During the past 150 years, salmon and steelhead were blocked from habitat by dams and barriers at road crossings and elsewhere. In the past 20 years, more than 245 barriers have been removed, opening nearly 200 miles to salmon. More barrier removal projects are underway, including at the water storage dams in the Yakima basin. There have been major investments to restore flows in key tributaries in the Yakima basin and ensure that all water diversions are adequately screened so fish do not enter irrigation systems. Also, nearly 3,000 acres of salmon habitat have been protected and 135 miles of streams have been restored or protected. Restoring floodplains is another high priority in the Yakima and Klickitat basins. Projects to set back levees, reconnect side channels, and protect floodplain habitats are reducing flood hazards to local communities and providing valuable fish habitat.
Historic land uses reduced the region’s habitat quality in many streams, but most areas are recovering well as land managers protect habitat. The Department of Ecology’s invertebrate (bug count) data indicate that stream biological health in the region improved since 2011. However, more of the region’s salmon and trout habitat has sediment concentrations above what is good for those fish. Sediment concentrations increased from 53 percent of salmon and trout habitat in 2011 to 75 percent in 2015 (a drought year). More monitoring is needed to see whether these habitat data will show trends.
LARGE WOOD (VOLUME) – CLICK >> TO OPEN LEGEND
Most streams monitored by the Department of Ecology are found to have low amounts of wood when compared to relatively natural conditions.
Large wood, such as tree root wads and logs, creates places for fish to rest and hide from predators. It also slows 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, woody materials 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.
The Department of Ecology estimated in 2015 that 67 percent of the middle Columbia region’s stream kilometers had good biological health, a 15 percent improvement from 2011. More monitoring is needed to see if this is a trend.
The Department of Ecology estimated during 2015, that 75 percent of salmon and trout habitat in the middle Columbia region had excess sediment. This is 21 percent more habitat with too much sediment when compared to 2011. This increase in excess sediment happened in a period of drought. More than 18.5 percent sediment is considered too much for salmon and trout.
COPPER IN STREAM SEDIMENTS – CLICK >> TO OPEN LEGEND
Copper levels in the streams monitored by the Department of Ecology in this region appear to be low, which is good for salmon. Copper affects how fish smell to find food as well as sense danger. Consequently, fish exposed to high copper levels are more vulnerable to being eaten.
Department of Ecology data indicate that there is about 13-18 percent of the region with high levels of human disturbance in the riparian zone. This is a moderate amount compared to other areas of the state. More monitoring is needed to determine any trend.
Department of Ecology data suggest that the region has lost some riparian cover during a period of drought. More monitoring is necessary to see if this pattern persists and represents a trend. Trees and bushes along streams help shade the water, cooling it for fish. The plants also drop branches and leaves into the water, which provide food for the insects salmon eat and places for salmon to rest and hide from predators. Finally, the roots of the plants help keep the soil from entering the water and burying spawning gravel. Riparian cover in streams is needed for salmon growth and survival.