Sheeba and Bryn on the dam at Lynne Brianne Reservoir. You can walk over the dam heading to the left, and having crossed over the dam you head around the dam on rough tracks curving around to the right.
We have never gone all the way around as the tracks goes on for miles. You cannot do a circular dog walk around this reservoir as it is too large. However one may be fooled on this walk into thinking one is coming back on a circle as you go around a long curve that heads back towards the dam for a while - however it doesn't!
You might be able to cycle around more of it though. If walking the dogs, take a picnic and walk in one direction for an hour or two and then walk back again.