon the number of returning females. This hatchery requires a return of 2,500 to 3,000 adults to produce enough eggs to meet release goals.

It takes about six weeks for the eyes of the embryonic fish to appear within the eggs. This is called "eye-up". Eggs can be handled after eye-up to allow removal of unviable eggs or segregation. The eggs will remain in the incubators until they hatch and develop enough to swim about and search of food.

For the earliest spawn this occurs in December and will continue through March for the latter egg takes. The total time needed for the eggs to hatch and for the fry to "swim-up" depends on water temperature. Water temperature is measured in units called DTUs or Daily Temperature Units.

Newly emerged fry are moved to the outdoor rearing ponds (raceways). The fry are then fed frozen food in the raceways until they are about 2 inches in length. In May they are each marked with an adipose fin clip to identify their hatchery origin. Coded-wire tags are imbedded in a percentage to provide more detailed information.

After marking the fingerlings are moved to the large rearing ponds. Each pond section can hold up to half a million fish. Feeding continues through the summer until winter water temperatures drop below 35o. As water temperature begins to increase in early spring feeding resumes until the fish are released during March and April. At the time of release a physiological change occurs (smolting) and the fish begin to show different behavior indicating their readiness to migrate the 600 miles to the Pacific Ocean.

The raceways are fed with flowing, river water that is not temperature controlled. The raceways also have natural, gravel and rock bottoms. These factors help the young fish adapt to more natural conditions, thereby increasing survivability when released to the wild.

From 1964 to the present, adult salmon returns to Rapid River Hatchery have varied from less than 200 to more than 17,000. Nature continues to be an important ingredient to successful migration and man made barriers pose a challenge to fish. Migration conditions as well as oceanic variables combine to influence the subsequent return of adult salmon to Idaho. Rapid River Hatchery has been rated one of the most successful in the Pacific Northwest. With the addition of fish produced at other facilities, and hopefully, an improvement in migration conditions along the lower Snake and Columbia Rivers, the salmon will again provide anglers in Idaho the chance to fish for these magnificent creatures.