Hiking

Ru de By from Plan du Débat

Details

Plan du Débat

Departure location

Doues

Municipality

suitable for all

Effort

Difficulty

4.0

Rating

105 m

Ascent vertical drop

4h 10m

Total time

Description

Services in the surroundings

Ollomont Town Hall

Ollomont 1.853 m

Cross-country ski run Ollomont

Ollomont 1.851 m

Nearby attractions

Parish Church of St. Augustine

Ollomont 1.888 m

Reviews

14/04/2026

biella10

Description

Siamo partiti dal divieto di transito posto a circa due chilometri dopo l’area picnic Belvedere. Da Plan Dètruit habbiamo trovato neve; all’andata siamo passati lungo il Ru per poi scendere alla strada che ci ha portati all’Alpe Cá Ansermin. Trovato ancora molta neve. Siamo scesi facendo la strada in modo da completare, nel finale, un piccolo anello. Abbiamo visto cadere una slavina, alla destra orografica della Tsa. Visto marmotte. Francesca ed Alessandro (CAI/ANA Biella)

Comment

Oramai la neve non è più portante.

More info

Road access: Alcuni cantieri sulla strada della Valpelline.

Details

Plan du Débat

Departure location

Doues

Municipality

suitable for all

Effort

Difficulty

2h 10m

Ascent time

2h 0m

Descent time

4h 10m

Total time

2.076 m

Starting elevation

2.179 m

Arrival elevation

105 m

Ascent vertical drop

16.000 m

Total length

TDC

Signposts

Jun - Jul - Aug - Sep

Best period

medium

Crowding

4.0

Rating

Overview

The "Ru" are man-made canals built between the 13th and 15th centuries to bring water from territories that are rich in it due to their high mountains with glaciers or snowfields until late in the season,to drier territories, either for the purpose of irrigation to make the fields cultivable or for the water supply of the population.
One of these is the Ru de By (also known as Ru de Champillon), a long canal that served to channel the waters from the streams of the high peaks above the Conca de By, carrying them to the territories of Doues and Allein.
This is a fairly long route for its development, but not very strenuous and almost flat. The variety of landscapes and the continuous succession of different scenarios that the Ru crosses will make the hike a joy for the eyes, suitable for everyone with the only attention to two slightly exposed passages where there are fixed ropes.

Reaching the start

From the Aosta East tollbooth take the tunnel along the E27 road leading into the Great St. Bernard Valley, at the end of which you meet the SS27 coming from the center of Aosta. Just before Gignod, immediately after the last tunnel, proceed to the right following the Valpelline SR38, which should be followed for 3 km until meeting on the left the junction for Allein/Doues.
The road now begins to climb with hairpin bends reaching the center of Doues. Just before the square turn left following the signs for Champillon, which will be reached in 12 km on a well-paved mountain road touching the many hamlets of Doues. Large dirt parking area at Plan du Débat.

The route

From the unpaved parking area at Plan du Débat, you immediately skirt the Ru that flows on the Champillon Refuge side, taking the Tour du Grand Combin (TDC) trail, which crosses open pastures with the first panoramic views of Grand Combin and Mont Gelé. Flanking the watercourse, you enter a cool, wooded area, passing alongside the little church Our Lady of the Snow just above the Champillon Alp.
You cross the dirt track that goes up to the Champillon Refuge and continue on the Ru trail, always flat, momentarily leaving the Néan 2085 m forest. From here on, the Ru will no longer be visible, because it flows intubated below the track, which becomes very wide.
The track continues in an inlet of the valley ploughed by a few streams, until it passes the alpine pastures Plan Cortou 2091 m and Ansermin 2216 m. Just below is always visible the dirt track that leads to the Conca di By.
We finally leave the wooded areas, which give way to vast pastures that in early summer offer a multitude of flowers and colors; after skirting the flanks of Mont Rond, we reach a characteristic terrazzo passage equipped with ropes that provides for a narrow gorge carved between the rocks, at the end of which are the remains of the Econdù 2140 m pasture, which means hidden.
We cross the vast Comba de Berrouard, furrowed by several streams, rushing in late spring, below the southern slope of Mont Velan with the Praz du Champ and Pleytau alpine pastures below. After crossing more streams, you reach the second passage equipped with ropes, a bit more exposed than the previous one because you have to lean out slightly to get around an overhanging rock.
Having overcome the obstacle, the route becomes easy and scenic again, at an altitude of 2173 m you meet the junction for the Rosazza Refuge at Savoie, and below the small road to the Porchère pasture. You go around the grassy ridge above, and shortly afterwards the view widens to the lush Conca di By with its characteristic turquoise-colored artificial lake. A few dozen meters later you reach the junction with the TDC trail that descends to reach By. Here you can consider the hike finished, and you can relax while enjoying the views offered by this trail.
The Ru de By continues for about 1 km further upstream from the junction, reaching the de By stream where some hydraulic works channel it.
The return is along the same route as the outward journey, this time you will be able to admire the views of the southern side of the Aosta Valley, with Mount Emilius dominating the scene.