Irrigation Channel Hike on 600-year-old Undra and Laldneri Suonen

Sunday September 28, 2025 -- Every year our friends Jeff and Carrie visit us for a couple of days, and we take them to different parts of Switzerland to experience customs, history or technology that other tourists may not be aware of.

On this beautiful day we headed to Canton Valais in the south/southwestern part of the country, to experience a hike along one of the dozens of historical irrigation channels which have been the life-blood of this very dry region for centuries. The "technology" of how these channels were built is incredible. Water had to be brought from rivers at the far back of steep valleys, and directed at exactly the right slope to allow the water to flow, but not too steeply so it would still reach the Rhône Valley high enough to distribute the water to the farms on the hillsides. This often meant starting construction at high elevations along vertical cliffs, hewing channels into the rock faces, attaching board-walks to access the channels for upkeep. Many lives were lost in the process. Every community had to provide workers, or pay large fees for the use of the water.

There are many vertiginous walkways higher up, but we walked on the "tamer" trails lower down in the Baltschieder Valley near Visp, starting in the typical Valais village of Ausserberg, following the Undra and then the Laldneri Suons (channels) to the train station in Eggerberg, before heading back northwards through the upper Lötschberg Tunnel with the BLS train to Thun on Lake Thun. 

After a 23-minute bus ride from Visp, we were in Ausserdorf village at 1:30 p.m. First thing obviously, was a look in and around the Catholic Parish Church (this one is fairly recent, built end of 19th, beginning of 20th Centuries).

The winged side altars are particularly pretty. The one on the right is a copy of the 1400's original which is currently in the Federal Museum in Zurich. The one on the left is from the Late Gothic Era. 

Walking through the cemetery. 

Instead of headstones, every grave here is fitted with a sculpted wooden cross. 

View from the south side of the church, down to the city of Visp and into the Visper Valley. (This valley later splits into the Saas Valley and the Matter Valley, at the end of which you can find the Matterhorn.) 

There are very many of these wooden storage barns called "Spycher". They are set on "mushroom" pedestals to prevent mice from accessing the inside. These are some of the oldest buildings in the village. (Age unsure, possibly 15th Century?)

Starting off on our walk up into the village of Ausserberg, along a lovely cobblestone road. 

This barn is atypical as far as these structures go, as it has additions on both sides, which you don't see a lot. 

A good look at the church now as we head up through the village. 

Far to the east are the snow-covered peaks of the Goms Valley. Many of the buildings had these pyramid-shaped stones on the slate roofs. (I was not able to find information on this).

Walking through the village of Ausserberg. 

A variety of the old buildings in this village. 

Taking advantage of a village fountain to stock up on water for the coming two-hour hike into the side valley. 

For the first 30 minutes, we follow the BLS High Trail no.61: "Walliser Sonnenweg" (Valais Sunshine Trail) until we reach the junction into the Baltschieder Valley. 

We chose this walk along the Undra and Laldneri Irrigation channels because we could start by bus right from the center of the village of Ausserberg, and didn't have a lot of uphill to walk to the train station in Eggerberg. We started in Ausserberg at about 1:30 p.m., and caught the 16:43 train in Eggerberg. 

Along the way, a little chapel on the hill. It is called the Theresien Chapel, built in 1934-1935. We had a quick look inside, a typical small Baroque altar (apparently from the early 20th Century). 

An easy 30-minute walk along the BLS High Trail from Ausserberg to the junction of the Baltschieder Valley. 

As we reach the Baltschieder Valley, we can see the mountain village of Eggen on the far side of the canyon. We will be walking on a trail somewhat below there, back into the Rhône Valley. We started into the valley here at 2:35 p.m. 

Now starts the interesting section along the Undra Irrigation channel, a channel built in about 1377, and the water still flows to this day, drawn from the back of the valley to water the farms on the Rhône Valley side. 

The Undra Suone from here to where the water is diverted to it is 3 kilometers long, runs water all year round, and is bordered by an easily walkable trail, although at some places with quite a steep drop (up to 200 meters) to the Baltschieder River below. We are only walking half of that, before returning on the other side of the valley. 

The water is drawn from the Baltschieder River at 1100 meters above sea level. It is the lower channel, and one of the oldest channels in this valley. (Documents from 1377 claim this is a "new" channel!). The water was also required for providing drinking water, and thus must flow all year long and be kept clean. 

Directly to the south now we can see into the Visper Valley to the Mischabel group of peaks, which contains most of the 4000+ peaks within the Swiss Alps. At the junction below this massif, the left valley leads to the Saas Region, and the right valley heads off to Zermatt / Matterhorn (which is not visible from here). 

