The River Irfon: clear-water Welsh queen

The Irfon (pronounced Eervon) glides over wide sections of smooth bedrock, seethes relentlessly in deep pools and barrels down gutter-like channels, giving the angler plenty of water to scratch his head and think about. You certainly won’t get bored fishing the Cammarch Hotel stretch.

From the sheer availability of river features, the Irfon may even seem daunting to the new angler. One place that’s worth investigating, according to Alan Tansley, proprietor of the Cammarch Hotel and regular Irfon fly fisher for thirty years, is the stretch around Nant Mill Pool which offers trout and grayling four distinct, yet characteristic types of habitat – the riffle, run, pool and glide.

Like those of most freestone rivers (where the flow depends on the amount of rainfall), the habitats or features of the Irfon can change dramatically, given a substantial amount of rain. For example, a riffle may look like a fast trickle from a hosepipe in low-water summer conditions but virtually disappear when the river is in spate, baffling the one-day visitor.

With two other rivers flowing into it (the

Dulais and the Cammarch), the Irfon’s level rises quickly and alarmingly. But because it flows over bedrock and has very few silty areas, it keeps its clear, colourless purity in all but torrential downpours when any river is prone to look like milky coffee.

Trying to define ‘normal conditions’ on a freestone river such as the Irfon is asking for controversy. But with the exception of heavy rains and melting snow, riffles and other features remain fairly identifiable.

The riffle

Well upstream of Nant Mill Pool the water is shallow (30-45cm/12-18in deep), fast flowing and turbulent at the surface.

Stones -just large enough to get in your way and trip you up – litter this riffle upstream of Nant Pool Mill. There are a few gravel areas here and there as well.

Most nymphs, especially the flat-bodied, stone-clinging ephemerids, prefer this habitat because the water is well-oxygenated, and there are countless nooks and crannies to hide from predators. Cased caddis larvae also abound, along with a few stonefly nymphs.

In the summer – especially during the day – trout prefer this type of fast water on the Irfon (and other small rivers) because of its oxygen content and because it breaks up any light which may penetrate the thick canopy of trees along the banks. Buoyant dry flies in size 14 (such as Elk Hair Caddis or Klinkhammer Special) tempt a fair share of trout from behind rocks and out from sheltered crevices in the bedrock.

During the evening and at night the trout may move out of the faster water into the slower-moving stretches in search of fry or hatching sedges.

In the colder months of the year the trout and grayling avoid riffles altogether – not wanting to waste valuable energy contending with the current for what little insect activity is present.

The run

Above Nant Mill Pool there is a run which contains deeper, slower-moving water (45-120cm/r/2-4ft deep) with a less turbulent surface; it follows the riffle. Runs usually contain the biggest fish in the warmer months – and especially here because of the ample shade. The fish don’t have to work as hard, swimming in the current, and the deeper water offers more security.

Whereas grayling are generally nomadic, shoaling fish, moving long distances up and down the river in search of suitable lies, brown trout are highly territorial. The biggest browns establish and defend the best areas which offer security, deep, oxygenated water and food.

Runs are primary lies for big trout during the day in the warmer months. At night the fish may move to the pools or slower reaches in search of sheltering fry. Smaller trout are relegated to division four — that is, forced into the slower moving sections where the food and oxygen content are less abundant. As a general rule, runs follow riffles and precede pools. The Irfon has many long U-shaped runs which you should seek out. Leaded nymphs or even dries may succeed in tempting these fish. You might want to try fishing a sombre-coloured lure (such as Whitlock’s Sculpin) downstream, hard along the bottom at the end of the riffle and beginning of the run.

Nant Mill Pool

Split in two near the centre by a small sunken island of rock, Nant Mill Pool is a well known salmon area. In the autumn many salmon take up residence here, lying hard along the bottom.

Along both banks the water flows through deep channels where there are many miniature cliffs of overhanging bedrock. A rod length or so from either bank puts you in the deep water (2-2.5m/7-8ft deep) – this means wading is impossible.

Fish Nant Mill Pool (and others on the Irfon) in autumn because the temperature-senstive grayling retreat to deep water. Browns may also be present until late June. Deep pools are the best early season venue. Fish them first, the deep runs second.

In July and August, however, you probably won’t find too many fish in the slow-moving pools – the faster water is better.

If you fish from the bank, the trout can see you if you’re not cautious. Creep down the steep, grassy bank, and with a heavy nymph (Klinkhammer’s Leadhead Nymph and goldheads are superb), fish across and down, the fly trundling over the bedrock and gravel river bed. Trout and grayling will be hard along the bottom – they don’t adopt mid-water lies in freestone rivers.

When the nymph swings around and is directly downstream of you, twitch it upstream past the overhanging willows and bushes. Many trout and grayling lie close to shore in the deep water. If the river is high, the flooded bushes and grass provide shelter for fry. Trout and even big grayling lie close by, waiting to ambush them, should they venture too far away from the security of their cover.

A smooth glide

Just downstream of Nant Mill Pool is a long stretch of water which flows at a moderate rate, has little surface turbulence, plenty of weed growth in the summer, a gravelly bottom and a depth of 60-120cm (2-4ft): it’s a superb stretch of water known as a glide.

If you want grayling in the summer and warmer autumn months, glides like this are the place to go. Streamer weeds with long fronds hide agile-darting (ephemerid) nymphs and large freshwater shrimps. In the clear water you can sometimes see dark shapes detach from the bottom, rise to the surface and gently sip in emerging small dark olives. Near the slower-flowing sections close to the banks of the glide are areas of silt – perfect for bloodworms and midge pupae. Towards evening, trout may seek bullheads hiding among the stones.

This is dry fly (or emerging nymph) territory — to be waded and fished upstream with long leaders and tippets no heavier than 2 lb (0.9kg). Duck’s Dun, Once and Away and the ever-reliable Adams in sizes 14-16 are suitable.

Emerging nymphs fished in the surface film also take a fair share of fish. It’s essential in slow water to use flies on the small side and to degrease your tippet regularly.