Industrial
pollution tends to be of minor consequence in highland
rivers,
but agricultural pollution can be a major problem.
Perhaps the most significant being sheep dip. There
are two forms
of dip organophosphate and pyrethroids (cypermethrin).
The former are dangerous to the handler and the later
lethal to aquatic life. Cypermethrin was
banned in 2006 (except that existing stocks could
still
be
used).
See the public
notice.
See the report by The Welsh Salmon & Trout Angling
Association Sheep
Dip - Update by Ceri Evans showing the impact on
fish.
Recent government
studies have shown that even if best practice
is observed sheep dip will escape the farm and that
a single sheep fording a burn will release sufficient
chemical to
seriously reduce salmon and trout reproduction for
300m.
Hopefully cypermethrin will continue to be banned.
Other forms of agricultural polltion include slurry
which will de-oxygenate very effectively.
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A midden right next to a burn flowing into the River
Lochay
And in that dump
- empty containers of sheep dip
and other animal treatments.
A salmon killed by a plastic ring.
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