New Zealand is losing 200 million tonnes of soil every year and polluting what remains with too much phosphorous.
Fish & Game chief executive Martin Taylor said it was "sobering and a wake-up call" following the release of Our Land Report 2018 that says New Zealand is damaging and losing its soils.
Martin said he thought the Government was focused on the report that showed wetlands, forests and waterways were coming under increasing pressure from unsustainable development.
The report identifies intensive agriculture as a major contributor to this damage and it revealed the staggering scale of the sedimentation problem.
"New Zealand is a small country but the report indicates that it is responsible for nearly 2 per cent of the world's sediment loss.
The report states that "overall, New Zealand contributes about 1.7 per cent of global sediment loss, while making up only 0.2 per cent of the global land area".
"The huge volume of soil being swept off our paddocks and hills is a serious problem and a real threat to aquatic life," he says.
"Soil is washing into our rivers, lakes, streams and harbours, where the sediment is smothering life and encouraging the growth of toxic algae.
"The sediment is choking fish and insect life in our rivers, destroying their habitat and hurting water quality. As worrying as the report is, it doesn't reveal the full story.
"It warns there are gaps in the available data and as a result, significant gaps in our knowledge, which means the problem may be far worse than it is saying.
"We need to urgently tackle these problems, including major changes to the way we manage and use our land to protect both our environment and economy."
Martin pointed to regional councils which were not doing their job properly, and had allowed this to happen.
"Cropping and "spray and pray" on hill country would be a good place to start to ban lazy and destructive farming practices which accelerates erosion and dirties our rivers," Martin said. "Regional councils are there to enforce existing laws and they have to lift their game.
"The current practice of overwintering stock also needs tighter control. Packing animals into small paddocks to eat crops to the bare ground is producing expanses of mud which wash into streams and rivers, smothering aquatic life with sediment.
"We have to do better, for the sake of our environmental and economic well-being. After a decade of neglect, we need proper protection of our resources, forest and rivers."
Our Land Report 2018 was jointly prepared by the Ministry for the Environment and Statistics New Zealand.
Fish & Game is a statutory public entity, established under the Conservation Act, to manage, maintain and enhance sports fish and gamebirds, and their habitats.
It is an organisation with specific responsibilities, including the conservation, Resource Management, walking access, Public Finance and Overseas Investment Acts.