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Culvert Mapping

Eightmile River: Wild and Scenic Watershed

Bobbi DesRoche

on 8 December 2015

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Transcript of Culvert Mapping

Poorly designed road crossings in the Eightmile River Watershed
Well designed road crossings in the Eighmile River Watershed
Why we do it
During the summer of 2015 we assessed crossings throughout the
Eightmile River Watershed
What we did
Eightmile River Watershed Road Culvert Mapping
Whenever a river or stream is crossed by a road the natural environment is disturbed. The crossing can represent a possible barrier for both fish and wildlife movement. Poorly designed culverts can also block water flow during flood events.
We collected information that can be used to identify high priority bridges and culverts for retrofit and replacement.


Summer 2015
(Geographic Information Systems)was used to present this map layout. First a road layer was applied to the watershed, then a hydrography layer was added generating
294 points
that may have a possible culvert.
227 points
had data, we focused on the
67 data points
that had no data.
We followed the
North Atlantic Aquatic Connectivity Collaborative (NAACC)
protocol to identify culverts and bridges' characteristics.

By the end of the season we were proficient in collecting specific data on culverts and identifying barriers on fish and wildlife passage.
NAACC Data Sheets
What Happens Next
The data entered on the
website is displayed on a web map. It can be view and used by anyone.
This program helps the town or state come up with a plan for culverts that need to be prioritized for retrofit.
YouTube Video: News 8 chief photo journalist Kevyn Fowler captured a road collapsing in Freeport, Maine during a storm.
The culverts are in good condition, however fish passage is severely limited due to the rip-rap immediately upstream resulting in no surface water.
There is no dry passage through the pipe making it unsuitable for terrestrial wildlife to access the other side without having to cross the road.
Poorly designed road crossings
"Danger of a culvert crossing that is undersized during flood events"
Map of total road culverts estimated in Connecticut
Impacts of Poor Designed Culverts: Can lead to...
Fish being unable to move upstream during critical low-flow, low-oxygen periods.
Poorly aligned culverts which could cause culvert system failure.
Improperly sized culverts which restrict access to vital habitats, and can also increase the chances of a washout during a storm.
Wildlife loss and degradation of habitat and diversity.
Stream Crossing
This pipe is in poor condition; it has rusted through in places, and it has been dented on the sides making the inlet even smaller.
Pipe is too narrow limiting light source which can be a problem for fish movement since they orient by light.
A severe constriction is present as a result of the stream being much wider than the pipe.
Stones at inlet are a blockage to wildlife.
There is no dry passage for terrestrial wildlife.
Poorly designed road crossings
Crossing condition is good and alignment matches the natural stream, however there is a dam immediately upstream that creates a severe barrier to fish.
No dry passage making it unsuitable for terrestrial wildlife.
North Atlantic Aquatic Connectivity Collaborative
Well designed road crossings
Although this crossing shows some wear, it is still functional and not a critical culvert for retrofit or replacement .
The culvert is aligned with natural stream flow.
The bottom of the pipe is at stream grade and water in the pipe matches depth and velocity of the natural stream.
There are no physical barriers or internal features.
Overall a well designed culvert that presents a good fish passage, however not suitable for terrestrial wildlife as there is no dry passage.

In this picture we can see that the crossing is in relatively good condition.
The flow alignment of the natural stream are maintained.
There are no physical barriers preventing fish passage or obstructing water flow.
The crossing spans most of the natural channel.
Well designed road crossings
Overall the bridge is in good condition.
The culvert is aligned with natural stream flow.
The bridge spans the full natural channel and includes some dry passage along the bank.
The stream bed is preserved allowing the water depth and velocity to match the natural stream.
In the past, culverts were designed with an objective of moving water efficiently across the road, with little consideration for fish and wildlife passage.
Full transcript