BONNERS FERRY - Habitat restoration on the Kootenai River will take place under water this year instead of being visible like in previous years.

A pilot project aims to improve spawning substrate for Kootenai River white sturgeon.

Changing the river's flow regime hasn't improved spawning substrate. Therefore, the Kootenai Tribe of Idaho plans to address the lack of survival of sturgeon eggs and larvae by adding the needed substrate.

Sturgeon are known to spawn near Shorty's Island (upstream of Fleming Creek and downstream of the Kootenai National Wildlife Refuge) but the substrate is fine sediment not rocky substrate.

Since sturgeon are broadcast spawners, they swim over an area as they release eggs and sperm.

For survival, the eggs need to stick to rocks or gravel where the eggs and larvae are hidden from predators.

With a sandy river bottom, the shifting sediment can easily cover the eggs and suffocate them. The fine sediment historically was deposited on the floodplain during floods but with levees and dikes the fine sediment is now being deposited in the channel bed.

The Tribe hopes to address one of the bottlenecks of sturgeon recruitment by adding rocky substrate to two areas: the deep part of the channel next to Shorty's Island and near the mouth of Myrtle Creek.

The rocky substrate will vary in size from 2.5 inches to 20 inches to maximize the space between the rocks for larvae to hide after hatching, according Sue Ireland, Kootenai Tribe of Idaho Fish and Wildlife Department Director.

The one-acre project areas will test the sustainability and effectiveness of adding rocky substrate to a reach of river where sturgeon are known to spawn. Right now the sand covers the eggs, according to Ireland.

The Tribe worked closely with the Idaho Department of Fish and Game to identify areas where sturgeon are spawning, according to Ireland.

The addition of rocky substrate will occur between August and November 2014. The rocky substrate will be in place for the sturgeon to spawn in May and June 2015.

The Kootenai Tribe of Idaho is planning on working near Bonners Ferry in 2015 and 2016. Habitat restoration will be immediately upstream and downstream of the highway bridge.

Upstream of the bridge, the Bonners Ferry Island project will address vegetation on existing gravel bars and instream structures to improve the food web.

Downstream of the bridge on the straight stretch, instream structures will be added to create deep pools for sturgeon migration and resting.