Bala Lake - Biology

Biology

Bala Lake has abundant pike, perch, brown trout, roach, eel. It also contains the endemic gwyniad, now listed as critically endagered by the IUCN due to the introduction of the invasive and non native ruffe. It also contains the very rare mollusc Myxas glutinosa - the glutinous snail. According to legend, whilst the Dee itself flows through the lake, the waters never mix. However this was not confirmed by the detailed limnological work undertaken from the 1990s, as part of the work to understand and manage the occurrence of algal blooms on the lake. The lake now forms part of the River Dee regulation system and the level at its outflow is automatically controlled. Depending on flow conditions and the level of water in Llyn Celyn, water can flow either into the lake or out from the lake at the normal outflow point.

In the 1990s the lake suffered from blooms of blue-green algae which indicated a significant and worrying eutrophication of the lake. Investigation by the Environment Agency in partnership with the water industry, the farming community and others has put in place a plan for reducing pollution inputs to the lake.