Why can’t you float the Boise River yet? Take it up with Idaho’s salmon

The Boise River is still flowing too swiftly to open float season, and it’s not just because of snowmelt and runoff.

After a record-low snowpack this winter, the Bureau of Reclamation is releasing water to help with fish migration.

Salmon and steelhead, a form of rainbow trout, are anadromous fish, meaning they are born in freshwater, spend most of their life in the ocean, and then return to freshwater to reproduce.

Idaho salmon in particular undertake one of the most difficult migrations in the country to spawn. They travel up to 900 miles from the Pacific Ocean to return to the exact freshwater rivers and streams where they were born. This journey requires them to climb fish ladders over dams, navigate culverts diverting streams under roads, and ascend up to elevations of 7,000 feet.

The journey is so difficult that salmon die after spawning, a phenomenon known as semelparity.

NOAA emphasizes that low water levels can block the migration path, and rising water temperatures make the journey more difficult for salmon accustomed to the brisk waters of the Pacific Ocean.

“We have such a unique watershed here where the cold water from the Sawtooths that runs through Boise is really helpful to send downstream into the warmer water bodies to facilitate fish migration,” said Scott Koberg, director of Ada County Parks and Waterways, at a budget presentation Monday.

Koberg explained that the ideal flow rate for float season is around 1,300 cubic feet per second, but because of water release throughout the Boise River Reservoir System to help fish migration, the current flow is around 2,000 cfs.

“These flows are specifically used to support out-migrating smolts, downstream through the lower Snake and Columbia rivers,” Marc Ayalin, spokesperson for the Bureau of Reclamation, told the Idaho Statesman.

These smolts are juvenile salmon and steelhead, usually no longer than 6 inches, making their way to the ocean. Their bodies will undergo changes along the way to prepare them for life in saltwater.

Monitoring water levels and augmenting river flow to ensure that they make it to the Pacific is imperative for the survival of the species.

When will the float season officially begin?

Last year the Boise River float season started on June 20, which is actually about a week earlier than normal, according to previous Statesman reporting.

As salmon and steelhead migration quota are reached, water releases will be decreased throughout the second half of June, according to Ayalin.

At the Ada County budget presentation, Koberg reminded people that even as river flow decreases, officials will be waiting on warmer temperatures and debris mitigation before the float season is underway. And the hot weather is coming — starting Friday, highs are basically in the 80s and 90s for as far as the forecasts can see.

Bonnie Shelton, spokesperson for Boise Parks and Recreation, told the Statesman that the Boise Fire Department still needs to finish its annual work of clearing trees and debris along the 6-mile route between Barber Park and Ann Morrison Park.

You can still float on the Boise River outside of the official season, but you won’t have access to Ada County services like tube rentals and shuttles, and authorities urge using extreme caution when the river isn’t “open” — and even when it is.

Keep an eye on the Float the Boise website for updates and current conditions.