An Olive Spring in the Usk valley |
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An Olive Spring in the Usk valley

Category: Fly Fishing Destinations | Author: Robert MacDougall-Davis

Robert MacDougall-Davis goes for a spring foray on the River Usk.

Mid April is a time of transition. It is the time of the season when fishing expeditions, previously inspired by hope, become fishing expeditions radiating with the strong sense of rod-flexing anticipation. Combine this with a yearning to brush off the last winter cobwebs and you can see what drives me on my annual spring pilgrimage to the magical Usk valley.

Spring fishing on the River Usk is a delight. Tree clad banks and great slabs of red sandstone provide a passageway for the amber water of the Usk as it cascades down from the limestone ridges of the Black Mountains before surging into Usk valley. On the upper river, clear glides pour into deep mysterious pools and moss quilted rocks carpet the exposed bed rock. Pale yellow primroses punctuate the moss-laden river borders with ever increasing frequency as spring permeates even the darkest corners of the valley.

The Usk catchment provides what is considered by many to be one of the finest freestone trout fisheries in the British Isles. The river is rightly renowned for harbouring a bounty of magnificent, fin perfect, leopard-spotted wild brown trout, each of which carry an idiosyncratic blue sheen brushed across their cheeks. As well as being home to an impressive trout population, the river Usk provides the stage for one of the most reliable and impressive Large Dark Olive (Baetis rhodani) hatches in Britain: a mouth watering combination!

Although Large Dark Olives (LDOs) trickle off the water from February through to November, the most substantial hatches are generally seen from late March through until the end of April when, triggered by rising water temperatures, the little up-winged insects can appear in droves. They also make a fleeting re-appearance in the late autumn but these hatches are rarely anything to rival those of the spring and seem to go relatively unnoticed by the local trout.


When fishing the LDO hatch I tend to reach for my trusty fast actioned 8’6 4wt. This is a rod that has enough backbone to punch small flies across or into the wind while also providing the finesse required to present a small dun to an Olive bashing trout. You could get away with using a 3wt but you’ll kick yourself for being under-gunned when, in fast water, you connect with one of the big, powerful and immaculately speckled Usk trout.

Although sizeable trout are not uncommon, it really pays to fish fine, especially when attempting to gently deliver small flies to selective trout. I believe it is better to have hooked and lost than to have never hooked at all! You will generally find me fishing a 9ft 0.152mm (5X) tapered leader with a 6ft tippet of either, 0.102mm (7X) 0.127mm (6X) or 0.152mm (5X) co-polymer. When using the lighter tippets (7X and 6X) I tend to put a small section of Rio Powergum into the leader as it offers a little more tippet protection for the strike and fight – a life saver when into a hard taking and head shaking 2lb beauty. It is really useful to carry a range of diameters with you as sometimes a prudent trout can be fooled by a swift reduction in the diameter of the tippet. As far as leader length goes the longer the better providing you do not overly compromise your ability to achieve good turn over and accurate presentation.


Timing is of the essence when Olive fishing on the Usk. LDOs are notoriously sensitive to climatic variations making it difficult to predict their exact emergence time. Generally, the hatch kicks off shortly after 11.00am, peaking around 1.30pm before coming to an abrupt end as a chill sets in about 4ish. To make the most of this window of opportunity lunch has to be put on the back burner or in my case hastily snaffled up while searching for the next spotted leopard.

A critical component of successful Olive fishing is to be highly tuned in to exactly what is going on above and below the water. Being aware of the various stages of Baetis rhodani is paramount as each individual stage will become a trout target as the hatch progresses. Like other members of the Ephemoptera order (mayflies) the life cycle of Baetis rhodani consists of; 1) egg, 2) agile darter nymph (various instars), 3) emerging nymph, 4) sexually immature dun (sub-imago) and 5) mature dun (imago). The astute fly fisherman will keep track of the hatch as it unfolds and the corresponding trout activity, changing tactics accordingly. Hawk-like observation, rapid changes of tactics, adaptability and quick thinking provide the key to successful spring Olive fishing.


