Lac de Migouélou circular via Lac des Touest

Pass Arrens-Marsous and continue on the Route d'Aste (D105) towards the Tech Dam (pronounced "tèche"), along the Gave d'Arrens.
Pass the dam, continue for a few hundred metres and park at Plaa d'Aste (altitude 1400) in the car park on the right before the Migouélou hydroelectric power station.

(S/E) The trail starts from the car park next to the Pyrenees National Park signs.
The ascent begins immediately with numerous short hairpin bends!
After about forty hairpin bends, the trail enters the park. On the rocks on the right, you will see the characteristic red markings on a white background with a chamois head and the letters PN (Parc National).

(1) At around 1600 m, continue on the most obvious and clearly marked trail, without taking the purple trail on the IGN map to the left, which leaves the National Park and makes a detour.
At an altitude of 1773 metres, you enter the mineral landscape of La Mouic, bordered to the north and north-west by a ridge and its scree and breaches (including the Brèche de Peyralagor).
The trail continues to climb in switchbacks, overlooking the deep Arriougrand ravine on the left, the spillway of the Migouélou Dam, cluttered with granite boulders. In summer, the ravine is completely dry.
On the left in the background, the peak proudly rising up is Pic Cadier (2,676 m). It is not the highest in the area. Le Courquaou rises to 2,691 m, but is hidden behind it and cannot be seen.
At around 2,100 m, the trail gradually slopes westwards, without any switchbacks, overlooking a pretty gorge of a tributary of the Arriougrand and crossing a huge scree slope where the trail is well stabilised.
At around 2,200 m, above the end of the gorge, you can clearly see the Migouélou power station in the valley.
From there, you begin to see the first buttress of the dam. Continue west-southwest to the dam.

(2) (''To the right, the trail continues towards the Col de l'Hospitalet, before descending towards the Tech Dam'').
Once you reach the dam arches at around 2,250 m, the path slopes southwards, running along the foot of the arches.

(3) Leave the return path on your left. Continue straight ahead to the Migouélou Refuge. Several marmots have been spotted here.
(4) At the refuge (2,278 m), there is a beautiful view from the terrace over Lake Migouélou and the surrounding peaks.
This is a good place to take a well-deserved break, especially if the refuge is open and staffed (from 15 June to 15 September approximately).
Retrace your steps to elevation 2271.

(3) Two options:
- The return journey can usually be made by retracing your steps.
- Alternatively, for a more enjoyable but unmarked route, follow the Vallon de Masseys penstock, following the description below.

Off the marked trail: GPX track or IGN map at 1:25,000 scale essential.

Descend to the right, onto the platform along the large building. Pass between this building and the small square refuge and descend into the bed of the Ruisseau de l'Arriougrand stream.
Pass by the round stone tower (access to the gallery marked "Anc. mine", probably a chimney for visiting the hydroelectric facilities).
Continue eastwards along the small, barely marked path, indicated by a few cairns. The area is desert-like, almost lunar, with its granite rock formations eroded by water and ice and the marshy stream.
After about ten minutes, the path slopes southwards and becomes wider. The path surface is made of stone blocks covering orange electrical cables. From here, it follows the old EDF railway line.

(5) You will arrive at the foot of a metal footbridge on the old railway line, which is very well preserved.
On the right, you can access Lake Lassiédouat, its small dam and its control valve.
It is the perfect place for a secluded swim.
Cross the footbridge and continue along the old railway line, where the wooden sleepers are still almost all visible.

(6) You will reach a terrace at the start of the overhead section of the penstock. A small building visible from afar, housing the balancing chimney, overlooks the site.
Continue along the path, which begins to descend, first towards the foundations of an old stone service building. This must have been one of the living quarters for the workers who built the facilities in the 1950s.
On 14/09/2020, we unintentionally disturbed two ptarmigans ("partridges") resting in a copse.

(7) About a hundred metres from the old building, a flat area at the edge of a precipice allows you to admire (safely) Lac des Touest and its small lake below. The view is remarkable.
The path, marked by numerous cairns, then descends to the south-east, then to the east, then to the north-east, following the natural slope along which the penstock spreads its small piles.
NB: Given the good visibility of the trail, it is not necessary to follow all the bends shown on the IGN map; in fact, the OpenStreet World map does not show the same route.
Several viewpoints allow you to admire the lake up to an altitude of 1936 metres. A little lower down, at 1940 metres, a path even branches off to the right to reach the shores of the lake (see: During the hike or nearby, below).

(8) At around 1750 metres, the path crosses to the other side of the penstock and enters the Bois des Masseys.
The descent continues steadily through wooded terrain and then temporarily leaves the woods.
It is here, on 14/09/2020, on the left side of the path, at the edge of the rocky ridge that plunges into the Ravin de Lassiédouat, that we encounter a female izard and her kid, who are not disturbed by our close presence (100 m) and watch us continue our descent.

(9) At the edge of the forest, we leave the National Park and find a more marked trail leading off to the left and right.
Turn right and walk horizontally through a fairly damp area. Pass close to a drain. You can see the power station clearly below through the trees.

(10) Less than fifty metres further on, leave the horizontal path and take a path that descends rapidly into the heart of the coniferous forest. There is no path marked on the map, but it does exist on the ground!
Pass behind and to the west of the power station, near the spillway canal.
Exit the woods and continue towards the car park until you reach the road, then the car park (S/E).

Time required
For a total of 7 hours and 10 minutes, we really took our time!
The ascent to the refuge took us 3 hours and 10 minutes. This is a very relaxed pace.
We spent an hour and a quarter at the refuge, taking a long break and basking in the September sunshine.
The descent took us 2 hours and 45 minutes, with a 20-minute break at Lac de Lassiédouat and numerous breaks at the Lacs des Touest.

Equipment required
Bring the usual equipment for hiking in the mountains (hiking boots, suitable clothing, rain gear, water, food, survival blanket, knife, compass, map, whistle, GPS, etc.).

Water sources
No springs or streams (in summer) from (S/E) to (4). Bring 1.5 to 2 litres per person for the climb.
Free drinking water (except in winter) behind the refuge.
Then, from the refuge to the return car park, there are several streams, but the water is not guaranteed to be drinkable. Allow 1 litre per person.

Shelter in case of rain
No shelter during the ascent.
In , there is an unguarded shelter for 10 people (sleeps 3 to 4).
At the refuge, 34 beds (in season, from June to September), but only 8 places out of season.
In (5) or (6), the walls of the buildings can be used as shelter.

Safety
This hike is not recommended in winter when there is snow, as there are several couloirs, the last of which is very avalanche-prone (information from the refuge warden).
In case of low cloud cover, fog or wet ground, it is preferable to descend via the ascent route (more frequented and less steep).
(7) Do not approach the precipice with young children without taking precautions.
Otherwise, there is no particular danger.

Alternative ascent
You can ascend via Lac de Pouey-Laun from the Tech Dam.

Migouélou Dam
Built between 1956 and 1958 and commissioned in 1959, it has nine arches 31 metres high and 274 metres long, retaining a 48-hectare lake 96 metres deep. It supplies seven power stations, the first of which is Migouélou in the Plaa d'Aste valley.
From the Migouélou Dam, the water is turbined seven times by a chain comprising the Migouélou, Tucoy, Plan du Tech, Arrens, Aucun, Nouaux and Lau-Balagnas power stations before joining the Gave de Pau river. The water turbined by the Val d'Azun hydroelectric chain produces the equivalent of the annual domestic consumption of a town of 160,000 inhabitants, without pollution, waste or greenhouse gas emissions.
Source: Heritage of the Pays des Vallées des Gaves, from Lourdes to Gavarnie

Lake Migouélou is connected to Lake Pouey-Laun by an underground tunnel beneath the Col de l'Hospitalet and also to Lake Artouste by an 800-metre tunnel, currently disused, which passes under the Col d'Artouste and then via the Carnau lakes. Partially: Source Wikipedia

This is one of the most beautiful lakes in Azun. Despite being subject to heavy fishing pressure and harsh winters, this lake has a very interesting fish population (density, species). You can find large cristivomers, superb brook trout, Arctic char and lake brown trout. The fish can be very large... be prepared for surprises. It is necessary to use lures, live bait or dead fish of a respectable size if you want to tackle cristivomers and large brown trout.
This lake is stocked every two years with brown trout, Arctic char and cristivomers. Lascarats are stocked with the same frequency.
Sourcehttp://www.atout-pecheur.fr/

The Migouélou Refuge, managed by the Pyrenees National Park, was built in 1971 on its shores and now has a capacity of 34 beds. Source http://www.refuge-migouelou.com/

Lake Lassiédouat
In this small, unassuming lake, EDF agents catch fish over 40 cm long with a fish finder! Trolling and whip fishing are the two main techniques used in this biotope. Fly fishing can be used to explore the beaches and shallows, while English and bombette fishing allow you to find fish where they are active. On the slopes exposed to the sun in the morning, you can see ptarmigan, which alone makes it worth the detour.
The lake is stocked with brown trout and the small lakes with brown trout every two years.
Sourcehttp://www.atout-pecheur.fr/

Lacs des Touest
The large lake is a little paradise. Here you will find the flora and fauna of Azun, but due to its accessibility, the lake is subject to heavy fishing pressure. The only species present is brown trout, the queen of these waters. The lake is quite deep and the fish are active all day long, so spinning allows you to explore all layers of the water and find the fish. The upper pool remains a "puddle" where trout thrive. The Grand Lac is stocked with brown trout every two years.
Sourcehttp://www.atout-pecheur.fr/

Noteworthy points
You can spot all the surrounding peaks and passes with a good map and a sense of direction and/or a mobile app.
For example: La Pourgadou (2,344 m), Les Piques de l'Arriougrand (2,586 m), Pic Cadier (2,676 m), Pic de Batboucou (at the dam only; 2,586 m), Col d'Artouste (2,521 m), Col des Alianes (2,491 m), Pic des Tourettes (2,771 m), Pic Arrouy (2,708 m), Lurien (2,826 m), Grand Gabizos (2,692 m), etc.