Sedge (Carex nigra Group)

Sedge (Carex nigra Group)

Observation - Sedge (Carex nigra Group). Description: Found at the edge of a loch in the Scottish Borders. The stalks are triangular so I'm confident it is a sedge. Beyond that it's a bit of a guess and I'd appreciate guidance. Edit: Changed to match cicuta's ID. Many thanks.

Found at the edge of a loch in the Scottish Borders. The stalks are triangular so I'm confident it is a sedge. Beyond that it's a bit of a guess and I'd appreciate guidance.
Edit: Changed to match cicuta's ID. Many thanks.