Washout: The Destructive Power of a Burst Beaver Dam

Sometime in early July, a beaver dam burst in the Petawawa Research Forest. The resulting torrent of water destroyed several smaller beaver dams downstream and washed out two minor roads before washing out Clouthier Road, the main access road to the Petawawa Research Forest.

2008 July 18

It was a wet day last Friday (July 18), so rather than paddle in the rain, I chose to go for a drive in the rain and ended up at the Visitor Centre of the Petawawa Research Forest. We had noticed a few days earlier that Clouthier Road was closed, and a sign on the barrier indicated a washout. Curious, I investigated on foot, and found that a large piece of the road had been washed away. I am familiar with the innocuous little creek that was obviously responsible, and followed it upstream to determine the cause. It seemed most likely that a beaver dam had let go. I found that "Forestry" Roads R8 and R9 had been washed out and that the beaver pond east of Meridian Road and south of R1 had drained, but there was no sign of any flood damage upstream of that pond. Because it was raining, I didn't take that many photos, but Diana and I returned on Sunday to document the destruction more completely.

A satellite image of the area appears at the bottom of this page.

[Subsequent to publishing this page, I have been provided with a set of photos of the road during the washout taken by Renata Boulanger of Chalk River. The photos have been appended below.]

washout on Clouthier Road in Petawawa Research Forest

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Diana photographing the washout on Clouthier Road in the Petawawa Research Forest. This is the main entrance road to the facility. Under normal circumstances, the creek is so minor that you wouldn't even notice it while driving along the road. We surmise from the debris that the creek used to flow under Clouthier Road in a small concrete culvert.

Beaver dam in the Petawawa Research Forest

(photo by Bob: 2007-04-29 - map - explore

In the middle distance is the large beaver dam as it appeared in the spring of 2007. This is the dam that burst and caused the flooding. As is evident from this photo and from the satellite image, the dam was holding back a lot of water. It is about one kilometer upstream from Clouthier Road.

broken beaver dam in the Petawawa Research Forest

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This photo is from 2008 July 20. Bob is working his way out along the top of the dam to inspect the breach. You can see that the water level in the pond (to the right) has dropped several feet.

broken beaver dam in the Petawawa Research Forest

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The break in dam. But even with the break, the dam is still holding back several feet of water.

broken beaver dam in the Petawawa Research Forest

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At the edges of the beaver pond above the dam after the break.

broken beaver dam in the Petawawa Research Forest

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Another view of the beaver pond above the dam after the break.

washout due to broken beaver dam in Petawawa Research Forest

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The washout on R8 -- a minor road, not much more than a trail -- in the Petawawa Research Forest.

washout due to broken beaver dam in Petawawa Research Forest

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Looking upstream from the washout on R8.

washout due to broken beaver dam in Petawawa Research Forest

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A somewhat similar view from 2002 April. (You can match up the rock on the left hand shore and the dead tree in the background.)

washout due to broken beaver dam in Petawawa Research Forest

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The creek bed between R8 and R9. (R9 is another minor road within the Research Forest.)

washout due to broken beaver dam in Petawawa Research Forest

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At the washout on R9 looking downstream. (R9 runs across the foreground of this photo.) Since it appears that this road is not being maintained and is being allowed to grow in, this washout is likely of little significance .

washout due to broken beaver dam in Petawawa Research Forest

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Looking upstream from the washout on R9.

washout due to broken beaver dam in Petawawa Research Forest

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From 2007 August. Note the beaver dam upstream. It, along with several others were washed away in the recent flood.

beaver dam on the Chalk River along the Water Trail in the Petawawa Research Forest

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The beaver dam on the Chalk River at the observation tower on the Water Trail. There is no obvious sign of a surge of water at this location, though the creek enters the Chalk River upstream from this location. We assume that the surge was dissipated by washing out Clouthier Road and in the marsh adjoining the Chalk River.

Satellite Image

The beaver dam (leftmost marker) holding back the pond at R1 and Meridian Road was breached and the ensuing surge of water removed all of the several smaller beaver dams downstream. R8, R9 and Clouthier Road were washed out. However, the surge of water was not sufficient to remove the beaver dam on the Chalk River at the observation tower along the Water Trail (rightmost marker).

We were very impressed by the destructive power of this torrent of water. If one little beaver dam can do this, just imagine the scene when the glaciers retreated, and ice dams failed, and Glacial Great Lakes dropped a hundred feet or more.

We don't know whether the failed dam was being maintained and if not, what had happened to the beavers. Beavers were certainly active and making a mess around that pond a year or so ago.

Photos of the Washout in Progress by Renata Boulanger

The following photos of the washout in progress were taken by Renata Boulanger and provided by Marvin Dupuis. Thank you Renata and Marvin. (These photos were taken on the morning of 2008 July 08 from the west side of the washout and in all cases the water is flowing from right to left.)

Clouthier Road in Petawawa Research Forest washout from burst beaver dam
Clouthier Road in Petawawa Research Forest washout from burst beaver dam
Clouthier Road in Petawawa Research Forest washout from burst beaver dam
Clouthier Road in Petawawa Research Forest washout from burst beaver dam
Clouthier Road in Petawawa Research Forest washout from burst beaver dam