Lasers used to renew Sound shoreline

The Army Corps of Engineers flew over Puget Sound yesterday, blasting away at the shoreline surrounding Skagit Bay with laser beams aimed at correcting decades of human environmental abuse.

Other areas scheduled next for the airborne laser assault -- a high-tech, landform mapping technology known as LIDAR -- include the shallow marine waters around Shilshole Bay in Seattle, Vashon Island and a section of Hood Canal.

"We're trying to map the areas that scientists believe are most critical for understanding the natural processes," said Bernie Hargrave, manager of the Army Corps' role in a multiagency effort aimed at improving the environmental health of the Puget Sound. The state's Department of Fish and Wildlife is also playing a leading role.

It's an ambitious effort, officially called the "Puget Sound Nearshore Ecosystem Restoration Project," that is likely to run into the billions of dollars and gain more public attention once it begins making remedial changes. A similar corps project in the Florida Everglades that has cost $8 billion has been criticized for making short-term fixes that ignored scientists' advice on how to make lasting ecosystem improvements.

Hargrave acknowledged that the corps is typically associated more with dams and roads -- and environmental disruption -- than with environmental restoration, but he said this project is a collaboration of many agencies that will be governed by the best science.

The goal for the Puget Sound project is to figure out how to restore much of the 2,300 miles of the marine shoreline to a more natural state. Getting a good map of the sea-floor bottom for the Sound's "nearshore" environment is part of a five-year, $12 million feasibility study under way aimed at determining what needs to be done and how.

Scientists with the U.S. Geological Survey who are experts at analyzing LIDAR data -- which they have been using to find hidden earthquake faults -- are assisting with the effort. The method requires firing laser bursts about 1,000 times per second from an airplane, detecting the bursts as they bounce back and performing computer analysis of these many millions of data points to create a precise topographic map of the sea floor.

"It's a lot more complex and difficult to do this through the water," USGS scientist Ralph Haugerud said. They need to use a more powerful laser that is split into a red and green light, Haugerud said, to both measure the water surface and the sea floor. Red laser light bounces off water; green can penetrate to about 80 feet.

The problem with the goal of restoring the shoreline to its natural state is that nobody really knows what "natural" means. With all the homes, bulkheads, piers, docks, waste streams, drained wetlands and developed estuaries, there just isn't that much natural shoreline left around Puget Sound.

"Ninety percent of what used to be here is gone," said David Montgomery, a University of Washington professor of earth sciences who studies what happens when water and land meet. Montgomery and his colleagues are assisting in the project by reviewing archived records and other data to better define the natural state.

LIDAR, a relatively new technology, has been used before in other parts of the world to map the sea-floor topography in shallow waters. But Haugerud hopes they can "push the envelope" in Puget Sound and use the technique to map eelgrass, kelp or even algae beds to provide more insight into the nearshore flora as well.