Testing water quality of a river has changed in recent times from being an exercise in measuring for this and that to considering what makes the river water tick.
There are many ways to test a river. There is Physico-chemical Quality, which is Acidity (pH), Turbidity (clarity), temperature, presence of chemicals and so on.
There is Biochemical Quality BOD5 (biochemical oxygen demand) a measure of how the organic loading in water can consume its dissolved oxygen over five days.
And then there is Ecological Water Quality. What is in the river against what you would expect to find there. Basically, are the Wiggly's there? The little larvae and bugs that keep the rivers inhabitants well fed. The real sign of a healthy river.
At first sight, the River Teifi looks clean. Clear waters ease past grassy banks, woodlands and marshes towards Cardigan Bay. Sure, its chemical and biochemical quality is excellent, the right clarity, temperature, nutrient loadings and so on. Yet its wildlife is not quite what it could be. While Sewin (the local Sea Trout) and Salmon numbers are alright, Brown Trout numbers are not. There are a lot of invisible factors at play.
In the upper parts of the river, we are still suffering from acid rain a decade after this leached away from the lowland. The acidic soil cannot buffer the residual airborne pollution and forestry practices which encouraged swift drainage, and means that surface run-off is a real problem. The water is clear, but it does not harbour the insects whose larvae the fish need if they are to thrive.
Lower down, illegal sheep dip emptied into the river can wipe out insects and fish at any point for up to a mile downstream.
Who is to blame when supermarkets force farmers to sell their products at less than cost price? How can they afford the more expensive sheep dip (and the less harmful one) when they are finding it hard to put food on their own table? The percentage of what you pay for lamb going to the farmer has fallen by 25% since 1988, the rest going to the supermarkets.
Closer to the sea, it is the threat of over-abstraction and low flows during summer as new demands stretch an old resource.
What can we do? Well, upland management needs to take into account the value of a healthy river. We can buy from local organic farmers and growers that will mean less toxic run off for us and higher prices for them.
Water consumption can also be driven down with efficient equipment like dual flush loos and a better metering mentality.
But perhaps the single biggest hope for change is The Europe's Water Framework Directive. This law calls for allinland and coastal waters to have 'good ecological quality' by 2015. This means the wildlife that ought to be in each stream, river and rock pool should be there.
So in time a clean river will become a healthy one once more. The Brown Trout is looking forward to it.
by David Lloyd Owen
Tescopoly - a site dedicated to supermarket excess
The European Union Environmental Directorate General - studies and information on water policy
The Environment Agency