Last year, Natural Resources Wales (NRW) said it anticipated widespread failure of its protected rivers due to high levels of phosphates and it would likely advise that all new development within the failing catchment areas should be made phosphate neutral.
In January this year, the regulator set new targets for phosphate pollution in Special Areas of Conservation (SACs) across the country after it found that more than 60% of protected rivers in Wales exceed phosphate pollution limits.
According to the BBC, across Ceredigion there are 45 applications at a standstill because of the new rules, including 47 dwellings and 22 other applications.
Phosphate is naturally occurring and is released slowly, at low levels, from natural sources, from natural bankside erosion for example. However, phosphates can also enter rivers from farms, sewerage and foul water that can contain detergents and food waste.
Ceredigion MP Ben Lake told the BBC that something needs to be done to resolve the issue and clear the "log jam" that has built up since the start of the year.
The situation is especially acute in rural areas like Ceredigion which "are facing a housing crisis”, he said.
In a statement, the Welsh government said: "While we prioritise building affordable housing at pace in Wales, the resilience of our river ecosystems and the benefits they provide - including top quality drinking and bathing water to benefit our communities, our businesses and our wildlife - must not be jeopardised."