All Things Maine
All Things Maine

Sunday, July 16, 2006

Culverts Are the Culprits

Ken Allen has an interesting piece at MaineToday.com about the problems culverts pose to Maine's brook trout.
In the 1990s and 2000s, another culvert problem has escalated. Using corrugated metal tubes to replace wooden bridges picked up momentum in the 1950s and 1960s, and decades later, they have rusted. Road crews have come up with a less expensive repair that involves slipping a plastic tube inside the culvert. This alleviates the problem of replacing them, which disrupts traffic and costs more money than liners.

These slip liners might seem innocuous, but they speed up the velocity of water rushing through the culvert because 1) they constrict the flow into a smaller diameter and 2) the smooth plastic allows the water to move faster than a corrugated metal surface does. Tiny brookies cannot move upstream against the faster current. [Link]

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