In concrete-bottom stream culverts, water flows fast over the smooth bottom, making fish passage difficult or impossible. State transportation agencies are replacing these culverts with new, oversized ones. They're burying the inside bottom of the culvert below the streambed and creating a bottom with naturally occurring streambed materials. The New York State Department of Transportation has been using this technique on numerous trout-spawning tributaries to the Delaware River and its branches in the New York City watershed. For example, at Route 10 over Steele Brook in Delaware County, contractors buried the bottom of a culvert deep enough so the natural streambed materials wouldn't wash away in high water. Using small-sized construction equipment, they made a long-lasting new bottom with a thick layer of stockpiled cobbles and finer material. The new bottom has stayed intact, providing habitat for a variety of aquatic species and lowering water velocities so brook trout and other fish can swim through the culvert.
--Apr 25, 2003
|New York State Department of Transportat photo|
|Oversized culvert with natural bottom at Route 10 over Steele Brook|