As a guide to fishing a completely new water, I would always consult the wardens or bailiffs as to what the fish have been feeding on recently and productive areas. Hiring a boat is probably a good idea to start to learn a new water, all fishable areas are easily accessible, allowing mental notes of features, points, bays etc. Various depths, areas popular with bank anglers.
An absolute essential piece of kit if available, is a small map of the reservoir, which will usually include the compass points . I have a small wallet in my fishing waistcoat, in which I keep my maps showing named banks, woods, bays and features , allowing me to either choose a specific reservoir or bank area, allowing for the consideration of wind direction on the fishing day itself and that of the last few days. That is very important especially when deciding on upland waters, more so for selecting possible bank fishing opportunities.
When afloat I observe and make mental notes of features , areas of bank, bays and points, areas with deeper water close to the bank, useful weedbeeds that will hold fry and fry feeders from late August onwards, all knowledge that helps to predetermine possible good bank areas on which to fish. Areas of bank that consist of hard mud, soft sedimentation or shingle. This sort of information is most important, especially to the bank angler. On a stiff breeze, mud slicks can develop off points and soft mud banks, trout will not tolerate much mud passing through their gills, so to fish the edge of a slick can make for lots of fish running just outside the mud in the area of clearer water, if your bank position allows you to cast into the cleaner water, fine . On the other hand, if the wind turns and creates you fishing in an area of mud suspension, move your position for the fish will almost certainly have left that water.
Areas of interest to bank fish are where the topography or trees or bushes are affecting the surface water causing slightly more turbulence against a calmer edge as food will be channelled down the confluence and trout will quickly pick up on anything that offers them easy pickings. On any bank some areas of water may lay calmly against an area of rippled surface perhaps just catching a breeze, that ripple will disguise leader material, giving a favourable advantage.
Whilst your leader and fly are in diffused water it helps to disguise the leader material and definitely increases our chances of positive takes. I keep an eye out for any distinguishing features or marks on the water, foam lines, edges of calm lanes, all features that will channel feeding trout.
The same applies to thick green algae, trout will avoid such suspension, seeking clearer water.
Some general rules of thumb will apply, on bright days trout will prefer to feed in deeper water but may only drop to 3 - 4 feet if there is food available at that depth, buzzer or emerging sedge pupae .They can and do quickly respond to cloud cover, a decent cloud softens the glare of bright sun, so on bright days I make the most of every cloud opportunity. I usually have two rods made up, one with a team of nymphs and the second with dry fly rod ready to respond quickly to any surface activity. On the other hand, very, bright conditions can see our quarry at real depth on snail or bloodworm.
Midsummer will provide some magical opportunities to drift the edges of wind lanes, picking off the trout as they work their way up the lanes feeding on any opportune food as it lays trapped in the thicker surface meniscus film. Always worth a careful motor slowly parallel to wind lanes looking for surface activity of feeding fish, these lanes act like magnets in attracting the fish towards the food trapped in the increased surface tension.
Take advantage of any white-water slicks on a stiffening breeze, as again they will trap insect life and the trout will swim upwind taking advantage of the concentrated stream of insects. This applies to fishing dries or a team of wet flies. Fish are not necessarily always visible but are usually swimming upwind along the line of the foam slicks.
Each season has its sequence of likely food sources which will determine where we can expect to find and on what our trout are likely to be feeding on. Hence the value of keeping a record of our fantastic Reservoir journey each year to remind ourselves of the sequence of successes or more difficult periods.
I have always kept my Season Returns Books as well as fishing notebooks so I can recall various anecdotes and factual records from each season spent on each of the reservoirs I have enjoyed in both England and Wales. I have included in my retained notes both my own successes as well as those of others I have met throughout the seasons, if I felt that information could help me in future similar circumstances, I make a note.
Many of the anglers I have enjoyed either sharing a boat with or bank space, have taught me a lot from their own experiences.
Early season can see many fish in slightly warmer water feeding on vast hatches of buzzer, blowing close into a windward bank, so if the wind will allow it I will always attempt the more awkward short line casting into the wind with a shorter leader, possibly a mere 10ft with a brass beaded Hares Ear or buzzer on the point and a single buzzer on a dropper 4ft from the point. Trout will happily feed in 2 ft of water if food is there and it's not too bright. The same can apply when they switch onto shrimp or corixa on the lee shore anytime from June right through to November. It is very often quite difficult to see trout feeding in shallow water on these food items under a rippled surface, but I always assume and hope they are present . Both shrimp and corixa relish fairly shallow water, therefore on any overcast day especially from august through to November I would expect to find trout in the margins, so I look to have either a side wind or one blowing onto my back.
One thing is certain the wading angler is not likely to capitalise on these trout as wading will certainly drive them out from their chosen feeding area. Whereas the seated fly fisher keeping a low profile can enjoy fantastic sport without disruption. Shortline washing line tactics fishing a team of suspended nymphs kept floating by a buoyant point fly, can provide fabulous results. The weedbeeds I mentioned earlier will provide the perfect cover for perch and roach fry and as the beds slowly die back in the cooling water of late season, the better trout will cruise the edges, picking off the fry, so target fishing with floating fry patterns is both exciting and effective.
In my opinion there is no such thing as a blank day , for even if our net stays dry all day , usually somebody managed to catch, or we can learn from something or somebody. Most fly fishers are very happy to share how they managed to catch their trout. It is safe to say that the only thing we can't learn by observing a successful angler is merely the "magic" fly/Flies that caught the fish. Most of the details of an angler’s success can be observed without the necessity of conversation; we can see where he caught from. Was he wading, standing well back or seated? How many false casts and the distance cast? Was there a plop in front of the leader,(weighted point fly)? Length of time left before starting retrieve ?( how deep were his flies fishing)? Rate of retrieve or fished static( possible dry fly)? Continuous fig.of 8 or drawn. Fast or slow or even roly- poly? Does the rod tip drag down as the rod is raised ready to re-cast( fast sinking line)? So much information from a casual glance.
For the boat angler; Is the boat anchored or drifting with or without a drogue, running down the wind(rudder) side casting? As the line is retrieved does the rod tip drag down? ( heavy sinking line) Does the angler hang his flies before lifting off? Is the angler just keeping up with what looks like a floating line, (could be fishing dries or nymphs)? especially if a fair time before re- casting? Excessive deliberate false casting suggests drying a dry fly? Static boats around turbulent water holding off the boils? Obviously, we can see bent rods wherever success is happening, and seeing a bass bag hanging from gunwales is a good indication. When a bank angler is deliberately keeping a low profile on the bank, staying out of the water, has a bass bag laying keeping his catch cool, it is with good reason. It is obvious that fish are feeding close in the margins as the proof is visible. But so many other anglers will miss all the signs and proceed to wade directly into the water, standing exactly where their flies should be.
So, having observed so much for ourselves, plus whatever natural flies we see about, gives us a good insight into Reservoir success. Most fly anglers are quite happy to share details of any success, so a polite enquiry usually results in the last piece of the jig-saw being added, the magic fly or technique that made all the difference, to be tried out or stored away for a similar occasion to arise another day, or maybe next season.
Never be afraid to fish the big reservoirs, treat each area as you would a smaller water, you will soon gain confidence. Stick to just one to begin with, learn its topography and seasonal changes, build a relationship with knowledgeable friendly wardens and fellow anglers, this will all build confidence and ability to fish any reservoir.
Best wishes Ian.