The work on the River Stour will benefit a variety of wildlife
A project to help threatened wildlife is currently taking place on the River Stour at Bures.
The Essex Wildlife Trust is looking at ways to allow fish, particularly eels, to migrate up the river.
Darren Tansley, Wildlife Officer said: "They [eels] are a biodiversity action plan species in Essex. They are a species which is diminishing.
"We are trying to get a real handle on why this is happening. A lot of this is because they can't get to the habitat."
Eels are an important food source for another threatened species, the otter.
"Otter absolutely loves eel, especially in East Anglia where it appears to be a fundamental part of their food resource," said Darren.
The Environment Agency is carrying out work to reconnect the old meander which runs alongside the River Stour.
The scheme is jointly funded by the Essex Wildlife Trust and the Environment Agency.
"Both Essex and Suffolk County Council put in matching funding money so we could get our Biffaward grant," said Darren.
The project means there is a continuous flow of water along an historic dried-up channel, which will allow eels to travel up stream.
The River Stour forms the county boundary of Essex and Suffolk
"Hopefully, we'll have more eels in the upper reaches, meaning more food for the otters," said Darren.
"A fantastic coincidence that we've got a little water vole population, which is also going to benefit from this new channel," he added.
It is hoped that the work will be completed by Christmas.