As soon as flotillas of LDO duns start to sail downstream it is time to start scanning the water for any signs of activity in the plethora of gutters, runs and riffles, so characteristic of the upper river. Look for a nice lengthy run or pool below a long bumpy riffle. Remember, riffles are the nymph factory of any freestone river due, in part, to the increased oxygen concentration and the stable structure of the river bed which provides an excellent habitat for nymphs. When searching for productive water, try to avoid the runs and pools directly below waterfalls because the plunging water swallows up any adult duns drifting downstream reducing the density of flies perched enticingly on the surface.

When fishing the LDO hatch my fly selection consists of the magnificent seven, each pattern having its own unique catching ability. As far as nymphs go, I like to keep things simple, so I plum for a trusty size 18 weighted Pheasant Tail Nymph which can be prolific. The 'Steve McQueen’ of my dun imitations has to be the Olive CdC dun which is a superbly effective creation. If I find a rising fish that refuses to take one pattern, I’ll flash my other ‘go to’ patterns (Olive CdC emerger, Olive CdC dun, La Mirage, Duck’s Humpy, CdC Loopwing) past the trout - a tactic that usually results in a hit.

Most trout will be stationed throughout the hatch taking a combination of duns from the surface and nymphs below. With this in mind it really does increase your chances if you fish with two flies to imitate two different stages of the hatch at any one time.

During the early phase of the hatch and prior to fish latching onto the adult duns, I like to cover two bases by fishing a small (size 18) weighted Pheasant Tail trailing 3 ½ foot behind (NZ style) an olive CdC emerger (size 14-16). The emerger serves partly as an indicator as it dangles its undercarriage tantalisingly in the surface film and partly as a hoist which suspends the weighted PT in the nymph bashing zone. Hedging your bets like this also ensures that you’ll be ready for the moment when the trout switch their attention from hammering sub-surface nymphs to sipping emerging flies trapped in the surface film, as they struggle out of their cases in a bid to get airborne.

If you notice a procession of duns drifting along but no fish showing, the chances are that the trout are targeting the nymphs as they drift and rise off the river bed on their ascent to the surface. Keep your eyes peeled for the slightest bulge or boil in the surface film which often gives away the whereabouts of a hungry trout as it swipes a nymph from just below the surface film. For such fish the induced take can prove irresistible. Just as your nymph drifts onto the fish lift the rod tip and steadily hoist the small PT up through the water column. Hold your breath because the chances are that the PT will get nailed!

As time wears on and the hatch moves into full swing the PT will be sacrificed for an olive CdC dun, unless there is a headwind in which case I leave the PT on the tail as it greatly assists turnover when there is a brisk breeze.

Interestingly, I have found that trout are less likely to be interested in duns when hoovering up nymphs, but quite happy taking nymphs when predominantly feeding on duns. This is probably because a nymph has less chance of escape than a dun which can, at any moment, lift off the water surface and out reach of all but the most acrobatic of trout.

Once the first trout start to confidently break the surface, engulfing emergers and duns, the fun really starts. At this point in proceedings and through the peak of the hatch, I like to fish a dun and an emerger pattern in tandem (NZ technique). The fishing at this time can be frenetic as trout sip, suck and porpoise in their olive frenzy. If there is a momentary lull in activity scour the water with eagle-eyes for any surface disturbance such as dimples, noses piercing the water or anything that looks out of sync with the natural movement of the water surface.

It is amazingly easy to miss a rise right under your rod tip especially in ruffled water where even blinking can cost you that precious fish. Fish with a friend by your side and you will quickly realise just how many rising fish go unnoticed, so fish slowly and keep an eye on the water. What's more, bear in mind that big trout are often responsible for the tiniest rise formations or disturbance in the water, so when that little nose pops up and engulfs your fly be prepared for a whopper!

