A river turned upside-down

River Bain with Senerwater above.

Every river angler knows that if you go downstream you will get to the sea eventually, and if you go upstream the river gets smaller and smaller. Up in the hills the water is full of oxygen and there are more stones than weeds so this is the place to look for bullheads, loaches and hopefully trout. Moving on down you might catch grayling, then more and more coarse fish and less trout until you reach the low, flat flood-plain where there might, or might not be, roach but there will be bream, perch, pike and carp.

It's unusual to find a river where this model does not apply, but then North Yorkshire's River Bain is no ordinary river. Officially the shortest in England, only 2 1/2 miles long, it flows out of Semerwater and then ambles along for about a mile doing nothing much before tumbling steeply through a wooded gorge in a rocky series of rapids and water-falls, with hardly any fishable pools all the way to Bainbridge. At the bottom of this half mile chute the water is going so fast that the villagers have installed England's first community hydro-electric scheme. It's really interesting: You should look it up.

By now you are probably ahead of me, or checking out the Bainbridge hydro scheme on the web, or asleep. But; You at the back! that's right; the coarse fish are all at the top of the river and the oxygen-hungry trout and grayling are at the bottom. It's an upside-down river. How can this be?

The last glaciation, about 10,000 years ago, was a mild affair compared to some of the earlier freeze-ups. The coarse grain of the Dales' landscape was created by the previous great sheets of ice that obliterated hills and valleys, but this last push was about creative landscaping; making lakes and pushing piles of soil around on a relatively moderate scale.

Semerwater looks like a classic hill tarn, carved out by a great lump of ice that stopped there and melted. It created a plateau of  fine, moraine soil in front of itself and dropped some really spectacular boulders with striations or scratches on them, showing that they were carried by glaciers. The French call these stones Roches Moutonnees, sheep rocks, but these rocks are as big as cows so I prefer to call them 'erratics' because they are plainly not from anywhere round here.

The river speeds up as it descends to Bainbridge.

The River Bain drains from the nose of the lake through this soft, glacial tilth in a meandering way, looking like a stream you might find in the Home Counties. Rich pastures are grazed by fat cattle and it all looks so normal. However, if you look around the rest of the Dales at this altitude you find poor, rough pasture of tussocks and rushes or peat moors with heather. That last glacier certainly did the local farmers at Stalling Busk a favour.

Semerwater is a strange place; full of legends. If you think of similar locations in Scotland or North Wales you realise that most glacail tarns are impoverished places, just big dents in the side of the rocky hills, filled with clear water. They have no fish, or they feature some lost char or whitefish trapped there since the Ice-age; no nutrients and probably no vegetation. Quite a lot of the water used in making Scotch Whisky comes from places like these, but this lake is more like a mere because it's on limestone and has nutrients. It harbours plants and fish; lots of coarse fish, and these have colonised the upper part of the Bain. But if they venture downstream, they die. There's no sign of coarse fish down in the River Ure below.

It's not a totally unique situation. In the Brecon Beacons, Llangorse Lake was formed in a similar way and is home to some great pike and coarse fish, while the River Usk below contains mostly trout and salmon. Several of the Cumbrian Lakes are similar. So, if you want to go coarse fishing in some smashing, upland scenery, you now know where to go. If you want to see a glaciated landscape that you can read like a book, let me recommend Wensleydale. It's perfect, glaciated scenery overlaid with human land-use that hasn't changed a lot since the Normans. It looks more French than anything ....and there's a splendid cheese that they don't have in France.

We are trout anglers at heart, but next time the river is in flood, or dried out, then my brother and I will be off to have a dangle in Semerwater.