Algal bloom turns Thatcham Lake green, but not toxic, expert says

Visitors to Thatcham’s Nature Discovery Centre have noticed the lake is looking quite green this week.

So, what’s behind it? A belated St Patrick’s Day stunt? The work of climate activists? No: A type of green filamentous algal bloom.

And while it smells horrid, it is in “no way toxic to people or wildlife”, says Andy Coulson-Phillips, principal ecologist at The Berkshire, Buckinghamshire & Oxfordshire Wildlife Trust (BBOWT), which manages the site.

But Mr Coulson-Phillips explained a potential problem could occur if the blooms die off and rot, which could lead to a drop in oxygen levels and possibly cause problems for fish later down the line.

He added that outcome is “far from definite”.

Newburytoday has reported in the past when other varieties, such as the dreaded blue green algae, left fish floating dead in the lake.

READ MORE: Fish die after algae bloom at Thatcham Nature Discovery Centre lakes

Mr Coulson-Phillips told Newburytoday: “It looks like green blanket weed, not the toxic blue green algae, which is in fact bacteria blooms.

“As far as I know, this kind of green filamentous algae is in no way toxic to people or wildlife.

“The algae is blooming because of high spring temperatures and falling/low water levels, which is causing a concentration of nutrients in warm water.”

Algal blooms occur naturally and are not uncommon during the summer months.

They have been a regular occurrence at this particular lake for several years, which staff at the visitor centre are aware of.

A spokesperson for the Environment Agency said: “We have checked our incident reports, and we had not been previously made aware of this algal bloom.

“We cannot tell from the photographs if this a blue-green algal bloom that could be toxic, or a green algae bloom that is not toxic.

“We will review this further with our ecological monitoring team to determine if a sample is required to be analysed.”

It urged people to report incidents such as this to its free 24-hour incident hotline on 0800 80 70 60.