The Advertising Standards Authority (ASA) has upheld a complaint of inaccuracy about a Greenpeace billboard claiming two large agriculture firms were causing river pollution.

The environmental group’s billboard said “Ravensdown and Balance Pollute Rivers”. Also included on the billboard was a Twitter hashtag, #TooManyCows.

The ASA received three complaints about the billboard stating it made a false claim. One complainant said it is the farmers who are polluting the rivers, not the fertiliser producers. Another said there wasn’t enough evidence to back up this claim, and the statement that there are too many cows is an opinion not a fact.

Greenpeace said the environmental impacts of synthetic nitrogen fertiliser are both direct and indirect. The direct impact occurs from the application of the fertiliser itself, the indirect impact occurs from the intensification of farming that is enabled by the application of synthetic nitrogen.

“Greenpeace believes that the advertisement serves the public interest by raising public awareness and generating discourse on water pollution, while offering a critique of the impacts of the powerful and influential New Zealand fertiliser and dairy industries,” it said in its response.

A majority of the ASA’s Complaints Board said the advertisement was misleading because the message was over-simplified and potentially unclear. A minority of the board said in the context of advocacy advertising Greenpeace had provided sufficient substantiation to support its view.

The complaints were upheld.