Eighty per cent of housing in the Shannon catchment relies on inadequate sewerage systems, according to an environmental alliance for the improvement of the Shannon water quality.
The alliance - a combination of the groups Save Our Lough Derg (SOLD) and Save Our Lough Ree (SOLR) - claims sewage from one-off houses and inadequate town treatment systems now represents one of the biggest threats to water quality in Ireland's longest river.
While it acknowledges that many towns along the waterway are improving their waste water plants with EU and State funding, it claims a major difference could still be made if people were aware of potential damage to the river from badly functioning septic tanks and treatment plants, as well as a range of activities, including industry, farming and boating.
The alliance has now drawn up a voluntary action programme, condensed into a series of small advisory brochures, which will be launched by the Minister for the Marine, Mr Fahey, and the Minister for Public Enterprise, Mrs O'Rourke, in Athlone next Monday.
The brochures cover advice for the farming community, boat owners, builders and others on how to ensure their activities do not impact adversely on the Shannon. At a cost of €13,000 they were funded by the Department of the Marine.
According to Mr Harry Waterstone, chairman of SOLR, there are 150,000 houses on septic tanks in the catchment area. "Many of these would be old-style septic tanks and we must encourage the Government to give grants towards their replacement by more pure, bio-based systems.
"New builders should and generally will conform to modern standards but many people in one-off housing don't know that putting thinners, pesticides, paints, solvents, disinfectants and cleaners into septic tanks generally has the same effect as putting them straight into a lake. They all end up in the same place."
According to Mr Waterstone, farmers could and should lobby for treatment plants for excess winter sludge, while boaters should ensure that all boats are fitted with holding tanks.
While most hire boats and all new private boats on the Shannon now have holding tanks fitted, Mr Waterstone points out that in many cases access to pump-out facilities is not easy. "If you ask a local authority does it have the facilities, it will probably say yes. But if you ask are they in use, you may get a different reply," he said.
Last July, a report of the catchment monitoring committee on the quality of water in the Shannon suggested that as much as 35 per cent of the waterway may be significantly polluted.
This figure was, however, a reduction of the order of 10 per cent on previous reports which had found the waterway to be more seriously polluted.
The report, drawn up by consultants Kirk McClure Morton for local authorities and the European Union, acknowledges significant improvements from local authorities in the installation of waste water treatment plants, but criticises the level of industrial pollution coming from plants in towns which are licensed by the local authorities.
The report singles out the Hind river, which flows into Lough Ree from Co Roscommon, as having one of the worst levels of pollution.
A website has also been set up with information on voluntary measures which can be taken to reduce environmental pollution. It is at www.shannonwaters.ie.