Yorkshire Water has defended its bid to relax controls on the treated sewage it discharges into the River Aire.

And the Bradford-based company has promised to hold a public meeting to discuss the application with concerned residents.

Conservationists and anglers yesterday met with Yorkshire Water's area manager Judy Anderson who told them the aquatic life in the river would not be harmed by the proposal.

As previously reported, Yorkshire Water has applied to the Environment Agency to relax restrictions on the amount of effluent, ammonia and suspended solids released into the river for a two-year period.

It has applied to the Environment Agency for a relaxation in order to carry out a cleaning programme on its 70 filter units at its Esholt treatment works.

The filters have become clogged up over the years - at a faster rate than was expected - and the company wants to flush them to clear away the sludge which has built up.

Yorkshire Water says it is impossible to isolate the flushed material from the flows already being discharged into the river. This means that as each of the 70 filters are flushed the company runs the risk of exceeding the allowed limits of effluent released into the river. Miss Anderson said: "This is really for us a precaution so we are able to remain within the legal constraints imposed by the Environment Agency.

"We don't anticipate we are likely to go over our current constraints.

"Our concern as a company is that we don't want to go into this and risk failing our current constraints because the consequences of that are so severe for us. If we are not able to do this work the deterioration we have already seen will continue."

If the company went above the accepted limit it risked prosecution.

Miss Anderson said 19 other options had been considered but flushing the filters was considered the most effective.

The company is asking to relax the levels of effluent from 10 milligrammes per litre to 12, of ammonia from five milligrammes per litre to seven, and suspended solids from 20 milligrammes per litre to 40.

And Councillor Martin Love (Green, Shipley West) said he would like to see the Environment Agency monitor the site on a daily basis if the work went ahead. It currently takes weekly readings.

He added he wanted conditions imposed so the flushing would stop if the river level dropped in times of drought.

Aire Valley Conservation Society secretary Penny Ward said she was disappointed more people had not been invited to the meeting and was pleased the company had agreed to extend its consultation.

"I can see that the work is necessary but I am concerned about what happens in a drought situation. There needs to be stringent conditions imposed to protect the river," she said.