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A Light Experiment for Habitat Enhancement

First steel framing installed by SDOT crews

SDOT crews are working to install three “light penetrating surfaces” as a pilot study for the future waterfront at Pier 62/63. Beginning the week of October 22, SDOT began installations to study how steel grating, glass planks, and a light tube will allow light to pass the pier to the waters below. Along the Elliott Bay seawall, overwater structures such as piers obstruct natural light from entering the nearshore environment. Some 60 percent of our urban waterfront is covered by piers and other structures, inhibiting plant growth and stalling juvenile salmon migration. These surfaces will be compared to understand their effectiveness at transmitting light, and could help increase the amount of natural light reaching the water of Elliott Bay, which is an important part of a healthy ecosystem.

The University of Washington’s Wetland Ecosystem Team (School of Aquatic and Fisheries Sciences) has partnered with the City of Seattle to help this research by:

Glass block set in place

  • Evaluating how much light reaches the water, at the surface and below.
  • Seeing the amount of light transmitted based on time of day and time of year.
  • Observing algae and plant growth beneath each surface.
  • Understanding fish responses to enhanced light conditions under dark piers.

Light penetrating surfaces are envisioned within cantilevered sidewalks of the new Elliott Bay seawall to help transmit light along the waterfront. The study is sponsored by the project as part of a habitat restoration element, which includes improvements for juvenile salmon which travel up the project area, and need light for spatial orientation, prey capture, schooling, predator avoidance, and navigation. Light conditions also influence the migratory patterns and behaviors of juvenile salmon.

Take a walk to Pier 62/63 to see these light penetrating surfaces in action! The project team would love to hear your feedback. Do you like the look of one type over another? Is one easier to walk on or around? What questions do you have?

For more information about the project, please visit: