STRETCHES of the Colne, Calder and Holme rivers are to be dramatically cleaned up.
The move comes as part of new European Union legislation, the Freshwater Fisheries Directive.
But officials admit that the improvements will mean bigger water bills.
An Environment Agency spokesman said: "The Government's environmental priorities for water industry investment between 2005 to 2010 will deliver major improvements for communities and the environment."
Plans include improved sewage treatment by Yorkshire Water and prior treatment to sewage discharge in storms.
This will clean up unsightly and foul- smelling litter left on riverbanks.
The spokesman added: "These improvements will help restore the ecological balance of lakes and rivers.
"This will encourage the return of healthy fish populations and will mean more attractive conditions in and around the rivers, not only for anglers, but also for walkers, river users and local people."