Recently a brown/green algae has appeared in our club's reservoir, normally the water is gin clear, what could be the cause of this?, our members are looking for possible solutions, we would be most grateful for any advice.
the area of water is 33 acres, it has no natural inlets and is surrounded by farmland.

Phosphate run-off from the above. Barley straw floated in net tubing has been shown to help.

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Don't worry, be happy.
Sandy
Carried it in full, then carry it out empty.

It's known as Eutrophication and is normally a slow-ageing process for most, if not all closed waters.
The process can be greatly exaggerated, and sped-up, by the introduction of phosphates and nitrates run off from farm land, just as Fishtales says.
This causes extreme algal blooms, and gets worse later in the season as water temperatures rise, oxygen levels become lower, and the decomposing algae further extracts even more oxygen from the water and can be responsible for sudden fish kills, as well as the death of most other creatures in the vicinity.

hello could be like sandy said or this hot weather, many lakes in the south same, have heard there is a drought warning soon, maybe hose pipe ban. where did all that rain and snow melt go? out those leaky london pipes??

We are writing to Scottish water, asking permission to put straw bales in the water, but, I have seen the attempts made by the water board at Ravensthorpe, where they have had a large area of straw bales laid down and it has had very little effect on the algae.

Some of our long term members say that we had this problem about 15 years ago and it died off, is there any danger in a wait and see policy?

Run off from the farmland around the reservoir is captured in a drain that goes around most of reservoir, but, one field drain was led into the water about 5 years ago, with the water boards permission, we have only seen natural manure spread, could this be a possible source?.

Was it Barley straw? If it was just ordinary straw it doesn't work.

Manure is full of phosphates and nitrogen so it will affect the water as it leaches into it from the ground in wet weather.

http://www.soilcc.ca/ggmp_fact_sheet...e%20manure.pdf

The field drain will allow direct access of the nutrients which means they will be more concentrated. Planting reeds and marginal plants around the outlet may help.

__________________
Don't worry, be happy.
Sandy
Carried it in full, then carry it out empty.

Just plonking bales of straw into a water is a waste of time and effort.It does work to a certain extent,if done properly.

The brown algae has effected quite a few waters this year as a result of the harsh winters of last year.Available oxygen has been eaten up due to ice covering the water for so long causing a vacume and then it will gorge when clear again and then die off.

There is also no doubt that run off from fields which have had nitrates on it will encourage growth of algae.If you think about it ,nitrates are for encouraging growth of plants.
There is many types of algae,some are rare but are about and some more devasting than others.

Just read Sandys post and he is quite right.Reeds are a good way of helping protect your water as they suck out these nitrates and help keep it down.If you notice on a water where they are planted,there is always a heavier concentration of alge there and they act as a draw to that area.

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Kevin

Thanks for the posts so far, anyone else with information on this subject please post.
We may be a bit lucky with the field drain, it runs in to our water right in the middle of a sustancial reed bed.