A water vole release pen on the river bank during the reintroduction project in 2010

The River Colne was the first major watercourse in Essex to have a fully-funded, catchment-wide mink control scheme. In 2009 ahead of water vole re-introductions, 16 mink rafts were installed and a total of nearly 100 mink removed in the first two years after which mink became a rarity. Water voles spread throughout the catchment but then the Covid lock-downs came into operation and in 2020-21 the rafts could no longer be checked. Mink had two seasons of relative safety to return to the river and water voles disappeared from their previous strongholds on the main channel. Those that remained were forced to move off river into ponds, side streams and tributaries.

Thankfully £0.52m funding for the Essex mink eradication effort was secured by Essex Wildlife Trust and the Waterlife Recovery Trust quickly installed smart rafts along the river and started trapping. In 2024 a total of 6 mink were caught and removed and although this was a very small number compared to the original trapping effort, these animals had obviously had a very significant impact on water vole. In the first half of 2025 no more mink were caught and the third year of water voles surveys at Fordham Hall Nature Reserve was underway. Although no water vole signs were found in March, by June a series of water vole feeding stations had appeared and a water vole latrine was also discovered a few km upstream close to a smart raft in Wakes Colne.

These early signs of water vole returning to the main river after an absence of 4 years show the effectiveness of mink eradication on making a river safe again. In addition the fact that only 6 mink could have had such a devastating impact on water voles illustrates how mink eradication is the only way to deliver a truly sustainable water vole recovery. We look forward to more good news as Essex and the Eastern Region moves towards mink free status.