Summer must be here

Summer must be here as the environment team are getting reports of blue green algae blooms, in our reservoirs and waterways all around the country. Blue green algae (BGA) are naturally occurring organisms but in nutrient rich waters and encouraged by warm weather, BGA can grow excessively and cause water quality problems and potentially health problems in the summer months.

BGA Olton Reservoir BGA Olton Reservoir

BGA can take many forms, one of it’s most recognisable is as a shimmering blue, green layer on the water surface, it can also appear as green streaks on the surface, as tiny green specks within the water or seem to change the water colour. At its peak, it can form scums on the water surface.  It is sometimes difficult to visually distinguish between blue green algae and other algae and the only way to get a definitive identification is by using a microscope. I would get an approved lab to undertake this work for me. 

I take any sightings of blue green algae seriously, as when it reaches the scumming stage, the algae can sometimes produce toxins. There are cases of dogs and cattle dying after they have drunk water containing BGA. The trouble is that there is no way of knowing which blue green algae is going to produce toxins. Large amounts of algae in a water system, can also cause dissolved oxygen problems – the algae will use up a lot of the oxygen in the water over night, so much that it can drastically reduce the amount of oxygen in the water which will can impact on fish and other aquatic creatures. 

Next steps

Once I receive a report that one of our reservoirs has BGA, I follow an internal process which involves  putting up warning signs around the reservoir, informing our external customers and internal colleagues and the Environment Agency. I also undertake a risk assessment – to see where the water body discharges to, if we have had any fish kills in the past and if any water activities take place on the water. The outcome of the assessment, is to decide on a monitoring regime, which can vary from weekly visual inspections to taking daily dissolved oxygen readings every day (for a site we are worried about).

The Environment team is also looking at ways of trying to reduce the algal growth, one big way is by reducing the amount of nutrient inputs into our reservoirs, we can only do this by teaming up with local landowners and environment bodies. I am also hoping to get involved in a University of Leeds research project, looking at blue green algae distribution throughout the canal network, it should prove really interesting.

Last date edited: 1 October 2015

About this blog

Sara has been with the Trust for 17 years, working in the environment team. She is a senior environmental scientist and will cover waste and water quality issues. She works closely with the South Wales and Severn Waterway team but her work will also pick up national issues, such as the Water Framework Directive.


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