A coloured Dorset Stour in summer (click for bigger picture)
A QUESTION OF COLOUR
A succession of fishing trips over the Christmas holiday period brought home to me how much the actual colour of the water affects our sport, on both rivers and stillwaters. Even the most pellucid waters of Dorset and Hampshire colour up at times, and most of the waters that I fish have some degree of colour during the winter. So, what causes that colour? And what is its effect?
Floodwater on Rivers
On the majority of rivers, the principal cause of the river colouring up is silt in suspension caused by rain, in other words floodwater. How bad this is depends partly on the time of year, partly on how the rain comes down and partly on the prevailing conditions. A good example is the very short, torrential downpour that we had on the night of the 27th December. In Dorset, we had about an inch of rain in ten minutes. The rain was so intense that it actually washed away a huge quantity of soil, and so, although there was not a massive flood, only about four feet up, the colour of the river was probably as dirty as it has ever been. In the days following, the river steadily dropped, and the colour diminished until five days later the river became what is locally known as green/brown, which is perfect for roach. And boy, did they feed.
Yet I have seen much higher floods where there is sustained flooding over several weeks with levels so high that the river is several fields wide for much at the time that eventually run clear as a greenish tinge. The nearby Hampshire Avon, much more dependant on groundwater, can actually run gin clear in these circumstances. It’s as if there comes a point when all of the loose sediment has been washed away that there is simply no more left to colour the river.
In wetter winters than the one we are currently experiencing, the chalk streams that enter the Stour between Blandford and Wimborne (the Allen, Tarrant and Winterbourne) run at a high constant level feeding in very clear water. As a result the Stour from Wimborne down runs fairly clear, yet venture upstream of Blandford and there is much more colour in the river. Conditions like this can make it hard to catch much at all downstream from Wimborne. The chub mind such conditions least of all but can get very wary.
A rising river isn’t always a curse
By far the best time for big roach is that small window of opportunity when the river is settling down after a big flood. On a big river this period can last for two or three days, whereas on a small river it might only last a matter of hours. During that short time, there is a better chance of not only a good bag but also the possibility that one of the big old wise roach will make a mistake. A prolonged flood that lasts weeks can really make the big ones hungry as well!
Mostly a rising river spells gloom for me as a roach angler. Barbel anglers might disagree, but trying to catch roach in a rapidly rising river is usually hard work. Sure, I might get a handful of roach in the first hour but the swim usually dies quickly. A colleague has mentioned that a couple of times this winter he has caught very big bream on the Stour on bread when the river has been just starting to colour up (the best was 9-14, a tremendous river fish).
A fairly clear Dorset Stour in winter (click for bigger picture)
Once in a blue moon a drop of rain can prove beneficial. Two occasions come to mind, one was a decade ago in a winter league on the Bristol Avon near Chippenham, the other this year in early January.
In the case of the winter league it had rained heavily from about 6 am until 8 am, not enough for a full-blown flood, but enough to put some colour into the nearby River Marden that entered the main river at the top of the match length. When I got to my peg at about 9 am the river appeared to be colouring up badly because of the sudden influx of coloured water from the Marden. After tackling up I walked down to my mate who had drawn a peg in the next section. Due to the nature of the venue this was nearly half a mile downstream. As I got closer to his peg I realised that the effect of the coloured water had not yet reached him. After chatting to him for 20 minutes it was time to return to my peg for the start of the match. By then the river had coloured up at his peg as well, but as I walked back upstream it became clear that the river was already settling down and by the time I got back to my peg the river was in perfect condition with just the right tinge of colour. Without that rain it would have been too clear. In the event it fished extremely well and I ended up with a cracking bag of roach on a stick float including fish to a pound and a half.
The other time was the day after the terrible storms that battered Northern England and Wales, flooding Carlisle, and causing widespread damage in early January. In Dorset we had the strong winds, with power lines brought down but the rain was less substantial that might have been expected with only about a quarter of an inch. When I got to the upper Stour I found it at normal winter level and a little on the clear side. The little brook that enters the river at this point was running about four inches up and coloured. When the brook is two foot up and very coloured then I worry. I sensed that the river might rise a little but there was unlikely to be a big flood on its way. So it proved. I fished for four hours and the river rose by about an inch an hour, very slightly colouring up as it did so. Far from getting harder, the roach fishing got better as the day wore on despite the strong winds.
On stillwaters it can be more complicated. Some stillwaters are fed by streams that can colour up the water. Others colour up as result of fish activity. Modern shallow commercial carp fisheries demonstrate this effect best of all. A succession of sharp frosts lowers the water temperature to the point where the carp, tench and bream are largely inactive. In alkaline waters the silt particles are coated with crystallized chalk salts and drop out of suspension. The water clarity increases dramatically and the fishing becomes difficult. This was the situation when Ron Clay, Peter Jacobs and I visited Wiltshire fishery Witherington Farm just after Christmas. There had been a succession of frosts, the carp had mostly stopped feeding and the water is chalk stream fed. As a result, the sediment dropped out of the water, and it was very clear and few carp were feeding (except in my swim!). I’m sure that if we’d returned three or four days later when there had been a consistent spell of much milder weather that the colour would have returned to the lake.
When milder weather returns in the spring it should be noticeable that the colour on this and other larger stillwaters will gradually increase. To a degree, this will be caused by the return of suspended algae, but mostly through the action of bottom feeding fish like carp and bream.
Whatever waters you fish, and regardless of species, getting to know the waters you fish and the effects of colour in the water is a vital ingredient to success. As your understanding increases it becomes easier to read other waters and adapt your tactics accordingly. Certainly, much clearer water has an effect on my tactics as a roach angler, whether it be what bait to use, or what size line and hooks, as well as how to approach the water, and even what species to target.
As a postscript, the onset of cold weather this week was enough to change the colour the Stour was carrying between Sunday the 20th February and Monday 21st. In just 24 hours it changed from 18 inches visibility to three feet.
Next: ‘It Looks easy but… what happened when I took a river novice fishing’