Brecon, Radnor and Cwm Tawe MP David Chadwick has said the discovery of dangerous bacteria at a River Wye bathing spot is “deeply disturbing”.
The Warren, a pebbled beach area on the river near Hay-on-Wye, is a popular site among wild swimmers and was granted official bathing status last month.
But swimmers were last week advised to stay away from site due to the discovery of E.coli and intestinal enterococci bacteria.
The levels of both bacteria found were five and seven times higher respectively than the lowest quality standard considered "sufficient".
The Welsh Lib Dems have labelled the news as “disgraceful” and have vowed to tackle water pollution in Wales.
The party has previously called for the replacement of Ofwatt with a more effective and harsher water regulator to ensure that water companies who are guilty of dumping raw and untreated sewage are being punished.
MP for Brecon, Radnor and Cwm Tawe David Chadwick said: “The discovery of dangerous bacteria at the Warren is deeply disturbing and highlights just how severe sewage pollution is in our waterways here in Wales.
“We cannot allow water companies to treat our beautiful natural environment as a dumping ground for untreated raw sewage.
“In the last election we campaigned on a promise to clean up our rivers and coastlines, and this is a promise we intend to keep.”
Leader of the Welsh Liberal Democrats Jane Dodds MS said she was “dismayed” to see the site is no longer suitable for use.
“It is disgraceful that this beautiful river has been left to get into such a state to begin with,” she said.
“For far too long now water companies have got away with polluting our beautiful rivers and coastlines without fear of punishment.
“During the recent general election, we as the Welsh Liberal Democrats vowed to clean up our waterways and punish those guilty of dumping sewage, this is a promise that we intend to keep.”
Cllr Gareth Ratcliffe (Hay) added: “The discovery of the bacteria should highlight just how desperate the situation is regarding sewage pollution in the river Wye and how much work needs to be done to ensure that the river is safe for use.
“We must do more to ensure that our waterways here in Wales are both clean and safe for everyone to enjoy.”