The River Wansbeck at Mitford is being returned to its original course following the construction of a flood storage dam.
For the past 12 months, it has flowed along a temporary 100-metre channel to allow the large structure to be built.
Now that the construction is nearly complete, works have started to divert the watercourse back to its original route, which will flow through a number of culverts beneath the dam.
When heavy rainfall increases the water level in the Wansbeck, the culverts restrict the amount of water that is able to flow downstream through to Morpeth.
Anthony Myatt, project manager at the Environment Agency, said: “The diversion of the Wansbeck was vital to allow the construction of the storage dam, and now we’re at the important stage of directing it back under the new dam.
“The culverts at the bottom of the dam will then control the rate of flow of the river in times of high rainfall, keeping the river at a safe level in Morpeth, and they will be complemented by the improved flood defences in the town itself.
“Once the river has been diverted to its original course, we will be able to start the earthworks to build the dam embankment.”
A white-clawed crayfish relocation took place last year, but it is possible that some of them may have moved into the temporary channel, so it will be checked before it is closed off and refilled.