Sediment Dam

Sediment Retention Structure
Toutle River Sediment Retention Structure

The North Fork Toutle River Sediment Retention Structure (more popularly known as the sediment dam) is more of a giant sieve than a true dam. It is designed to prevent volcanic sediment from being washed down the Toutle River, into the Cowlitz River, and thence into the Columbia River, which has to be kept open for ocean-going shipping.

This field trip takes in the view of the dam, and a one-mile walk to the top of the dam. Students will be learning about:

  1. The impact of volcanic sedimentation on the environment
  2. The engineering of the dam
  3. The flora of the woodland close to the dam

Directions: Drive East on State Highway 504 (Spirit Lake Highway) to milepost 20. Just after this, the SH504 Spur to the Sediment Dam is on the right. Turn down this road. After 1 mile, there is a parking lot on the right. There are no restrooms anymore at this venue.

Wear old clothes. Good walking boots, or waterproof boots may be necessary, as the area can be very muddy, if there has been recent rain.

For participation in this field trip, we invite a suggested donation of $15 per student (unlike the excursions, we will not charge for supervising parents, teachers or other adults, unless they are students). This donation amount includes educational worksheets, to put in a 3-ring binder (binder not included).