It is believed there is blue-green algae present at both Lower and Upper Lymm Dam. This is according to Lymm Parish Council. The suspicions have been reported to Warrington Borough Council and the Environment Agency. However, the parish council said it would be a good idea to avoid letting dogs near the water as blue-green algae can be toxic. The algae causes risk to animals who often drink the water or lick algae off their fur.