Wind, typical of early season expeditions, can be a great advocate when olive fishing. It greatly assists in disguising not only your leader and your general whereabouts, but also the fact that your fly is actually a ball of fluff and feathers and not a juicy LDO. Wind also makes things tricky for the emerging duns who are held captive in the surface film as they are buffeted from above. Olive wings act like sails and cause the newly emerged duns to skid across the surface which the trout, sensing the flies’ vulnerability, find irresistible. Scittering one of Agustino Roncallo’s feather light Mirages or Duck’s Humpies, to imitate a windswept dun can unlock a stalemate with a finicky trout and put an arch back in the rod. Windy, damp conditions can also increase the number of flies that fail to take off so fishing a cripple imitation in the sub-film can be very effective towards the end of the hatch.

If you encounter a shrewd trout that is up and down like a yo-yo as it gobbles up duns, but won’t touch your offering, then check you leader for kinks or blemishes and degrease your tippet before having another pop. Orvis mud or fullers earth mixed with washing up liquid does the trick nicely. A perfectly presented leader will often steal a march on a trout whose ability to correctly identify insects has been honed over more than 10,000 years of evolution.

Another trick for that canny sporadically rising trout is to repeatedly pass you flies over his head. This artificially enhances the density of the hatch, from the fish’s perspective, and has the power to bring up an otherwise indifferent fish. Concentrate, too, on the timing of your delivery. Trout tend to rise in varying rhythms. Rise, rise, rise, pause…….. rise, rise, pause…. and so on. Once you have seen your target rise, try to identify any obvious rising rhythm. There he goes again. Now relax and let him digest the positive feedback from the last mouthful, count to five, and only then plant your flies on the fish’s food conveyor belt. The secret is to insert your fly neatly into the trout’s feeding pattern and then hope for the best!

It is also worth showing the fish your fly on both sides of a trout’s position. During a recent sight fishing exploration in New Zealand it was apparent that fish can be left or right finned. They will often show a strong preference for a fly on one side of them and not the other, irrespective of current. Remember, the best position to cast to a rising trout is from behind the fish and at a slight angle so as to minimise drag and avoid lining the trout with your leader. To reduce drag as much as possible and to enhance presentation try not to cast across the flow to a fish unless wading and stalking up behind it is impossible.

As the LDO hatch peters out, a spent spinner imitation can be just the ticket. Spinners frequently get trapped beneath the surface as they float up exhausted from their egg-laying exploits. Fish will subtly sip away, as they pick off these drifting spents; it appears as though they are rising for ghost flies! If you are lucky, this can sometimes extend window of olive opportunity through until around 5pm. As a cloak of cool air descends on the valley I usually hightail it to the local inn for a pint of Milkwood, hearty meal and a crackling fire, rather than fishing out the dregs and soldiering on through the cold.

Accessing the magical upper Usk

The high quality and easy access of the Usk fishing owes much to the endeavours of the Wye and Usk Foundation. I take my hat of to them for all their sterling work and supreme friendliness. Their passport scheme, known by many as ‘the passport to paradise’, offers a wide range of upper Usk beats each of which have their charm.

Although the majority of the catchment provides excellent trout fishing, it is the upper Usk that is particularly enchanting. The upper beats not only provide superb fishing but also a sense of tranquillity that eludes so many of us in our day to day lives. To see the beauty of the Usk yourself visit my website at

Beech trees line the banks, standing like sentinels of the Usk, stretching their tendrils low over the river fringes and lanes of bubbles sidling their way along the surface. Spirited birdsong fills the air, as blackbirds, robins and thrushes sing with a passion and rapture that resonates all around. If you pass along the river quietly you might see a dipper skimming past, a bobbing wagtail or a bolt of blue as the king fisher whizzes by. If you are really lucky you might even glimpse an otter forging its way across the flow.

So if you are wondering how to satisfy your springtime urge to be on the water then why not visit the Usk valley to see the olive spring for yourself?

Useful Information

To see more Usk photography and other articles I have written visit my website:

Day Tickets (£15-£20) for all Wye and Usk foundation beats can be booked online: (EA bylaws apply).  The excellent Wye and Usk Foundation are always more than happy to offer tips and advice.

Fishing reports and a 24 hour web cam of the mid-Usk river gauge can be found online:

('This is the unabridged version of an article originally published in Trout and Salmon')

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