The Nantes–Brest Canal between the Guerlédan Dam and Saint-Aignan

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Between the Côtes-d'Armor and Morbihan. Following the Guerlédan trail, you climb up to overlook the dam built around 1930 to supply the region with electricity, then through heathland and woods, you descend to the Nantes–Brest Canal.
As you pass through the village of Saint-Aignan, you’ll come past an interesting little church and the electricity museum. Also worth seeing on the way out of the village is the small Saint-Aignan dam.

Details

n°4884764
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  • Walking
    Activity: Walking
  • ↔
    Distance: 7.37 km
  • ◔
    Average duration: 2h 25 
  • ▲
    Difficulty: Easy
  • ⚐
    Back to start: Yes
  • ↗
    Ascent: + 105 m
  • ↘
    Descent: - 105 m
  • ▲
    Highest point: 155 m
  • ▼
    Lowest point: 74 m
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Photos

St Aignan Church
Guerlédan Lock
Guerlédan Dam
View of the small dam at St Aignan

Description of the walk

Start from the car park at the top of the small beach or from the Rond-Point du Lac.

(S/E) Head down to the beach. Then follow the Guerlédan path to the left (green signs) and walk along the lake on your right. Flat at the start, the path quickly becomes more rugged. Follow it uphill to a junction which marks the highest point of the route (beautiful view of the dam and the surrounding forest).

(1) Take the path on the left towards an old quarry, leaving the marked trail. Cross a small mound of gravel, go round a gorse bush on the right and then follow a path straight ahead alongside a wire fence. Note the small lake on the left formed in the hollow of the quarry and follow the path to an electricity pylon.

(2) Then head down to the right, following the most clearly marked path (south-west then west). Reach the road along the banks of the Blavet.

(3) Follow the road to the left until you reach the footbridge at the Guerlédan lock.

(4) Cross the footbridge and turn immediately left onto a grassy path between the canal (on the left) and the Blavet (on the right). Continue straight on until you reach the next lock and a road.

(5) Turn right onto the road and cross the Blavet.

(6) Immediately turn right onto the D31 towards Saint-Aignan. Pass the cemetery, go through the village and pass a small chapel (with the Electricity Museum opposite). Continue straight on for another 200 m or so.

(7) Take thefirst right to see the small Saint-Aignan dam, then retrace your steps.

(7) On your return, continue right onto the main road and immediately turn right onto a path leading to the banks of the Blavet. Pass a group of buildings.

(8) At the next junction, turn right to reach the Guerlédan lock and cross the footbridge again.

(4) Then turn left.

(3) Continue straight on along the Blavet. When you reach a barrier, climb up to the right onto the path marked “Sentier de Guerlédan”, which is very steep.

(1) At the highest point reached on the way out, continue straight on to the beach. Then head up to the right to reach the car park (S/E).

Waypoints

  1. S/E : km 0 - alt. 139 m - Car park at the top of the small beach - Lac de Guerlédan
  2. 1 : km 0.79 - alt. 143 m - Viewpoint - Junction
  3. 2 : km 1.13 - alt. 152 m - Electricity pylon
  4. 3 : km 1.57 - alt. 83 m - Road along the - Blavet (fleuve)
  5. 4 : km 1.76 - alt. 85 m - Guerlédan Lock - Canal de Nantes à Brest
  6. 5 : km 3.57 - alt. 81 m - Quénécan Lock
  7. 6 : km 3.86 - alt. 78 m - Junction – D31 road
  8. 7 : km 4.9 - alt. 84 m - Access to the Saint-Aignan dam
  9. 8 : km 5.75 - alt. 85 m - Junction
  10. S/E : km 7.37 - alt. 139 m - Car park at the top of the small beach - Lac de Guerlédan

Notes

An easy route, although the climb along the dam is very steep; steps make it easy to navigate the steepest sections. Good walking shoes are essential for the section along the lake and the descent down the dam.

Worth a visit

Along the route:
The dam, a former quarry now filled with water, forming a lovely little lake.
The Nantes–Brest Canal

Things to see in Saint-Aignan:
A very interesting chapel with a beautiful Tree of Jesse.
The Electricity Museum.
On the outskirts of the village, a small experimental dam.
A small bird observatory.

Reviews and comments

4.1 / 5
Based on 6 reviews
Reliability of the description
4 / 5
Ease of following the route
4 / 5
Route interest
4.3 / 5
User 26625056

Overall rating : 4 / 5

Date of your route : Jul 29, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★☆☆ Average
Route interest : ★★★★★ Very good
Very busy route : No

from the outset, either I didn't understand the route or it was poorly signposted, because I took the wrong path. But with a map and a compass, I quickly found the trail again. I changed my route at the end to follow the EDF power station and reach a section of the forest with a view of the lake. The path was quite steep, winding between rocks, roots and wooden steps (for those with a Capricorn ascendant) lol. A lovely little hike.

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Schoulp
Schoulp

Overall rating : 4 / 5

Date of your route : Oct 09, 2023
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

A lovely walk. The start is a bit tricky.

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MARNOY
MARNOY

Overall rating : 5 / 5

Date of your route : May 23, 2022
Reliability of the description : Not used / Not applicable
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : Yes

An interesting route, though a short section of the road is less so, but that’s unavoidable.
Overall, a varied route that really showcases the different aspects of this dam region.
It was busy but not “very busy”; the weather was fine and it was a normal weekend.

Well done, Visorando!

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cesttropinjuste
cesttropinjuste

Overall rating : 3 / 5

Date of your route : Jul 19, 2021
Reliability of the description : ★★★☆☆ Average
Ease of following the route : ★★☆☆☆ Disappointing
Route interest : ★★★★☆ Good
Very busy route : No

At the start of the route, everything is spot on. There’s even a stunning view of the dam.

At stage 4, we’re told to take the green strip of land between the two bodies of water. However, this area is off-limits because it’s dangerous. There are signs put up by EDF, which are unfortunately hard to see at the entrance to the grassy strip, explaining that the area is dangerous and off-limits. It is a mound used to regulate the water in the event of a dam failure and which can become submerged. You can continue along the road instead of taking this grassy strip, and it leads to the same place.

On the way back, we do not take the same steep path as on the way there but make a circular route to the right. The problem is that this path, which is clearly rarely used, is overgrown with brambles, making it impassable and difficult to follow even with a GPS. Furthermore, the vegetation is so dense that it may lead into an industrial wasteland that appears dangerous, given the signs and barbed wire we encountered.

In short, be very careful on this route, which appears easy but leads into dangerous areas.

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mahornsolo
mahornsolo

Overall rating : 4.3 / 5

Date of your route : Jun 18, 2021
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : Yes

A lovely route, with a very steep section near the dam, starting from the beach at the roundabout by the lake and heading towards St Aignan.

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mariedaniel
mariedaniel

Overall rating : 4.7 / 5

Date of your route : Mar 06, 2021
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

-A pleasant route with no difficulties downstream of the dam (the Nantes–Brest Canal – Blavet Valley), unlike the section overlooking the dam, which is very steep and rugged but offers magnificent panoramic views. The route winds through a hilly, wooded landscape where water is ever-present.
-Naturally, due to Covid-19, the Electricity Museum in Saint Aignan in Morbihan (opposite the parish church) was closed.
-The walk took place in excellent conditions, with sunny and dry weather, on Saturday 6 March 2021.

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