The Environment Agency said the low oxygen level in Pittville Lake could be algal bloom or sediment stirred up by rain, or both.
The Environment Agency has reported a significant number of fish have died in Pittville Lake in Cheltenham.
They said it is due low oxygen and are trying to save as many as possible.
Tests to show how clean bathing waters are in the South West start today.
The Environment Agency will be taking samples and telling people where is safe to swim. Last year 98 per cent of beaches in our region reached current standards.
The Agency will be taking samples from today until the end of September.
There are three flood warnings in place in the region tonight. The first is for Salt Moor and North Moor, including East Lyng, Burrowbridge, West Yeo, Moorland and Fordgate.
There is also one for the A361 East Lyng to Burrowbridge and Curry Moor and Hay Moor. More rain is expected overnight and people living in areas at risk are advised to take action.
The Environment Agency has issued five flood warnings affecting our region. If you are at risk of flooding you are advised to take the usual steps to protect yourself and your property.
- Somerset coast at Portishead and Portbury Dock, seafront properties
- Somerset coast at Clevedon, seafront properties
- Somerset coast at Blue Anchor, seafront properties
- Tidal River Avon at Pill and Shirehampton, Watch House Road and Station Road areas
- Somerset coast at Porlock Weir
You can keep up with developments on the Environment Agency website.
The Environment Agency has issued a flood warning for the River Chew from Chew Stoke to Keynsham near Bristol.
20 to 30mm of rain was forecast to fall between 6 pm tonight and 6 am tomorrow (Saturday), with up to 40mm possible in isolated areas.
Levels on the River Chew at Compton Dando are stable but are expected to rise reaching flood warning status at about 3am on Saturday morning.
People whose homes are at risk should take appropriate action.
The VW Show due to take place on Sunday at Berkeley Castle in Gloucestershire has been cancelled due to the bad weather. Organisers say the field is waterlogged.
They say a new date will be set for next year in due course. All exhibits and stalls will be valid for the new date.
The main road between Milverton and Wellington in Somerset is flooded.
These pictures were taken by our Somerset correspondent David Woodland, and show floodwater coming off the fields at Chipley.