Spate Part One.

Part one is for background. Part Two will be about the river from a trout's viewpoint and Part Three will be personal recollections of fishing in a spate using worms.

 

I learned in school that the North Pennine rivers that flow into the Yorkshire Ouse can be remembered by the mnemonic “SUNWAC”. These rivers are the Swale, Ure, Nidd, Wharfe, Aire and Calder and they all have tributaries that flow from the eastern side of the watershed. For exam purposes, the Vale of York was considered to be an area worthy of study but not Durham and Northumberland, so the Tyne, Wear and Tees had to be studied with a fishing rod later. The Ribble and the Lune systems flow down the west slope of the Pennines to Morecambe Bay.

The High Pennines are shrouded in cloud for most days of the year. You probably cannot see the tops but it is certainly raining there, and quite probably not where you are, which is perhaps only 5 miles away. Rain falling on rocks runs swiftly off, but the Pennine limestones are full of holes that can swallow a river, forcing it to travel for miles underground before it emerges in a new place.

A lot of the high ground is covered in peat moors that are mostly managed for grouse shooting. The spongy peat is already full of water so adding more rain on top just pushes more water out lower down. Run-off has been accelerated by digging “grips” or ditches that drain bogs to produce more heather for grouse. The hunched shoulders of the Pennine Hills shed water like an old oilskin coat.

On the default grey drizzly day with a roke-mist over the hills, the peat hags drip clear water to maintain springs lower down and give life to the Pennine becks. During a heavy storm the peat starts to wash away, staining the water to the colour of strong Yorkshire Tea with no milk. Little runnels form through the grassy high pastures and tumble into the hanging valleys, foaming over rocks and down through cascades and spectacular water falls. All of these features have their own names in the Dales dialect that has been handed down from Danish settlers; beck, ghyll, ing, foss or force. Now the water looks more like frothy Guinness and the level in the river may be up by a foot or so.

If heavy rain continues the river will burst it’s banks and start to pick up soil from the valley. Farm lanes turn to mud and muck that all ends up in the river which is now a boiling soup of thick brown water with trees and rubbish on top and rolling boulders beneath. There are no pools or rapids, just a parading river with standing waves that form above any submerged object like a car or a bridge. 

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Spate rivers fluctuate from flood to drought in a very short time at any time of the year, so they could equally be called “drought rivers”. They make for a challenging environment for any creature that lives in the water or on the bank. The flow can wash you and I away, it can even destroy stone bridges, so imagine what it does to fish and invertebrates. 

After a few weeks without rain the rivers “show their bones” and become a shrunken series of puddles between hot rocks. The still, shallow pools warm up to become a frothy soup. If a thunderstorm occurs on the tops, they can become a rolling, raging brown torrent within an hour. 

A Pennine stream might descend over 1000 feet in 20 miles through a series of white-water falls and rapids that suck in bubbles of air. In the process, the cold rushing water becomes extremely rich in life-giving oxygen. In periods of low flow the oxygen becomes depleted and, when the water heats up, it’s ability to hold oxygen declines. Mobile creatures may move out to better spots but many creatures, including some fish, will die. 

People have generally retreated from the banks unless they are mill owners, but riverside mills do not occur randomly; they stand in narrows on solid rock that will not move in a spate. 

Two generations of my family lived close to the hissing, rushing water of a Pennine beck and they recall the booming Armageddon sound of huge boulders on the move in the night. In a spate like that, the river may shift it’s course entirely, ripping it’s way behind bankside trees and walls. Even within the old course, pools may be filled with rocks or replaced with rapids and fallen trees may temporarily block the flow to create new pools. 

Floods like that normally occur in Autumn or Winter when wild brown trout spawn. The main river is  not a suitable habitat for eggs or fry, so the fish ascend the smallest tributaries to find more reliable gravel beds that are rich in oxygen while being fast-flowing enough to resist freezing. Trout run upstream and then divert up the smallest of ditches or gutters to mate and spawn in perhaps two inches of water. The fish, which are now black and almost unrecognisable, are exposed to predators like herons on the bank and otters in the water but the eggs need fine gravel beds in oxygen-rich water to survive. 

When you think about it, freshwater fish must lay their eggs upstream, otherwise all of our fish would become marine species. Indeed salmon and sea-trout migrate many miles up from the salt to lay their eggs, even though the adults will live in the ocean. In recent years these migratory fish have made a return to the Pennines. Sometimes the flat-rock beds of pools in the upper reaches of Pennine rivers will be littered with the bodies of brook lampreys that have migrated there to spawn and die. Eels also make it high up the rivers, but they must make their way back to the ocean to reproduce.

Fast flowing becks and burns play host to a spectacular variety of wildlife but they are much more vulnerable than they look. Excessive flood and drought cycles take their toll but worse things can happen. In the 19th Century the Pennine Dales were mined for lead, silver and coal. The valleys were deforested for fuel and the streams were diverted for power and for washing minerals. It was an industrial landscape and the pollution levels were extremely high. Bare hillsides (labeled as “poison ground” on maps) still exist where nothing will grow. Insect and fish life in some rivers must have been pretty much extinct, but they miraculously recovered.

Upland agriculture changed in the !960s with the introduction of sheep dip that was used in the sheep folds and allowed to run into the becks where it killed the insect life and young fish. Chemical fertilisers came next as farmers maximised the use of the riverside fields for hay and silage production. The rocky stream beds often became slippery and green with algae in summer. Abstraction for domestic water supplies made matters worse and some acidification was caused by planting dense stands of conifers in the catchments. 

Just now, the rivers are in a pretty good state as long as they still have water in them but new problems seem to arrive every year. Perhaps the biggest threat currently comes from invasive species of plants and animals that do not belong here.

(This story could be expanded to cover more of the wildlife such as crayfish, grouse, dippers, kingfishers etc.)