Habitat

Aerial view of the Tucannon River

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Habitat in the Snake River region

Fish passage, floodplain connectivity, and in-stream flow are the regional priorities

The region is removing barriers to fish migration, keeping water in streams, planting trees to shade and cool the water, and removing and setting back dikes to allow rivers to meander and connect with their floodplains. Recent accomplishments include the following:
Four projects will install tree root wads and log structures in the Tucannon River and Penawawa and Pataha Creeks to improve salmon habitat. On the Tucannon River, more than a mile of dike was set back. Fish passage has been restored at a dam in Asotin Creek and a fish-blocking pipe was removed on Steptoe Creek, opening 3.5 miles of habitat.

Problems for salmon: stream alterations result in warm, muddy, blocked, and low flows

Monitoring by the Department of Ecology shows that there is too much fine sediment in the streams studied in this region. Excess sediment was found in about 60 percent of the salmon streams studied. This causes problems for salmon including smothering fish eggs, changing the shape and route of the stream, and reducing stream capacity to hold floodwater or provide cover for fish.

Indicator data

Habitat Projects

What does this indicator mean?

Habitat Quality

What does this indicator mean?

LARGE WOOD (VOLUME) – CLICK >> TO OPEN LEGEND

Most stream sites sampled by the Department of Ecology in this region show low levels of wood volume when compared to natural conditions. This is true, even in this dry region, which may be naturally less conducive to tree growth. Large woody materials, such as tree root wads and logs, create places for fish to rest and hide from predators. They also slow the water, which reduces erosion and the amount of sediment in the streams. Slower water allows small gravels to settle to the bottom for spawning areas. Finally, they change the flow of the river, creating riffles and deep cold pools, giving fish more varied habitat. Projects that add large woody materials to streams can help to counteract the damage from human activities. Projects that protect or add trees along the sides of streams also can help in the longer term because the trees drop branches and leaves into the water, adding woody materials to the water.

 

There is too much sediment in the salmon and trout streams in this region. More than 18.5 percent of the stream bed is considered too much sediment for members of the salmon family.

 

The Department of Ecology estimates that this region has lost some riparian cover which provides streambank shade. In 2011, they estimated 75 percent of stream kilometers to have good riparian cover while in 2016 they estimated 52 percent. More monitoring is necessary to see if this pattern persists and represents a trend.

For more information about habitat project actions, visit the Recreation and Conservation Office’s Habitat Work Schedule and Project Search public databases.

Visit How we measure for background about this data, and our Salmon Data Portal for original source data behind the indicator charts and graphs used throughout this site.