culvert

While councils had spent heavily to repair and upgrade infrastructure in the wake of recent storms, the report found there were still issues with culverts in many places.

The study, published Thursday in the journal Science, tracked air pollution emanating from a foamy, churning section of the river where water falls from culverts.

The once-abundant fish disappeared after the concrete culvert, installed in 1952 to support the highway, blocked their ability to migrate between fresh- and saltwater.

For example, these forces have prompted cougars to adapt by becoming more nocturnal, using culverts or taking riskier crossings across fragmented landscapes.

Before the rain, workers found more than 20 locations along Topanga Canyon Boulevard that required debris flow barriers and culvert replacements, along with other safety measures like rockfall cable mesh.