The body responsible for the Welsh environment has been condemned as a "disaster" for conservation as it marks its first anniversary.
Leading naturalist Iolo Williams also claimed Natural Resources Wales (NRW) was too close to the Welsh government.
And he accused it of a performing a U-turn by supporting plans for a motor racing track near Ebbw Vale.
The NRW said it was "really important" to protect the environment but also to develop and use it where appropriate.
The Countryside Council for Wales, Forestry Commission and Environment Agency Wales merged a year ago to form NRW.
Mr Williams said: "In its first year, Natural Resources Wales has been an absolute disaster when it comes to conservation.
"There are numerous examples of incidents of pollution in our rivers which haven't been looked into.
"There are incidents where they've done complete U-turns as well, not just with the race track in Blaenau Gwent but they did promise to tackle pollution in Llyn Padarn where you've got the very rare Arctic charr - nothing's being done there much to the disgust of local fishermen."
Mr Williams continued: "The problem goes very deep - I think you've got the upper echelon of staff there who are nothing more than civil servants, you've got the board who are nothing more than 'yes' men.
"All in all, over the first 12 months this new body has been an absolute disaster, and for the first time ever I am genuinely concerned for Welsh wildlife and the Welsh countryside."
He also criticised the NRW's independence.
But NRW chief executive Emyr Roberts disputed the catalogue of failures outlined by Mr Williams and defended its commitment to environmental protection.
He said: "Conservation is very much part of the role of Natural Resources Wales in managing the environment and it's really important that we protect but we also develop and use the environment where it's appropriate.
"It's a mixture of all those things and we need to get the best possible solution for the environment."
A spokesman for NRW added: "We investigate all pollution on rivers which are reported to us - if we were presented with any evidence to the contrary, we would investigate thoroughly."
He said steps had been taken to improve the habitat of the rare Arctic charr and a breeding programme was in place.
The spokesman added: "One of the benefits of Natural Resources Wales is that it will save the taxpayer in Wales over £127m over 10 years. It will also save time and money for people and businesses who will now have a single point of contact rather than three."
Calls have been made for the mission of the NRW to be clarified by the Welsh government.