Young Edgeley Road vole swims past, spots me...
It does happen. White Lion Meadow was stuffed with water voles in 2006, and yet now the numbers are much reduced. The voles who live under the railway bridge at Homebase disappeared over the summer a couple of years ago, but came back the following spring and we never knew why. And of course last July the Greenfields/ Whitchurch County Park site was cleared out by mink, only this year it's recovered well and there seem to be more voles down there than ever.
Water vole colonies are fragile and need monitoring and occasional intervention (eg reporting pollution to the Environment Agency). If the problem is resolved and there are water voles living nearby, vacated areas can fill up again fairly quickly.
We don't know what's caused the crash at the Prees Branch Canal - my guess is mink - but I do hope next year there's better news.