Tryon Creek State Park Culvert Assessment Project

Portland State University Senior Capstone Project

What are culverts and the problems associated with them?

Culverts are tunnels that carry water from streams or other sources under roads and pathways. Due the notoriously wet climate of the Pacific Northwest and the natural landslide area around Tryon Creek, the amount of water being channeled through the park has caused some major erosion issues. During storms a large amount of water is collected in the surrounding neighborhoods and conveyed through culverts, ultimately making its way into the creek bed. The water cuts away the soil causing erosion known as undercutting. This can ultimately lead to trails collapsing or landslides that contaminate the creek.

2Culvert - 9Why are culvert assessments important?

When large amounts of soil are dumped into the creek it makes it very difficult for organisms in the creek to survive. Historically, Tryon Creek was an active salmon spawning stream. Due in part to the massive erosion depositing soil in the creek salmon have been unable to return. One of the ultimate goals of this project is to create and maintain a healthy ecosystem for salmon to spawn.

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The safety of the walkways and trails is a top priority to Tryon Creek Natural Area. If there is a significant amount of undercutting to the point that trails collapse, someone could get seriously injured. When this does happen, it is very costly for the park to rectify. New trails have to be made to defer the public from the dangerous area, and the existing trails need to be repaired ­ creating both an ecological and financial problem.

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How can I get involved?

Be on the lookout for culverts around the park. If you see any signs that a culvert may be compromised, such as steep ravines that lack vegetation or pooling water at the entrance to or exit of the culvert, alert a Tryon Creek staff member.

To help volunteer with the Friends of Tryon Creek and participate in culvert assessments within the park contact Lizzy Miskell (Lizzy@tryonfriends.org). The Friends of Tryon Creek will provide training and organize small groups of volunteers to collect data and prioritize the problematic culverts. The data you collect will be used to help inform the staff at Tryon Creek State Park which culverts need attention and which are in good condition.

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Other ways to help reduce water run­off at home

  1. Wash your car at a commercial car wash instead of on the street or in your driveway. If you do wash your car at home wash it on a lawn.
  2. Keep a garden with native shrubs and vegetation. These plants are better at absorbing water than exotic lawns, and native plants help create a habitat for wildlife!
  3. Consider creating a rain garden. For information on what a rain garden is and how to make one go to https://www.portlandoregon.gov/bes/article/188636
  4. Plant trees and preserve existing ones. The immense root system of trees is better than anything else at absorbing and storing water.
  5. Collect rainwater from your downspout during the rainy season and use it to water your plants during droughts.
  6. Line impermeable surfaces with gravel trenches. These slow water run­off and allow it time to seep into the ground.
  7. Reduce the amount of area taken up by impermeable surfaces on your property, such as patios, driveways and rooftops. Instead replace or cover these areas with vegetation, or replace concrete with pavers.