To help struggling salmon populations, the state of Washington is legally required to replace hundreds of culverts that divert streams under roadways. The state transportation department is replacing old, rusting metal pipes with broad, concrete promenades that provide more gradual gradients and gentler flows for salmon swimming upstream to access more spawning grounds. The full scope of the effort will last 17 years and cost $3.8 billion.
Click here for original story, DNA shows where Washington culvert replacements helped spawning salmon
Source: Phys.org