The Puyallup and Muckleshoot tribes and the South Puget Sound Enhancement Group are using Light Detection and Ranging (LIDAR) based maps to track the effectiveness of a salmon habitat restoration project completed in phases between 2010 and 2014 on the Greenwater River.
“These maps are much more precise than traditional topographic maps,” said Russ Ladley, natural resources director for the Puyallup Tribe. “They can track landscape changes within less than a foot.”
Researchers use LIDAR to create topographic maps by shooting a laser at the ground from an airplane or drone. They can see small variations in the landscape because of differences in return times and wavelengths of the laser.
In addition to constructing 17 logjams, the partners also removed almost a mile of road, allowing the river to use more of its historic floodplain.
“One of the most important things we expected to see was a combination of a wider floodplain paired with reduced velocities in the river’s flow,” said Lance Winecka, executive director of the enhancement group.
Spring chinook, which lay their eggs in September before the first fall floods, will benefit in particular from a slower river.
“Those first harsh fall floods come when spring chinook eggs are the most vulnerable,” said Martin Fox, habitat biologist for the Muckleshoot Tribe. “Slowing the river by giving it more room to move as well as adding wood to add channel complexity means those eggs have a better chance to survive.”
Before restoration, there was a 7-foot elevation difference between the river and a historic channel on its north side. According to the new LIDAR maps, the river already is reoccupying the old channel at moderate flood levels.
The new logjams also are vital for salmon because they provide shelter and places for juvenile salmon to eat.
“Restoring historical habitat function and conditions is the most important thing we can do to improve salmon runs,” Ladley said. “This data is showing us positive indications of change and that our past efforts are bringing about the desired floodplain response. These, in turn, are resulting in greater resiliency to damaging floods, and improved fish production. The past three returns of spring chinook to the upper White are the largest ever recorded and it’s difficult to argue with that kind of success. Food and shelter are all things we can reverse if we work hard enough.”
Restored salmon habitat means the Greenwater River will flood in a more fish-friendly manner. Photo:
Brian Zierdt, SPSSEG