Come off at junction 24 and take A57 towards Denton. Get in the far left lane otherwise you'll end up on the M67. Go left at the lights onto Corporation Road. Follow this all the way over the speed bumps until the mini roundabout and then go left onto Stamford Road. Follow this to the roundabout and then left onto Audenshaw Road. After about 100 yards you'll see the Blue Pig pub on your right (you've gone too far if you cross the motorway). Park on the road by the pub, cross the road to the big emabankment, go through the gate and this is Audenshaw reservoirs. Keeping one eye to the ground at all times so as to avoid dog crap disaster, go up the bank and follow the causeway between the two reservoirs (res 1 on your left and res 3 on your right) to reservoir 2 at the far south end. You could also come off at junction 23 but I don't know that way as I'm coming from south Manchester.