Flooding has long been an issue along these lower six miles of the Tolt; many residences are at risk during even modest flood events. But also of concern is what is called channel migration, when the river changes course and cuts a new path, heedless, of course, of private property lines.
When Terry started, LiDAR – aerial imagery that uses laser to map river-basin topography – didn’t exist. Nor were GIS – Geographic Information Systems – or, for that matter, high-tech sonar-based river surveys in widespread use.
For a variety of organisms—including amphibians, birds, and plants—evolutionary adaptations to road effects can arise in just a few generations.
King County ecologists document species prior to river construction projects to plan for protection and relocation efforts, if necessary.