Water monitoring shows that the Isle of Man's rivers are among the cleanest in Britain, the Manx government says.
The government employs a marine biologist
The latest 2006 results from the Annual River Quality report produced by the government laboratory show that 98% were classed as fair or above average.
The government says that only a very small number of river are suffering "pollution stress".
A government freshwater biologist monitors more than 80 sites on the rivers for water quality.
Environment Minister John Shimmin MHK said: "Routine monitoring of water quality is the only way by which we can be alerted to the first signs of any deterioration in our rivers and so allow us to take action to prevent our rivers slowly slipping into an unsatisfactory state."