Freeing the Elwha (Restoring the Elwha River)
OverviewThere are many important factors involved in removing the Elwha Dams and restoring the Elwha River. What strategies is Olympic National Park employing to help the river and its anadromous fish recover?
This lesson focuses on the plans to remove the dams, restore the river, and return salmon to the Elwha River watershed. Managers will have to use different strategies depending on the current population levels, life histories, and habitat requirements for each species of salmon, to ensure recovery. Some species will be able to naturally recolonize the river and return to anadromy. During the dam removal process, there is expected to be great amounts of sediment released from the deltas which have formed at the mouth of the reservoirs. To assure their survival, some salmonid species will be stored and propagated in hatcheries, protected from the high levels of suspended sediment. Some species will need to be out-planted up river to facilitate recolonization following dam removal. In addition, a great deal of ecological work will be necessary post dam removal to restore vegetation, engineer logjams, and return the sediment regime to form spawning beds.
- Hatchery- A facility used to rear juvenile fish for the purpose of stocking rivers or lakes, producing fish for commercial fishing activities, or restoring endangered fish populations.
- Exotic/Non-native- A species introduced to an area by humans either purposefully or accidentally that competes with native species, often with serious ecological consequences
- Course Woody Debris- Large woody structures such as logs, branches, and trunks that are left behind by stochastic events such as forest fires, wind storms, flooding, or logging activities.
- Logjam- An accumulation of large woody structures (mostly logs and branches) along a river's course from high water flows, which deflect or slow down water flows and create backwater pools or sediment accumulations for fish.
- Lesson 16- Restoring the River.pptx
- Stream table
- Reflection Journal pages (printable handout)
- Vocabulary Notes (printable handout)
Review Essential Question; introduce Guiding Question.
Students should take a few minutes to respond to the first reflection prompts. Discuss their answers and any questions they've generated.
Hand out the Vocabulary Notes. With this lesson you may want to define the words before presenting the PowerPoint Lesson.
Present the PowerPoint.
Present the animation of the Glines Canyon removal.
Do the stream table demo.
Hand out the second Reflection Journal Page. Give students time for a final reflection the lesson.
Another great animation
Course Woody Debris