More than 100 Gosport residents spent Saturday rescuing fish and marine life in Alver Creek, a tidal lake of Portsmouth Harbour, which had been left stricken by the recent hot weather.
Southern Water was called to the scene over concerns the water had become contaminated.
After finding the mass die-off was caused by a lack of oxygen in the water, technicians from the company, which is not responsible for the waterway, used specialist equipment to increase the oxygen levels.
Technicians on the scene had sought guidance from the the Environment Agency before using the equipment, according to a spokeswoman from the agency.
She said: ‘Once contacted the Environment Agency agreed that using aeration equipment could be carried out and would be a sensible approach.
‘We also confirmed our permission wasn’t needed, as we are not the landowners of this location.
‘Using pumps to aerate waters with low oxygen levels is used often. This is not a polluting procedure and the Environment Agency would not need to be consulted as to whether it can be used.’
‘There is a caveat, we generally wouldn’t advise deploying pumps in shallow water as this would kick up sediment which could also harm fish.’
The Environment Agency has asked residents not to move fish to different waterways in order to save them, as this can cause long term damage to fish stocks and spread harmful parasites and diseases.
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