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Smart Transportation Projects that Protect Fish Habitat

Bridges allow for more free flow of water. This enables roads to be built across waterways so people can get where they need to go while minimizing impacts on fish habitat in the waterway.  Photo credit: Chris Boelke, NOAA Fisheries

Culverts allow roads to be built over waterways, but they can change natural stream flow, altering fish habitats.  Photo credit: Jenna Pirrotta, NOAA Fisheries.

By Jenna Pirrotta, Integrated Statistics, contractor for NOAA Fisheries Greater Atlantic Regional Fisheries Office

Our nation’s roads and transportation infrastructure are important for getting people and goods where they need to go. A challenge in the northeast is navigating around the natural waterways – rivers, streams, estuaries and coastal bays that make up this region. Bridges and culverts, pipes carrying streams or drainage under roads, make navigating these waterways possible. However, they also pose a risk to the variety of valuable fresh, brackish or saline fish habitats such as saltmarsh wetlands, cobble, mudflats, or sandy substrates that are part of these waterways.

How transportation projects impact fish habitats

Bridges and culverts can affect fish habitats when they are newly installed, replaced, or repaired. The bottom habitats could be completely filled or removed when bridge support structures are placed or during excavation work. During project construction, sediments also can be stirred up that can irritate gills of fish or smother eggs.

Fish habitats can be temporarily impacted by loud noises from the driving of support piles. Loud noises and certain construction equipment and/or techniques may cause fish to avoid migrating through an area, preventing their access to spawning or feeding grounds.

What we’re doing to address these impacts

Certain work that occurs on bridges and culverts requires coordination with our offices to ensure that the work does not negatively impact fish habitats.  We review projects and provide conservation recommendations to minimize project impacts.

For instance, we may suggest the use of bridges instead of more constrictive culverts in a project. If culverts are too small or are not located properly in the riverbed, they can block water flow and make it harder for fish and other aquatic animals to move through them. We might also recommend that some of the work be conducted at a certain time of year when eggs and young fish would not be there, so nursery habitats are less likely to be impacted. Many times, we focus our recommendations on construction techniques, which minimize sedimentation, turbidity (suspension of material such as sand or gravel that decreases water clarity) and noise impacts.

We are currently working with the Federal Highway Administration to streamline and develop consistent guidelines to minimize environmental impacts and protect fish habitats. By closely coordinating and better understanding each other’s concerns, we hope to design transportation projects that protect and minimize impacts on fish habitats and make the permitting process faster and more predictable.