Silt is not good for the aquatic environment, at least not in the quantities we see now.
Many insects that live on the riverbed do not thrive in a silty environment, as the silt fills in the spaces between the stones where they live, resulting in their decline, especially mayflies.
Some species of caddis also decline and stoneflies have almost completely disappeared from lowland streams.
Fish that spawn in gravel are also affected as they bury their eggs in the gravel. When silt is deposited on the riverbed, the eggs are smothered and die and fish numbers drop.
The fish also have less of their usual prey to feed on and have to expend more energy looking for alternative food.
One of the major causes of increased silt in rivers is land drainage, but this is being addressed by such groups as the Pomahaka Water Care Group, with riparian planting and silt traps.
Over time, as these actions begin to take effect, the silt should decrease.
However, the major cause of heavy silt load in recent years has been erosion, exacerbated by big floods which can move millions of tonnes of silt into a river course.
These floods are becoming more frequent as the climate warms. With no action from politicians, it is only likely to get worse.
Historically, mining has been a major source of silt entering rivers. With lots more mining ahead o generate "wealth", regardless of the environmental consequences, the future does not look bright.
In the short term there are still fish to catch, which takes our mind off the cares of the world, at least for a few hours.
My last efforts were on the lower Taieri on a nice sunny day, only marred by the vast quantity of silt stirring up as I waded up the river.
I fished a favourite ripple with a weighted nymph to no avail, only hooking logs embedded in the silt.
On the flatter water I saw the odd rise, but they were irregular and it was difficult to get a fly in front of them.
There was one fish, that I am sure saw my fly as it stopped rising as soon as I covered it. At one point, a fish rose several times in the same spot as I approached it. This could be the only fish of the day I thought, so the first cast must count.
I plonked my unweighted nymph close to the rings of the latest rise and gently lifted the rod and hooked the fish.
