The NWBC Pollution Control Officer has included an update on the incident from the Canal and River Trust. They have stated:

The Environment Agency’s officer is confident what we are dealing with is blue-green algae which has bloomed in the milder weather and frozen during this current cold snap. Apparently, this results in this stark visual phenomenon and can cause fish kills because of an associated crash in dissolved oxygen.

Blue-green algae is naturally occurring and therefore the Environment Agency will not be investigating this further. The Agency did conduct water quality monitoring over the weekend and found pH, dissolved oxygen, and ammonia levels were at suitable levels and therefore do not believe there is an ongoing water quality or pollution issue.

Canal and River Trust does not consider that blanket closures of reservoirs or canals are necessary. The central Health and Safety Team have advised that the Trusts duty is to warn water users of the health risks from their recreational activity in waters with BGA blooms. It is then the water users’ decision whether or not to continue with their activity at a particular site.

For most users who experience incidental water contact the advice is to avoid exposure to accumulation of scum (looking like blue green paint, grass clippings or floating mats), where the greatest concentrations of toxin may occur. In general scums tend to accumulate along the downwind shore-line. Users should also be advised to avoid water discoloured bright green or blue green (indicative of an algal bloom prior to scum formation),even though scum may be absent.