A nice walk enjoyed by us all. 

A common sight in autumn: The poisonous Fly Amanita. 

It is hard to see how steep the drop into the canyon is.

This was probably the most "exciting" part of the trail. It wasn't scary or difficult, we just had to watch our step. 

Keeping the balance! (Here the water has been diverted through a tunnel blasted into the rock years later. Originally, the water would have been diverted via wooden troughs attached to the outside of the cliff, where the trail currently is. )

Carrie taking a photo of us as we round the corner. Here you get a better idea of the steep drop next to the trail. 

(Side note: This is the lower, less "dangerous" irrigation channel. About 200 meters above us is the Niwärch Suone, one which we walked in September 2019, and which is considered probably the most spectacular in the region.) 

Along the way are gates which are used to control the diversion of the water to the farms below. 

After 40 minutes walking along the Undra Suone, we headed back "out" of the valley on a lower trail, heading toward a bridge which crosses the Baltschieder River, and then continued along another irrigation trail on the east side of the valley. From here it's another hour or so to the train station in Eggerberg. (It is currently 3:15 p.m., and we are aiming for the 16:43 train). 

Far above us now, on the east side of the valley, we caught sight of one of the historical wooden troughs which were common along the outside of the cliffs. This is part of the Gorperi Suone, another 150 meters higher up, and one that we have walked twice now. At that point, the water has also been diverted via a tunnel, but it is still possible to walk along one such section, something I tried to do when we were there last in September 2023, but I did not have the courage to cross it. (Specifically, THIS PHOTO)

Here we now cross the river from the west side to the east. At the back of the Baltschieder Valley, the peak called Stockhorn dominates the view. 

This now is a different irrigation channel called Laldneri, also built in the 14th Century. It was very pleasant to walk here. 

VIDEO:

A sample of the walk along the Laldneri irrigation channel

Jeff noticed that a large section of this cliff is quartz rock. 

We are just above the tunnel of the BLS south ramp railway line. Later, once we get on the train at Eggerberg, the train will pass by here on the way up to the Lötschberg tunnel. 

Another, closer look at Mt. Stockhorn towering at the back of the Baltschieder Valley. 

This trail was less vertiginous, and there were all kinds of different features along the trail, i.e. wooden or metal troughs which the water flowed through. 

Here it's a metal trough 

Near the south end of the valley, we can now see the South Ramp of the BLS railway line which we will be riding later. The trail we had walked from Ausserberg runs about 150 meters above the railway line. 

Final stretch as the trail now heads back into the Rhône Valley 

Another look down on the city of Visp. 

We did see a few of the famous "Valais Black-Nosed Sheep", but they had all been recently shorn and not nearly as cute as the wooly ones. 

Below us is the parish church of Eggerberg. We didn't have enough time to do a detour to there. 

Main street in Eggerberg. We arrived here from the irrigation channel at 16:34, in plenty of time for the 16:43 train from the station, which isn't far from here!

A final look to the Mischabel Group. (The highest mountain fully on Swiss territory, Mt.Dom -- 4545 meters -- is in that massif). 

Satisfied with our accomplishment, we have a few minutes to rest before heading toward the next goal of the day: A stopover at the city of Thun in the Bernese Oberland, on the west end of Lake Thun. 

The BLS train arrives right on time at 16:43. 

Final look down into the Rhône Valley (the Rhône River heads from here into Lac Léman -- Lake Geneva -- to the west). From here we travel 1 hour and 15 minutes via the upper Lötschberg Tunnel and Kandersteg/Spiez to the city of Thun. 

What our hike looks like on Google Satellite Maps. 

These are all the hikes we have done in the region between Ausserberg and Eggerberg and in the Baltschieder Valley. (Including trails along four different irrigation channels).

These are more hikes we have done in the area around Visp, including the Eischoll-to-Unterbäch walk which we did before doing the irrigation trail walk. 

On the north side of the tunnel is a panoramic stretch along the Kander Valley. Here a spectacular view of the magnificent Blüemlisalp Massif. 

And now we have reached Lake Thun, with views of Mt. Schrekhorn, Eiger and Mönch (Mt. Jungfrau off photo on the right). 

PHOTOS from our subsequent visit of the quaint town of Thun can be viewed HERE. This blog also includes photos of the previous excursion we did this same day, crossing the Milibach suspension bridge between Eischoll and Unterbäch on the south side of the Rhône Valley before heading up here to Ausserberg for the two-hour hike along the irrigation channels. 

This map shows the location of the city of Thun as well as the area near Visp where we did the first two excursions of the day.