On 5 August 2025, we made the following observations at the Witenwasseren Glacier (Uri Alps, Switzerland):
Witenwasseren Glacier and western glacier lake on 5 August 2025.
The Witenwassern Glacier was largely free of snow on 5 August 2025. Since our last visit on
13.7.2022, the glacier has continued to lose length and mass.
Witenwasseren Glacier and eastern glacier lake on 5 August 2025.
The eastern glacial lake has not changed since
13.7.2022. Only the delta has become slightly larger.
Delta of the eastern glacial lake on 5 August 2025.
Green part of the delta of the eastern glacial lake on 5 August 2025.
Part of the delta was covered in a delicate green: the pioneer vegetation was able to establish itself further.
Witenwasseren Glacier and middle glacier lake on 5 August 2025.
The middle glacier lake has continued to grow in size.
Middle glacial lake on 5 August 2025.
Legend:
1) A small amount of dead ice can be seen beneath the debris.
2) The western glacial lake will be drained via the middle lake. See also the following sections.
Overview of the western lake in front of the Witenwasserengletscher glacier on 5 August 2025.
The western glacial lake has continued to grow in size since
13.7.2022. An ice wall approximately 10 metres high has formed on the western side. A few ice floes floating on the lake indicate that small pieces of ice have broken off from this ice wall.
Legend:
1) The ridge that separated the middle and eastern lakes has largely melted. As a result, the western lake is now drained via the middle lake and the water level of the western lake has dropped by approximately 2 metres.
2) Presumably until early 2025, the area around number 2 was still covered by the western lake.
The remaining western lake with an ice wall in front of the Witenwasseren Glacier on 5 August 2025.
The western lake in front of the Witenwasseren Glacier on 5 August 2025 from a different perspective.
Sediment deposits became visible due to the western lake being approximately 2 metres lower.
These deposits are quickly eroded and thus flattened/rounded off.
Transition from the western (right) to the central glacier lake (left) on 5 August 2025.
In 1), the western lake was probably dammed up until early 2025 by a ridge of ice covered with boulders and debris. As the ice melts, the water no longer flows eastwards via a stream, but into the middle lake in a south-easterly direction.